Nicotine salt formulations for aerosol devices and methods thereof

Abstract

To provide a nicotine salt liquid formulation for generating an inhalable aerosol in an electronic cigarette comprising a nicotine salt that forms about 0.5% to about 20% nicotine.SOLUTION: A method of delivering nicotine to a user comprises operating an electronic cigarette for a user, where the electronic cigarette comprises a nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier, where an acid used to form the nicotine salt is characterized by vapor pressure greater than 20 mmHg at 200°C, and inhaling an aerosol generated from the nicotine salt formulation heated by the electronic cigarette.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] <Cross reference> This application claims the benefit of U.S. Provisional Patent Application No. 61 / 820,128, filed May 6, 2013, and U.S. Provisional Patent Application No. 61 / 912,507, filed December 5, 2013, which are incorporated herein by reference in their entireties. Summary of the Invention [Means for solving the problem]

[0002] Provided herein is a method of delivering nicotine to a user, the method comprising: having the user activate an electronic cigarette, the electronic cigarette containing a nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is characterized by a vapor pressure of greater than 20 mmHg at 200°C; and inhaling an aerosol generated from the nicotine salt formulation heated by the electronic cigarette.

[0003] Provided herein are methods of delivering nicotine to a user, the methods including the steps of: having the user activate an electronic cigarette, wherein the electronic cigarette contains a nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is characterized by a vapor pressure of 20 to 200 mmHg at 200°C; and inhaling an aerosol generated from the nicotine salt formulation heated by the electronic cigarette.

[0004] Provided herein are methods of delivering nicotine to a user, the methods including: activating an electronic cigarette, wherein the electronic cigarette contains a nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is further characterized by a melting point below 160°C, a boiling point above 160°C, and a difference between the melting point and the boiling point of at least 50 degrees; and inhaling an aerosol produced from the nicotine salt formulation heated by the electronic cigarette.

[0005] Provided herein are methods of delivering nicotine to a user, the methods including providing an electronic cigarette to the user, the electronic cigarette containing a nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein an acid used to form the nicotine salt is further characterized by a melting point at least 40 degrees below the operating temperature of the electronic cigarette, a boiling point no more than 40 degrees below the operating temperature of the electronic cigarette, and a difference between the melting point and the boiling point of at least 50 degrees, and inhaling an aerosol produced from the nicotine salt formulation heated by the electronic cigarette.

[0006] Provided herein is a method of delivering nicotine to a user's blood, the method comprising providing an aerosol to be inhaled by a user from an electronic cigarette comprising a nicotine salt formulation, the aerosol providing comprising the electronic cigarette heating the formulation, thereby generating the aerosol, the aerosol effective to deliver a nicotine level in the user's blood that is at least 5 ng / mL for about 1.5 minutes after the first of 10 puffs of the aerosol, each puff being spaced 30 seconds apart.

[0007] Provided herein is a nicotine salt liquid formulation in an electronic cigarette for producing an inhalable aerosol upon heating of the electronic cigarette, the formulation in the electronic cigarette comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is characterized by a vapor pressure of greater than 20 mmHg at 200°C.

[0008] Provided herein is a nicotine salt liquid formulation in an electronic cigarette for producing an inhalable aerosol upon heating of the electronic cigarette, the formulation in the electronic cigarette comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is characterized by a vapor pressure of about 20-200 mmHg at 200°C.

[0009] Provided herein is a nicotine salt liquid formulation in an electronic cigarette for producing an inhalable aerosol upon heating of the electronic cigarette, the formulation in the electronic cigarette comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is further characterized by a melting point below 160°C, a boiling point above 160°C, and a difference of at least 50 degrees between the melting point and the boiling point.

[0010] Provided herein is a nicotine salt liquid formulation in an electronic cigarette for producing an inhalable aerosol upon heating of the electronic cigarette, the formulation in the electronic cigarette comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is further characterized by a melting point at least 40 degrees below the operating temperature of the electronic cigarette, a boiling point no more than 40 degrees below the operating temperature of the electronic cigarette, and a difference of at least 50 degrees between the melting point and the boiling point.

[0011] Provided herein are nicotine salt liquid formulations for producing an inhalable aerosol upon heating in an electronic cigarette, the nicotine salt liquid formulations comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is characterized by a vapor pressure of greater than 20 mmHg at 200°C.

[0012] Provided herein are nicotine salt liquid formulations for generating an inhalable aerosol upon heating in an electronic cigarette, the nicotine salt liquid formulations comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is characterized by a vapor pressure of about 20-200 mmHg at 200°C.

[0013] Provided herein are nicotine salt liquid formulations for producing an inhalable aerosol upon heating in an electronic cigarette, the nicotine salt liquid formulations comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is further characterized by a melting point below 160°C, a boiling point above 160°C, and a difference of at least 50 degrees between the melting point and the boiling point.

[0014] Provided herein are nicotine salt liquid formulations for producing an inhalable aerosol upon heating in an electronic cigarette, the nicotine salt liquid formulations comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is further characterized by a melting point at least 40 degrees below the operating temperature of the electronic cigarette, a boiling point no more than 40 degrees below the operating temperature of the electronic cigarette, and a difference of at least 50 degrees between the melting point and the boiling point.

[0015] Provided herein are nicotine salt liquid formulations for use in electronic cigarettes, the nicotine salt liquid formulations comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is characterized by a vapor pressure of greater than 20 mmHg at 200°C.

[0016] Provided herein are nicotine salt liquid formulations for use in electronic cigarettes, the nicotine salt liquid formulations comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is characterized by a vapor pressure of about 20 to 200 mmHg at 200°C.

[0017] Provided herein are nicotine salt liquid formulations for use in electronic cigarettes, the nicotine salt liquid formulations comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is further characterized by a melting point below 160°C, a boiling point above 160°C, and a difference of at least 50 degrees between the melting point and the boiling point.

[0018] Provided herein are nicotine salt liquid formulations for use in electronic cigarettes, the nicotine salt liquid formulations comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is further characterized by a melting point at least 40 degrees below the operating temperature of the electronic cigarette, a boiling point no more than 40 degrees below the operating temperature of the electronic cigarette, and a difference between the melting point and the boiling point of at least 50 degrees.

[0019] Provided herein is the use of a nicotine salt formulation for delivering nicotine to a user from an electronic cigarette, the nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is characterized by a vapor pressure of greater than 20 mmHg at 200°C, and the nicotine salt formulation is heated by the electronic cigarette to produce an aerosol that is inhalable by the user.

[0020] Provided herein is the use of a nicotine salt formulation for delivering nicotine to a user from an electronic cigarette, the nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier, the acid used to form the nicotine salt being characterized by a vapor pressure of about 20 to 200 mmHg at 200°C, and the nicotine salt formulation being heated by the electronic cigarette to generate an aerosol inhalable by the user.

[0021] Provided herein is the use of a nicotine salt formulation for delivering nicotine to a user from an electronic cigarette, the nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is further characterized by a melting point below 160°C, a boiling point above 160°C, and a difference of at least 50 degrees between the melting point and the boiling point, and wherein the nicotine salt formulation is heated by the electronic cigarette to produce an aerosol that is inhalable by the user.

[0022] Provided herein is the use of a nicotine salt formulation for delivering nicotine to a user's blood from an electronic cigarette, wherein the nicotine salt formulation in the electronic cigarette is heated to form an aerosol, and the aerosol delivers a nicotine level in the user's blood of at least 5 ng / mL within about 1.5 minutes after the first of 10 puffs of the aerosol, each puff being spaced 30 seconds apart.

[0023] Provided herein is the use of a nicotine salt formulation for delivering nicotine to a user from an electronic cigarette, the nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is further characterized by a melting point at least 40 degrees below the operating temperature of the electronic cigarette, a boiling point that is no more than 40 degrees below the operating temperature of the electronic cigarette, and a difference of at least 50 degrees between the melting point and the boiling point, wherein the nicotine salt formulation is heated by the electronic cigarette to produce an aerosol that is inhalable by the user.

[0024] Provided herein is a cartomizer for an electronic cigarette, the cartomizer comprising: a nicotine salt liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is characterized by a vapor pressure of greater than 20 mmHg at 200°C; an atomizer including a heating element in fluid communication with the nicotine salt liquid formulation; and a fluid storage compartment for storing the nicotine salt liquid formulation.

[0025] Provided herein is a cartomizer for an electronic cigarette, the cartomizer comprising: a nicotine salt liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is characterized by a vapor pressure of about 20 to 200 mmHg at 200°C; an atomizer including a heating element in fluid communication with the nicotine salt liquid formulation; and a fluid storage compartment for storing the nicotine salt liquid formulation.

[0026] Provided herein is a cartomizer for an electronic cigarette, the cartomizer comprising: a nicotine salt liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is further characterized by a melting point below 160°C, a boiling point above 160°C, and a difference of at least 50 degrees between the melting point and the boiling point; an atomizer including a heating element in fluid communication with the nicotine salt liquid formulation; and a fluid storage compartment for storing the nicotine salt liquid formulation.

[0027] Provided herein is a cartomizer for an electronic cigarette, the cartomizer comprising: a nicotine salt liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is further characterized by a melting point at least 40 degrees below the operating temperature of the electronic cigarette, a boiling point that is no more than 40 degrees below the operating temperature of the electronic cigarette, and a difference of at least 50 degrees between the melting point and the boiling point; an atomizer including a heating element in fluid communication with the nicotine salt liquid formulation; and a fluid storage compartment for storing the nicotine salt liquid formulation.

[0028] Provided herein is an electronic cigarette for generating an inhalable aerosol, the electronic cigarette comprising: fluid storage compartment; heater; and a nicotine salt liquid formulation in a fluid storage compartment comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is characterized by a vapor pressure of greater than 20 mmHg at 200°C; Battery; and Includes a mouthpiece.

[0029] Provided herein is an electronic cigarette for generating an inhalable aerosol, the electronic cigarette comprising: fluid storage compartment; heater; and a nicotine salt liquid formulation in a fluid storage compartment comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is characterized by a vapor pressure of about 20 to 200 mmHg at 200°C; Battery; and Includes a mouthpiece.

[0030] Provided herein is an electronic cigarette for generating an inhalable aerosol, the electronic cigarette comprising: fluid storage compartment; heater; and a nicotine salt liquid formulation in a fluid storage compartment comprising a nicotine salt in a biologically acceptable liquid carrier, wherein an acid used to form the nicotine salt is further characterized by a melting point below 160°C, a boiling point above 160°C, and a difference of at least 50 degrees between the melting point and the boiling point; Battery; and Includes a mouthpiece.

[0031] Provided herein is an electronic cigarette for generating an inhalable aerosol, the electronic cigarette comprising: fluid storage compartment; heater; and a nicotine salt liquid formulation in a fluid storage compartment, comprising a nicotine salt in a biologically acceptable liquid carrier, wherein an acid used to form the nicotine salt is further characterized by a melting point at least 40 degrees below the operating temperature of the electronic cigarette, a boiling point no more than 40 degrees below the operating temperature of the electronic cigarette, and a difference of at least 50 degrees between the melting point and the boiling point; Battery; and Includes a mouthpiece.

[0032] Provided herein is a cartridge for an electronic cigarette that includes a fluid storage compartment, the fluid storage compartment storing a nicotine salt liquid formulation that includes a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is characterized by a vapor pressure of greater than 20 mmHg at 200°C.

[0033] Provided herein is a cartridge for an electronic cigarette that includes a fluid storage compartment, the fluid storage compartment storing a nicotine salt liquid formulation that includes a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is characterized by a vapor pressure of about 20 to 200 mmHg at 200°C.

[0034] Provided herein is a cartridge within an electronic cigarette that includes a fluid storage compartment, the fluid storage compartment storing a nicotine salt liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is further characterized by a melting point below 160°C, a boiling point above 160°C, and a difference of at least 50 degrees between the melting point and the boiling point.

[0035] Provided herein is a cartridge within an electronic cigarette that includes a fluid storage compartment, the fluid storage compartment storing a nicotine salt liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is further characterized by a melting point at least 40 degrees below the operating temperature of the electronic cigarette, a boiling point that is no more than 40 degrees below the operating temperature of the electronic cigarette, and a difference of at least 50 degrees between the melting point and the boiling point.

[0036] A kit is provided herein, the kit comprising: (a) An electronic cigarette for generating an inhalable aerosol, comprising: i. a device body including a cartridge container; ii. A cartridge comprising a fluid storage compartment, the fluid storage compartment storing a nicotine salt liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein an acid used to form the nicotine salt is characterized by a vapor pressure of greater than 20 mmHg at 200°C; iii.Heater; iv. Batteries; and v. Mouthpieces, including electronic cigarettes, as well as (b) instructions for using the e-cigarette to generate an inhalable aerosol.

[0037] A kit is provided herein, the kit comprising: (a) An electronic cigarette for generating an inhalable aerosol, comprising: i. a device body including a cartridge container; ii. A cartridge comprising a fluid storage compartment, the fluid storage compartment storing a nicotine salt liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is characterized by a vapor pressure of about 20 to 200 mmHg at 200°C; iii.Heater; iv. Batteries; and v. Mouthpieces, including electronic cigarettes, as well as (b) instructions for using the e-cigarette to generate an inhalable aerosol.

[0038] A kit is provided herein, the kit comprising: (a) An electronic cigarette for generating an inhalable aerosol, comprising: i. a device body including a cartridge container; ii. A cartridge comprising a fluid storage compartment, the fluid storage compartment storing a nicotine salt liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein an acid used to form the nicotine salt is further characterized by a melting point below 160°C, a boiling point above 160°C, and a difference of at least 50 degrees between the melting point and the boiling point; iii.Heater; iv. Batteries; and v. Mouthpieces, including electronic cigarettes, as well as (b) instructions for using the e-cigarette to generate an inhalable aerosol.

[0039] A kit is provided herein, the kit comprising: (a) An electronic cigarette for generating an inhalable aerosol, comprising: i. a device body including a cartridge container; ii. A cartridge comprising a fluid storage compartment, the fluid storage compartment storing a nicotine salt liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is further characterized by a melting point at least 40 degrees below the operating temperature of the electronic cigarette, a boiling point no more than 40 degrees below the operating temperature of the electronic cigarette, and a difference between the melting point and the boiling point of at least 50 degrees; iii.Heater; iv. Batteries; and v. Mouthpieces, including electronic cigarettes, as well as (b) instructions for using the e-cigarette to generate an inhalable aerosol.

[0040] <Incorporated by reference> All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference. [Brief explanation of the drawings]

[0041] A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which:

[0042] [Figure 1] Figure 1 shows the resulting heart rate data measured for 6 minutes from the start of the puff. The Y-axis is heart rate (bpm) and the X-axis represents the duration of the test (-60 to 180 seconds). [Figure 2] Figure 2 shows the resulting heart rate data measured for 10 minutes from the start of the puff. The Y-axis is heart rate (bpm) and the X-axis represents the duration of the test (0 to 10 minutes). [Figure 3] FIG. 3 shows the calculated vapor pressure of various acids relative to nicotine. [Figure 4] Figure 4 shows the pharmacokinetic profiles for the eight test articles in the plasma study. [Figure 5] Figure 5 shows a comparison of Cmax and Tmax for the eight test articles in the plasma study. [Figure 6] Figure 6 shows a comparison of Cmax and AUC for the eight test articles in the plasma study. [Figure 7] 7 illustrates one embodiment of an electronic cigarette having a fluid storage compartment containing a nicotine salt formulation of an embodiment described herein; and [Figure 8] FIG. 8 shows one embodiment of a cartomizer for an electronic cigarette having a fluid storage compartment, a heater, and containing a nicotine salt formulation of an embodiment described herein. DETAILED DESCRIPTION OF THE INVENTION

[0043] When provided to an individual or animal, nicotine is a chemical stimulant that increases heart rate and blood pressure. Nicotine delivery to an individual is associated with physical and / or emotional satisfaction. Conflicting reports have been published regarding the delivery efficiency of free-base nicotine compared to mono- or di-protonated nicotine salts. Studies on the delivery efficiency of free-base nicotine and nicotine salts have been complex and have yielded unpredictable results. Furthermore, these delivery efficiency studies have been conducted under very high-temperature conditions comparable to smoking; therefore, they provide insufficient guidance regarding the delivery efficiency of free-base nicotine and nicotine salts under low-temperature vaporization conditions. Some reports hypothesize that nicotine free base should produce more satisfaction in users than any corresponding nicotine salt.

[0044] It has been unexpectedly discovered herein that certain nicotine salt formulations provide superior satisfaction in individuals than that of nicotine free base, comparable to satisfaction in individuals smoking conventional cigarettes. The satisfaction effect is consistent with efficient delivery of nicotine to the individual's lungs and a rapid increase in nicotine absorption in plasma, as shown, for non-limiting examples, at least in Example 8. It has also been unexpectedly discovered herein that certain nicotine salt formulations provide greater satisfaction than other nicotine salt formulations, and such effect is shown, for non-limiting examples, in the plasma levels of exemplary nicotine salt formulations herein. These results indicate that although some nicotine salt formulations aerosolized by e-cigarettes exhibit different blood nicotine uptake rates, faster than other aerosolized nicotine salt formulations and also faster than nicotine free base formulations, the peak blood nicotine concentrations and total amount of nicotine delivered appear comparable to conventional cigarettes and do not appear to differ significantly among the various nicotine formulations. Thus, described herein are nicotine salt formulations for use in e-cigarettes and the like that provide a generally satisfying effect consistent with efficient delivery of nicotine to an individual's lungs and a rapid rise in nicotine absorption in the plasma. Accordingly, provided herein are devices, nicotine salts, systems, cartomizers, kits, and methods used to inhale, via the mouth or nose, an aerosol generated from a nicotine salt liquid formulation as described herein or as would be apparent to one of skill in the art upon reading this disclosure.

[0045] Consistent with these satisfaction effects, plasma nicotine levels measured from free-base nicotine formulations inhaled using low-temperature vaporizers, i.e., e-cigarettes, were significantly higher than those of conventional cigarettes. max and T max (which also measured plasma nicotine levels) compared with C max (maximum concentration) and T maxFurthermore, consistent with these satisfaction effects, plasma nicotine levels measured for free base nicotine formulations inhaled using low-temperature vaporizers or e-cigarettes were unexpectedly found to be significantly different from the C of nicotine salt formulations inhaled using electronic low-temperature vaporizers or e-cigarettes. max and T max (which also measured plasma nicotine levels) compared with C max (maximum concentration) and T max It has been unexpectedly found that there are differences between the plasma nicotine uptake rates (times at which maximum concentrations are measured) of users who inhale free-base nicotine formulations using cold vaporization devices, i.e., e-cigarettes, compared to the plasma nicotine uptake rates of users who inhale conventional cigarette smoke.It has also been unexpectedly found that there are differences between the plasma nicotine uptake rates of users who inhale free-base nicotine formulations using cold vaporization devices, i.e., e-cigarettes, compared to the plasma nicotine uptake rates of users who inhale nicotine salt formulations using cold vaporization devices, i.e., e-cigarettes.

[0046] Thus, when looking at free base nicotine as a source of nicotine in compositions used in e-cigarettes, the delivery of nicotine to the blood of free base nicotine compositions when inhaled using an e-cigarette is related to plasma levels (C max and T max ) does not necessarily match the nicotine delivery of conventional cigarettes upon inhalation. The delivery of nicotine to the blood of free base nicotine compositions upon inhalation is at plasma levels (C max and T max ) does not necessarily compare to the nicotine delivery of nicotine salt formulations upon inhalation. The delivery of nicotine to the blood of free base nicotine compositions upon inhalation is significantly higher than the plasma levels (C) when measuring the rate of nicotine uptake in the blood within the first 0-5 minutes. max and T max) does not necessarily match the nicotine delivery of conventional cigarettes upon inhalation. The delivery of nicotine to the blood of free base nicotine compositions upon inhalation does not necessarily match, at plasma levels, the delivery of nicotine from nicotine salt formulations upon inhalation when measuring the rate of nicotine uptake in the blood within the first 0-5 minutes.

[0047] Furthermore, consistent with these satisfaction effects, the C of nicotine salt formulations inhaled using low-temperature vaporizers, i.e., e-cigarettes, max and T max (measuring plasma nicotine levels) is C max and T max Although the plasma nicotine uptake rates appear comparable to those of other nicotine salts (also measured using plasma nicotine levels), it was unexpectedly found that there are distinct differences in the plasma nicotine uptake rates of users who inhale certain nicotine salt formulations using cold vaporization devices or e-cigarettes compared to users who inhale other nicotine salt formulations using cold vaporization devices or e-cigarettes. max and T max It is also unexpected that, while the absorption rate of nicotine in the plasma of a user's blood is comparable to (or close to) that of a conventional cigarette, certain nicotine salt formulations exhibit greater rates of nicotine uptake in the plasma of the user's blood than conventional cigarettes. Nicotine salt formulations exhibiting the fastest rates of nicotine uptake in the plasma were more favored in satisfaction ratings and rated as equivalent to cigarette satisfaction than nicotine salt formulations exhibiting the slowest rates of rise in nicotine in the subject's plasma. Furthermore, doubling the concentration of nicotine salt in a formulation does not necessarily affect the rate of nicotine absorption in the blood (see non-limiting example Example 8, nicotine benzoate tested at 2% and 4% concentrations).

[0048] Therefore, when we look at the nicotine salt formulations used in e-cigarettes, the nicotine salt formulations delivered using e-cigarettes are C max and T maxWhile not all nicotine salts behave similarly (as measured by plasma nicotine levels), they appear comparable to each other and to conventional cigarettes in terms of initial (0-1.5 minute) blood nicotine uptake rates. These results are unexpected. Nicotine salt formulations made with acids having vapor pressures between 20-300 mmHg at 200°C, or >20 mmHg at 200°C, or 20 to 300 mmHg at 200°C, or 20 to 200 mmHg at 200°C, or between 20 and 300 mmHg at 200°C, appear to have faster initial (non-limiting examples: 0-1.5 minutes, 0-3 minutes, 0-2 minutes, 0-4 minutes) blood nicotine uptake rates than other nicotine salt formulations, but also provide a sensation comparable to or close to that of conventional cigarettes (compared to other nicotine salt formulations or to nicotine free base formulations). Non-limiting examples of acids that meet one or more of the criteria in the preceding sentence include salicylic acid, sorbic acid, benzoic acid, lauric acid, and levulinic acid. Nicotine salt formulations made with acids having a difference between their boiling point and melting point of at least 50°C, a boiling point greater than 160°C, and a melting point less than 160°C, appear to have a faster initial rate of nicotine uptake in the blood (non-limiting examples being 0-1.5 minutes, 0-3 minutes, 0-2 minutes, and 0-4 minutes) than other nicotine salt formulations, while also providing a sensation comparable to or closer to that of conventional cigarettes (compared to other nicotine salt formulations or to nicotine free base formulations). Non-limiting examples of acids that meet the criteria in the preceding sentence include salicylic acid, sorbic acid, benzoic acid, pyruvic acid, lauric acid, and levulinic acid. Nicotine salt formulations made with acids having a difference between their boiling and melting points of at least 50°C, and having boiling points up to 40°C lower than the actuation temperature, and having melting points up to 40°C lower than the actuation temperature, appear to have a faster initial rate of nicotine uptake in the blood (for non-limiting examples, 0-1.5 minutes, 0-3 minutes, 0-2 minutes, 0-4 minutes) than other nicotine salt formulations, but also provide a sensation comparable to or closer to that of a conventional cigarette (compared to other nicotine salt formulations or compared to nicotine free base formulations).The operating temperature can be 100°C to 300°C, or about 200°C, about 150°C to about 250°C, 180°C to 220°C, about 180°C to about 220°C, 185°C to 215°C, about 185°C to about 215°C, about 190°C to about 210°C, 190°C to 210°C, 195°C to 205°C, or about 195°C to about 205°C. By way of non-limiting example, acids meeting one or more criteria in the preceding sentence include salicylic acid, sorbic acid, benzoic acid, pyruvic acid, lauric acid, and levulinic acid. Combinations of these criteria for preference of a particular nicotine salt formulation are contemplated herein.

[0049] However, other reasons for excluding a particular acid from a formulation may be unrelated to the rate of nicotine uptake. For example, the acid may be unsuitable for use with the device's materials (corrosive or otherwise incompatible). Sulfuric acid is one example of this, which may be unsuitable for e-cigarette devices. The acid may be unsuitable for inhalation use or for toxicological reasons—and therefore incompatible for human consumption, ingestion, or inhalation. Sulfuric acid is another example of this, which may be unsuitable for e-cigarette devices, depending on the embodiment of the composition. Bitter or otherwise unpleasant taste may also provide a reason for exclusion, such as acetic acid in some embodiments. Acids that oxidize at room or operating temperatures may be unsuitable for certain embodiments, such as sorbic acid, because they exhibit decomposition, reaction, or instability that may be undesirable in the formulation. The decomposition of the acid at room or operating temperatures indicates that the acid is unsuitable for use in the example formulations. For example, citric acid decomposes at 175°C and malic acid decomposes at 140°C, so for devices operating at 200°C, these acids may not be suitable. Acids with poor solubility in the compositional components may be unsuitable for use in certain embodiments of the compositions herein. For example, nicotine bitartrate, with a nicotine and tartaric acid composition in a 1:2 molar ratio, will not produce more than 0.5% (w / w) nicotine and more than 0.9% (w / w) tartaric acid in propylene glycol (PG) or vegetable glycerin (VG) or any mixture of PG and VG at ambient conditions. As used herein, weight percent (w / w) refers to the weight of an individual component over the total weight of the formulation.

[0050] Also, as used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0051] As used herein, the term "organic acid" refers to an organic compound that has acidic properties (e.g., according to the Bronsted-Lowry or Lewis definitions). Common organic acids are carboxylic acids, whose acidity is related to their carboxyl group—COOH. Dicarboxylic acids have two carboxylic acid groups. The relative acidity of an organic substance is measured by its pKa value, and those skilled in the art know how to determine the acidity of an organic acid based on a given pKa value. As used herein, the term "keto acid" refers to an organic compound containing a carboxylic acid group and a ketone group. Common types of keto acids include alpha-keto acids or 2-oxo acids, such as pyruvic acid or oxaloacetic acid; beta-keto acids or 3-oxo acids, such as acetoacetic acid; gamma-keto acids or 4-oxo acids, such as levulinic acid; and ketone groups on the third carbon atom from the carboxylic acid.

[0052] As used herein, the terms "electronic cigarette" or "e-cigarette" or "low-temperature vaporizer" refer to an electronic inhaler that vaporizes a liquid solution into an aerosol mist, simulating the act of smoking a cigarette. The liquid solution contains a formulation that includes nicotine. Many electronic cigarettes bear no resemblance to traditional cigarettes. The amount of nicotine contained can be selected by the user via inhalation. Generally, electronic cigarettes contain three essential components: a plastic cartridge that serves as a mouthpiece and liquid reservoir, an "atomizer" that vaporizes the liquid, and a battery. In other embodiments, electronic cigarettes include a combined atomizer and reservoir called a "cartomizer," which may or may not be disposable, a mouthpiece that may or may not be integrated with the cartomizer, and a battery.

[0053] As used in this specification and claims, unless otherwise specified, the term "about" means a variation of 1%, 2%, 3%, 4%, 5%, 10%, 15%, or 25%, depending on the embodiment.

[0054] Suitable carriers (e.g., liquid solvents) for the nicotine salts described herein include media in which the nicotine salt is soluble at ambient conditions, such that the nicotine salt does not form a solid precipitate. Examples include, but are not limited to, glycerol, propylene glycol, trimethylene glycol, water, ethanol, and the like, as well as combinations thereof. In some embodiments, the liquid carrier comprises 0% to 100% propylene glycol and 100% to 0% vegetable glycerin. In some embodiments, the liquid carrier comprises 10% to 70% propylene glycol and 90% to 30% vegetable glycerin. In some embodiments, the liquid carrier comprises 20% to 50% propylene glycol and 80% to 50% vegetable glycerin. In some embodiments, the liquid carrier comprises 30% propylene glycol and 70% vegetable glycerin.

[0055] The formulations described herein vary in concentration. Some formulations utilize a dilute concentration of nicotine salt in a carrier. Some formulations utilize a less dilute concentration of nicotine salt in a carrier. In some formulations, the concentration of nicotine in the nicotine salt formulation is about 1% (w / w) to about 25% (w / w). In some formulations, the concentration of nicotine in the nicotine salt formulation is about 1% (w / w) to about 20% (w / w). In some formulations, the concentration of nicotine in the nicotine salt formulation is about 1% (w / w) to about 18% (w / w). In some embodiments, the concentration of nicotine in the nicotine salt formulation is about 1% (w / w) to about 15% (w / w). In some formulations, the concentration of nicotine in the nicotine salt formulation is about 4% (w / w) to about 12% (w / w). In some formulations, the concentration of nicotine in the nicotine salt formulation is about 4% (w / w). In some embodiments, the concentration of nicotine in the nicotine salt formulation is about 2% (w / w). In some formulations, the concentration of nicotine in the nicotine salt formulation is 1% (w / w) to 25% (w / w). In some formulations, the concentration of nicotine in the nicotine salt formulation is 1% (w / w) to 20% (w / w). In some formulations, the concentration of nicotine in the nicotine salt formulation is 1% (w / w) to 18% (w / w). In some formulations, the concentration of nicotine in the nicotine salt formulation is 1% (w / w) to 15% (w / w). In some formulations, the concentration of nicotine in the nicotine salt formulation is about 4% (w / w) to 12% (w / w). In some formulations, the concentration of nicotine in the nicotine salt formulation is 4%. In some formulations, the concentration of nicotine in the nicotine salt formulation is 2%. In some formulations, one nicotine salt with a low dilution concentration is used in combination with a second nicotine salt with a higher dilution concentration. In some formulations, the nicotine concentration in a first nicotine salt formulation is from about 1% to about 20% and is combined with a second nicotine salt formulation having a nicotine concentration of from about 1% to about 20%, or any range or concentration. In some formulations, the nicotine concentration in a first nicotine salt formulation is from 1% to 20% and is combined with a second nicotine salt formulation having a nicotine concentration of from 1% to 20%, or any range or concentration.The term "about," when used in reference to the concentration of nicotine in a nicotine salt formulation, may, in some embodiments, mean a range of 0.05% (i.e., if the concentration is about 2%, the range is 1.95%-2.05%), 0.1 (i.e., if the concentration is about 2%, the range is 1.9%-2.1%), 0.25 (i.e., if the concentration is about 2%, the range is 1.75%-2.25%), 0.5 (i.e., if the concentration is about 2%, the range is 1.5%-2.5%), or 1 (i.e., if the concentration is about 4%, the range is 3%-5%).

[0056] Nicotine salts are formed by the addition of a suitable acid, including organic or inorganic acids. In some formulations provided, the suitable organic acid is a carboxylic acid. Examples of organic carboxylic acids disclosed herein include monocarboxylic acids, dicarboxylic acids (organic acids containing two carboxylic acid groups), carboxylic acids containing aromatic groups (benzoic acid, hydroxycarboxylic acids, heterocyclic carboxylic acids, terpenoid acids, sugar acids, etc.), such as pectinic acid, amino acids, cycloaliphatic acids, aliphatic carboxylic acids, ketocarboxylic acids, etc. In some formulations provided herein, the organic acid used herein is a monocarboxylic acid. Nicotine salts are formed by the addition of a suitable acid to nicotine. In some formulations provided herein, the stoichiometric ratio of nicotine to acid (nicotine: acid) is 1:1, 1:2, 1:3, 1:4, 2:3, 2:5, 2:7, 3:4, 3:5, 3:7, 3:8, 3:10, 3:11, 4:5, 4:7, 4:9, 4:10, 4:11, 4:13, 4:14, 4:15, 5:6, 5:7, 5:8, 5:9, 5:11, 5:12, 5:13, 5:14, 5:16, 5:17, 5:18, or 5:19. In some formulations provided herein, the stoichiometric ratio of nicotine to acid is 1:1, 1:2, 1:3, or 1:4 (nicotine: acid).

[0057] Nicotine is an alkaloid molecule that contains two basic nitrogens. It can occur in different states of protonation. For example, when there is no protonation, nicotine is called the "free base." When one nitrogen is protonated, nicotine is "monoprotonated."

[0058] Nicotine salt formulations can be formed by adding a suitable acid to nicotine, stirring the neat mixture at ambient temperature or at an elevated temperature, and then diluting the neat mixture with a carrier mixture, such as a mixture of propylene glycol and glycerin. In some embodiments, the suitable acid is completely dissolved in the nicotine prior to dilution. In some embodiments, the suitable acid may not be completely dissolved in the nicotine prior to dilution. The addition of the suitable acid to nicotine to form the neat mixture may cause an exothermic reaction. The addition of the suitable acid to nicotine to form the neat mixture may be performed at 55°C. The addition of the suitable acid to nicotine to form the neat mixture may be performed at 90°C. The neat mixture may be cooled to ambient temperature prior to dilution. The dilution may be performed at an elevated temperature.

[0059] Nicotine salt formulations can be prepared by combining nicotine and a suitable acid in a carrier mixture, such as a mixture of propylene glycol and glycerin. The mixture of nicotine and a first carrier mixture is combined with a suitable acid mixture in a second carrier mixture. In some embodiments, the first and second carrier mixtures are identical in composition. In some embodiments, the first and second carrier mixtures are not identical in composition. In some embodiments, heating the nicotine / acid / carrier mixture is necessary to promote complete dissolution.

[0060] In some embodiments, the nicotine salt formulations may be prepared and added to a solution of propylene glycol (PG) / vegetable glycerin (VG) in a 3:7 weight ratio and thoroughly mixed. Although described herein as producing 10 g of each formulation, all procedures described below are scalable. As will be known to those skilled in the art upon reading the disclosure herein, other methods of formulation may also be used to form the formulations described below without departing from the disclosure herein.

[0061] The optimal nicotine salt formulation may be determined by the vapor pressure of the constituent acids. In some embodiments, the nicotine salt formulation includes an acid with a vapor pressure similar to that of free base nicotine. In some embodiments, the nicotine salt formulation is formed from an acid with a vapor pressure similar to that of free base nicotine at the heating temperature of the device. Figure 3 illustrates this trend. Nicotine salts formed from nicotine and benzoic acid; nicotine and salicylic acid; or nicotine and levulinic acid are salts that produce a satisfying effect in the user consistent with efficient delivery of nicotine and a rapid rise in nicotine plasma levels. This pattern may be due to the mechanism of action during heating of the nicotine salt formulation. The nicotine salt may dissociate at or slightly below the heating temperature of the device, resulting in a mixture of free base nicotine and the individual acid. In that regard, if both nicotine and the acid have similar vapor pressures, they may be aerosolized simultaneously, resulting in delivery of both free base nicotine and the constituent acid to the user.

[0062] Nicotine salt liquid formulations for generating an inhalable aerosol upon heating in an electronic cigarette may include a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is characterized by a vapor pressure of 20-4000 mmHg at 200° C. In some embodiments, the acid used to form the nicotine salt is characterized by a vapor pressure of between 20-2000 mmHg at 200° C. In some embodiments, the acid used to form the nicotine salt is characterized by a vapor pressure of between 100-300 mmHg at 200° C.

[0063] Unexpectedly, different nicotine salt formulations varied in satisfaction among individuals. In some embodiments, the degree of protonation of the nicotine salt affected satisfaction, such that more protonated nicotine salts provided less satisfaction compared to less protonated nicotine salts. The nicotine salts formed may be monoprotonated. The nicotine salts formed may be diprotonated. The nicotine salts may exist in more than one protonation state (e.g., an equilibrium between monoprotonated and diprotonated nicotine salts). The degree of protonation of the nicotine molecule may depend on the stoichiometric ratio of nicotine:acid used in the salt formation reaction. The degree of protonation of the nicotine molecule may depend on the solvent. The degree of protonation of the nicotine molecule may be unknown. In some embodiments, monoprotonated nicotine salts provided high user satisfaction. For example, nicotine benzoate and nicotine salicylate are nicotine salts in which the protons are monoprotonated, all of which provide high user satisfaction. The reason for this trend may be explained by the mechanism of action, in which nicotine is first deprotonated with the constituent acid before delivery into the vapor, then retained and stabilized after reprotonation as the acid migrates downstream to the user's lungs. It may be easier to remove one proton for every two, thus resulting in better delivery efficiency. Furthermore, the lack of satiability of free-base nicotine suggests that other factors are important. Depending on the salt, nicotine salts may perform best when in their optimal protonation range. For example, nicotine pyruvate is a nicotine salt with a nicotine:acid ratio of 1:2. A formulation containing nicotine pyruvate (1:2) may provide greater satiability to the user than a formulation with the same amount of nicotine but half the amount of pyruvate, such as nicotine pyruvate (1:1). This may be explained by the fact that one mole of nicotine produces two moles of pyruvate and a salt. If there is not enough pyruvate to associate with all the nicotine molecules, the free base nicotine formulation will remain unprotonated, which can reduce the satisfaction that the formulation provides.

[0064] The flavor of the constituent acids used in the salt formation may be considered when selecting the acid. Suitable acids are non-toxic or minimally toxic to humans at the concentrations used. Suitable acids may be compatible with the components of the e-cigarette that they will or may come into contact with at the concentration used. That is, such acids do not decompose or otherwise react with the components of the e-cigarette that they will or may come into contact with. The odor of the constituent acids used in the salt formation may be considered when selecting the appropriate acid. The concentration of the nicotine salt in the carrier may affect the satisfaction of an individual user. In some embodiments, the flavor of the formulation is adjusted by varying the acid. In some embodiments, the flavor of the formulation is adjusted by adding an exogenous flavoring agent. In some embodiments, an acid with an unpleasant taste or odor is used in a minimal amount to ameliorate such characteristics. In some embodiments, an exogenous acid with a pleasant odor or taste is added to the formulation. Examples of salts that can provide flavor and aroma to mainstream aerosol at certain levels include nicotine acetate, nicotine oxalate, nicotine malate, nicotine isovalerate, nicotine lactate, nicotine citrate, nicotine phenylacetate, and nicotine myristate.

[0065] The nicotine salt formulation may generate an inhalable aerosol upon heating in the electronic cigarette. The amount of nicotine or nicotine salt aerosol inhaled may be determined by the user. The user may vary the amount of nicotine or nicotine salt inhaled, for example, by adjusting the intensity of their inhalation.

[0066] Described herein are formulations comprising two or more nicotine salts. In some embodiments where the formulation comprises two or more nicotine salts, each of the individual nicotine salts is formed as described herein.

[0067] As used herein, a nicotine salt formulation refers to a single or mixture of nicotine salts with other suitable chemical components used in e-cigarettes, such as carriers, stabilizers, diluents, dispersants, suspending agents, thickeners, and / or excipients. In some embodiments, the nicotine salt formulation is stirred at ambient conditions for 20 minutes. In some embodiments, the nicotine salt formulation is heated and stirred at 55°C for 20 minutes. In some embodiments, the nicotine salt formulation is heated and stirred at 90°C for 60 minutes. In some embodiments, the formulation facilitates administration of nicotine to tissues (e.g., lungs).

[0068] The nicotine in the nicotine salt formulations provided herein is either naturally occurring nicotine (e.g., from extracts of nicotineous species such as tobacco) or synthetic nicotine. In some embodiments, it is (-)-nicotine, (+)-nicotine, or a mixture thereof. In some embodiments, nicotine is used in a relatively pure form (e.g., greater than about 80% pure, about 90% pure, about 85% pure, about 95% pure, or about 99% pure). In some embodiments, the nicotine in the nicotine salt formulations provided herein is "water clear" in appearance to avoid or minimize the formation of tar residue during the subsequent salt formation process.

[0069] In some embodiments, the nicotine salt formulations used in the electronic cigarettes described herein have a nicotine concentration of about 0.5% (w / w) to about 20% (w / w), where the concentration is nicotine by total solution weight, i.e., (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of about 1% (w / w) to about 20% (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of about 1% (w / w) to about 18% (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of about 1% (w / w) to about 15% (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of about 4% (w / w) to about 12% (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of about 1% (w / w) to about 18% (w / w), about 3% (w / w) to about 15% (w / w), or about 4% (w / w) to about 12% (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of about 0.5% (w / w) to about 10% (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of about 0.5% (w / w) to about 5% (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of about 0.5% (w / w) to about 4% (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of about 0.5% (w / w) to about 4% (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of about 0.5% (w / w) to about 3% (w / w). 5% to about 3% (w / w) (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of about 0.5% (w / w) to about 2% (w / w). 5% to about 2% (w / w) (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of about 0.5% (w / w) to about 1% (w / w). 5% to about 1% (w / w) (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of about 1% (w / w) to about 10% (w / w).In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of about 1% (w / w) to about 5% (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of about 1% (w / w) to about 4% (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of about 1% (w / w) to about 3% (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of about 1% (w / w) to about 2% (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of about 2% (w / w) to about 10% (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of about 2% (w / w) to about 5% (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of about 2% (w / w) to about 4% (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of about 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3.0%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4.0%, 4.10%, 4.11%, 4.12%, 4.13%, 4.14%, 4.15%, 4.16%, 4.17%, 4.18%, 4.19%, 4.20%, 4.21%, 4.22%, 4.23%, 4.24%, 4.25%, 4.26%, 4.27%, 4.28%, 4.29%, 4.30%, 4.31%, 4.32%, 4.33%, 4.34%, 4.35%, 4.36%, 4.37%, 4.38%, 4.39%, 4.40%, 4.41%, 4.42%, 4.43%, 4.44%, 4.45%, 4.46%, 4.47%, 4.48%, 4.49%, 4.50%, 4.51%, 4.52%, 4.53%, 4. nicotine salt formulations having a nicotine concentration of about 0.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, 6.5%, 7.0%, 7.5%, 8.0%, 8.5%, 9.0%, 9.5%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20% (w / w) or more, including any increment therein. Certain embodiments provide nicotine salt formulations having a nicotine concentration of about 5% (w / w). Certain embodiments provide nicotine salt formulations having a nicotine concentration of about 4% (w / w). Certain embodiments provide nicotine salt formulations having a nicotine concentration of about 3% (w / w). Certain embodiments provide nicotine salt formulations having a nicotine concentration of about 2% (w / w). Certain embodiments provide nicotine salt formulations having a nicotine concentration of about 1% (w / w).Certain embodiments provide nicotine salt formulations having a nicotine concentration of about 0.5% (w / w).

[0070] The formulation may further include one or more flavoring agents.

[0071] Suitable acids for nicotine salt formulations may have a vapor pressure of >20 mmHg at 200° C. and are not corrosive to e-cigarettes or toxic to humans. In some embodiments, acids suitable for forming nicotine salts are selected from the group consisting of salicylic acid, formic acid, sorbic acid, acetic acid, benzoic acid, pyruvic acid, lauric acid, and levulinic acid.

[0072] Suitable acids for nicotine salt formulations may have a vapor pressure of 20-200 mmHg at 200° C. and are not corrosive to e-cigarettes or toxic to humans. In some embodiments, acids suitable for forming nicotine salts are selected from the group consisting of salicylic acid, benzoic acid, lauric acid, and levulinic acid.

[0073] Acids suitable for nicotine salt formulations have a melting point <160°C, a boiling point >160°C, and may have a difference between their melting and boiling points of at least 50 degrees, and are not corrosive to e-cigarettes or non-toxic to humans. In some embodiments, acids suitable for forming nicotine salts have a melting point at least 40 degrees below the operating temperature of an e-cigarette, a boiling point no more than 40 degrees below the operating temperature of an e-cigarette, and a difference between their melting and boiling points of at least 50 degrees, and are not corrosive to e-cigarettes or non-toxic to humans, where the operating temperature is 200°C. In some embodiments, acids suitable for forming nicotine salts are selected from the group consisting of salicylic acid, sorbic acid, benzoic acid, pyruvic acid, lauric acid, and levulinic acid.

[0074] Acids suitable for nicotine salt formulations do not decompose at the operating temperatures of electronic cigarettes. In some embodiments, acids suitable for forming nicotine salts do not oxidize at the operating temperatures of electronic cigarettes. In some embodiments, acids suitable for forming nicotine salts do not oxidize at room temperature. In some embodiments, acids suitable for forming nicotine salts do not provide an unpleasant taste. In some embodiments, acids suitable for forming nicotine salts have good solubility in liquid formulations used in electronic cigarettes.

[0075] Provided herein is an electronic cigarette 2 having a fluid storage compartment 4 containing a nicotine salt formulation of any embodiment described herein within the fluid storage compartment. An embodiment is shown in FIG. 7. The electronic cigarette 2 of FIG. 7 includes a mouth end 6 and a charging end 8. The mouth end 6 includes a mouthpiece 10. The charging end 8 may connect to a battery or a charger, or both, where the battery is within the body of the electronic cigarette and the charger is separate from the battery and couples to the body or the battery for charging the battery. In some embodiments, the electronic cigarette includes a rechargeable battery within the body 14 of the electronic cigarette, and the charging end 8 includes a connection 12 for charging the rechargeable battery. In some embodiments, the electronic cigarette includes a cartomizer containing the fluid storage compartment and an atomizer. In some embodiments, the atomizer includes a heater. In some embodiments, the fluid storage compartment 4 is separable from the atomizer. In some embodiments, the fluid storage compartment 4 is replaceable, such as part of a replaceable cartridge. In some embodiments, the fluid storage compartment 4 is refillable. In some embodiments, the mouthpiece 10 is interchangeable.

[0076] Provided herein is a cartomizer 18 for an electronic cigarette 2 having a fluid storage compartment 4 containing any of the nicotine salt formulations described herein within the fluid storage compartment. The cartomizer 18 embodiment of FIG. 8 includes a mouth end 6 and a connecting end 16. The connecting end 16 in the embodiment of FIG. 8 couples the cartomizer 14 to the body of the electronic cigarette, the electronic cigarette battery, or both. The mouth end 6 includes a mouthpiece 10. In some embodiments, the cartomizer does not include a mouthpiece; in such embodiments, the cartomizer may be coupled to the mouthpiece of the electronic cigarette, or the cartomizer may be coupled to the battery or the body of the electronic cigarette, but the mouthpiece may also be coupled to the battery or the body of the electronic cigarette. In some embodiments, the mouthpiece is integral with the body of the electronic cigarette. In some embodiments, including the embodiment of FIG. 8, the cartomizer 18 includes a fluid storage compartment 4 and an atomizer (not shown). In some embodiments, the atomizer includes a heater (not shown). [Example]

[0077] Example 1: Preparation of Nicotine Salt Formulations

[0078] Various nicotine formulations were prepared and added to a 3:7 weight ratio propylene glycol (PG) / vegetable glycerin (VG) solution and thoroughly mixed. The examples below were used to make 10 g of each formulation. All procedures were scalable.

[0079] For example, to make nicotine formulations with a final base equivalent concentration of 2% (w / w) nicotine free base, the following procedure was applied to each formulation. Nicotine benzoate salt formulation: 0.15 g of benzoic acid was added to a beaker, followed by 0.2 g of nicotine in the same beaker. The mixture was stirred at 55°C for 20 minutes until the benzoic acid was completely dissolved and an orange, oily mixture was formed. The mixture was cooled to ambient conditions. 9.65 g of a PG / VG (3:7) solution was added to the orange nicotine benzoate salt, and the mixture was stirred until a visually homogeneous formulation solution was obtained. A nicotine benzoate salt formulation can also be made by adding 0.15 g of benzoic acid to a beaker, followed by adding 0.2 g of nicotine and 9.65 g of PG / VG (3:7) solution to the same beaker. The mixture was then stirred at 55°C for 20 minutes until a visually homogeneous formulation solution was obtained, free of undissolved chemicals. A nicotine citrate formulation was made by adding 0.47g of citric acid to a beaker, followed by adding 0.2g of nicotine and 9.33g of PG / VG (3:7) solution to the same beaker. The mixture was then stirred at 90°C for 60 minutes until a visually homogenous formulation solution was obtained, free of undissolved chemicals. A formulation of nicotine-malate was made by adding 0.33 g of L-malic acid to a beaker, followed by adding 0.2 g and 9.47 g of PG / VG (3:7) solution to the same beaker. The mixture was then stirred at 90°C for 60 minutes until a visually homogeneous formulation solution was obtained, free of undissolved chemicals. A nicotine succinate formulation was made by adding 0.29 g of succinic acid to a beaker, followed by 0.2 g of nicotine and 9.51 g of a PG / VG (3:7) solution to the same beaker. The mixture was then stirred at 90°C for 60 minutes until a visually homogeneous formulation solution was obtained, free of undissolved chemicals. A nicotine salicylate formulation can be made by adding 0.17g of salicylic acid to a beaker, followed by adding 0.2g of nicotine and 9.63g of PG / VG (3:7) solution to the same beaker. The mixture is then stirred at 90°C for 60 minutes until a visually homogeneous formulation solution is obtained, free of undissolved chemicals. A nicotine salicylate formulation can also be made by adding 0.17 g of salicylic acid to a beaker, followed by 0.2 g of nicotine to the same beaker. The mixture was stirred at 90°C for 60 minutes until the salicylic acid was completely dissolved and an orange oily mixture was formed. The mixture was cooled to ambient conditions or held at 90°C when 9.63 g of PG / VG (3:7) solution was added. The mixture was then stirred at 90°C until a visually homogeneous formulation solution was obtained, free of undissolved chemicals. A nicotine free base formulation was made by adding 0.2 g of nicotine to a beaker followed by 9.33 g of PG / VG (3:7) solution to the same beaker, and then stirring the mixture at ambient conditions for 10 minutes until a visually homogeneous formulation solution was obtained.

[0080] For example, to make nicotine salt formulations with a final base equivalent concentration of 3% (w / w) nicotine free base, the following procedure was applied to each formulation. - Nicotine benzoate salt formulation: 0.23 g of benzoic acid was added to a beaker, followed by 0.3 g of nicotine to the same beaker. The mixture was stirred at 55°C for 20 minutes until the benzoic acid was completely dissolved and an orange oily mixture was formed. The mixture was cooled to ambient conditions. 9.47 g of PG / VG (3:7) solution was added to the orange nicotine benzoate salt, and the mixture was stirred until a visually homogeneous formulation solution was obtained. A nicotine benzoate salt formulation can also be made by adding 0.23 g of benzoic acid to a beaker, followed by adding 0.3 g of nicotine and 9.47 g of PG / VG (3:7) solution to the same beaker. The mixture was then stirred at 55°C for 20 minutes until a visually homogeneous formulation solution was obtained, free of undissolved chemicals. A nicotine citrate formulation was made by adding 0.71 g of citric acid to a beaker, followed by adding 0.3 g of nicotine and 8.99 g of a PG / VG (3:7) solution to the same beaker. The mixture was then stirred at 90°C for 60 minutes until a visually homogenous formulation solution was obtained, free of undissolved chemicals. A nicotine-malate formulation was made by adding 0.5 g of L-malic acid to a beaker, followed by adding 0.3 g of nicotine and 9.2 g of PG / VG (3:7) solution to the same beaker. The mixture was then stirred at 90°C for 60 minutes until a visually homogeneous formulation solution was obtained, free of undissolved chemicals. A nicotine levulinate salt formulation was made by adding 0.64 g of levulinic acid to a beaker, followed by 0.3 g of nicotine to the same beaker. The mixture was stirred at ambient conditions for 10 minutes. An exothermic reaction occurred, yielding an oily product. The mixture was cooled to ambient temperature, and 9.06 g of a PG / VG (3:7) solution was added to the same beaker. The mixture was then stirred at ambient conditions for 20 minutes until a visually homogeneous formulation solution was obtained. A nicotine pyruvate salt formulation was made by adding 0.33 g of pyruvic acid to a beaker, followed by 0.3 g of nicotine to the same beaker. The mixture was stirred at ambient conditions for 10 minutes. An exothermic reaction occurred, yielding an oily product. The mixture was cooled to ambient temperature, and 9.37 g of PG / VG (3:7) solution was added to the same beaker. The mixture was then stirred at ambient conditions for 20 minutes until a visually homogeneous formulation solution was obtained. A nicotine succinate formulation was made by adding 0.44 g of succinic acid to a beaker, followed by 0.3 g of nicotine and 9.26 g of a PG / VG (3:7) solution to the same beaker. The mixture was then stirred at 90°C for 60 minutes until a visually homogeneous formulation solution was obtained, free of undissolved chemicals. A nicotine salicylate formulation was made by adding 0.26 g of salicylic acid to a beaker, followed by 0.3 g of nicotine and 9.44 g of a PG / VG (3:7) solution to the same beaker. The mixture was then stirred at 90°C for 60 minutes until a visually homogeneous formulation solution was obtained, free of undissolved chemicals. A nicotine salicylate formulation can also be made by adding 0.26 g of salicylic acid to a beaker, followed by 0.3 g of nicotine to the same beaker. The mixture was stirred at 90°C for 60 minutes until the benzoic acid was completely dissolved and an orange oily mixture was formed. The mixture was cooled to ambient conditions or held at 90°C when 9.44 g of PG / VG (3:7) solution was added. The mixture was then stirred at 90°C until a visually homogeneous formulation solution was obtained, free of undissolved chemicals. A formulation of nicotine free base can also be made by adding 0.3 g of nicotine to a beaker followed by adding 9.7 g of PG / VG (3:7) solution to the same beaker, and then stirring the mixture at ambient conditions for 10 minutes until a visually homogeneous formulation solution was obtained.

[0081] For example, to make nicotine salt formulations with a final base equivalent concentration of 4% (w / w) nicotine free base, the following procedure was applied to each formulation. - Nicotine benzoate salt formulation: 0.3 g of benzoic acid was added to a beaker, followed by 0.4 g of nicotine to the same beaker. The mixture was stirred at 55°C for 20 minutes until the benzoic acid was completely dissolved and an orange oily mixture was formed. The mixture was cooled to ambient conditions. 9.7 g of PG / VG (3:7) solution was added to the orange nicotine benzoate salt, and the mixture was stirred until a visually homogeneous formulation solution was obtained. A nicotine benzoate salt formulation can also be made by adding 0.3 g of benzoic acid to a beaker, followed by adding 0.4 g of nicotine and 9.7 g of PG / VG (3:7) solution to the same beaker. The mixture was then stirred at 55°C for 20 minutes until a visually homogeneous formulation solution was obtained, free of undissolved chemicals. For example, to make nicotine salt formulations with a final base equivalent concentration of 5% (w / w) nicotine free base, the following procedure was applied to each formulation. Nicotine benzoate salt formulation: 0.38 g of benzoic acid was added to a beaker, followed by 0.5 g of nicotine to the same beaker. The mixture was stirred at 55° C. for 20 minutes until the benzoic acid was completely dissolved and an orange oily mixture was formed. The mixture was cooled to ambient conditions. 9.12 g of PG / VG (3:7) solution was added to the orange nicotine benzoate salt, and the mixture was stirred until a visually homogeneous formulation solution was obtained. A nicotine benzoate salt formulation was made by adding 0.38 g of benzoic acid to a beaker, followed by the addition of 0.5 g of nicotine and 9.12 g of a PG / VG (3:7) solution to the same beaker. The mixture was then stirred at 55°C for 20 minutes until a visually homogeneous formulation solution was obtained, free of undissolved chemicals. A nicotine-malate formulation was made by adding 0.83 g of L-malic acid to a beaker, followed by the addition of 0.5 g of nicotine and 8.67 g of a PG / VG (3:7) solution to the same beaker. The mixture was then stirred at 90°C for 60 minutes until a visually homogeneous formulation solution was obtained, free of undissolved chemicals. A nicotine levulinate salt formulation was also made by adding 1.07 g of levulinic acid to a beaker, followed by 0.5 g of nicotine to the same beaker. The mixture was stirred at ambient conditions for 10 minutes. An exothermic reaction occurred, yielding an oily product. The mixture was cooled to ambient temperature, and 8.43 g of a PG / VG (3:7) solution was added to the same beaker. The mixture was then stirred at ambient temperature for 20 minutes until a visually homogeneous formulation solution was obtained. A nicotine pyruvate salt formulation was made by adding 0.54 g of pyruvic acid to a beaker, followed by 0.5 g of nicotine to the same beaker. The mixture was stirred at ambient conditions for 10 minutes. An exothermic reaction occurred, yielding an oily product. The mixture was cooled to ambient temperature, and 8.96 g of a PG / VG (3:7) solution was added to the same beaker. The mixture was then stirred at ambient temperature for 20 minutes until a visually homogeneous formulation solution was obtained. A nicotine succinate formulation was prepared by adding 0.73 g of succinic acid to a beaker, followed by adding 0.5 g of nicotine and 8.77 g of PG / VG (3:7) solution to the same beaker, and then stirring the mixture at 90°C for 60 minutes until a visually homogeneous formulation solution was obtained, free of undissolved chemicals. A nicotine salicylate formulation was made by adding 0.43 g of salicylic acid to a beaker, followed by 0.5 g of nicotine and 9.07 g of a PG / VG (3:7) solution to the same beaker. The mixture was then stirred at 90°C for 60 minutes until a visually homogenous formulation solution was obtained, free of undissolved chemicals. A nicotine salicylate formulation can also be made by adding 0.43 g of salicylic acid to a beaker, followed by 0.5 g of nicotine to the same beaker. The mixture was stirred at 90°C for 60 minutes until the salicylic acid was completely dissolved and an orange oily mixture was formed. The mixture was cooled to ambient conditions or kept at 90°C when 9.07 g of PG / VG (3:7) solution was added. The mixture was then stirred at 90°C until a visually homogeneous formulation solution was obtained, free of undissolved chemicals. A formulation of nicotine free base can be made by adding 0.5 g of nicotine to a beaker followed by adding 9.5 g of PG / VG (3:7) solution to the same beaker, after which the mixture is stirred at ambient temperature for 10 minutes until a visually homogeneous formulation solution is obtained.

[0082] Various formulations containing different nicotine salts can be similarly prepared, or different concentrations of the above nicotine formulations or other nicotine salt formulations can be prepared, as would be known to one of skill in the art upon reading the disclosure herein.

[0083] Various formulations containing two or more nicotine salts can be similarly prepared in a 3:7 propylene glycol (PG) / vegetable glycerin (VG) solution. For example, 0.43 g (2.5% w / w nicotine) of nicotine levulinate salt and 0.34 g (2.5% w / w nicotine) of nicotine acetate salt are added to 9.23 g of PG / VG solution to obtain a 5% w / w nicotine formulation.

[0084] Further, another exemplary formulation is provided, for example, 0.23 g (1.33% w / w nicotine) of nicotine benzoate salt (1:1 molar ratio of nicotine / benzoic acid), 0.25 g (1.33% w / w nicotine) of nicotine salicylate salt (1:1 molar ratio of nicotine / salicylic acid), and 0.28 g (1.34% w / w nicotine) of nicotine pyruvate salt (1:1 molar ratio of nicotine / pyruvic acid) were added to 9.25 g of PG / VG solution to obtain a 5% w / w nicotine formulation.

[0085] Example 2: Study of the pulse rate of nicotine solution delivered via e-cigarette Representative formulations of nicotine levulinate, nicotine benzoate, nicotine succinate, nicotine salicylate, nicotine malate, nicotine pyruvate, nicotine citrate, nicotine free base, and a propylene glycol control were prepared in 3% w / w solutions as described in Example 1 and administered to the same human subjects via electronic cigarette in the same manner. Approximately 0.5 mL of each solution was loaded into an "eRoll" cartridge atomizer (joyetech.com) for use in the study. The atomizer was then inserted into an "eRoll" electronic cigarette (same manufacturer). The operating temperature ranged from about 150°C to about 250°C, or alternatively, from about 180°C to about 220°C.

[0086] Heart rate was measured for 6 minutes; starting 1 minute before the start of the puff, continuing for 3 minutes during the puff, and continuing until 2 minutes after the end of the puff. Participants took 10 puffs over 3 minutes on each occasion. Baseline heart rate was the average heart rate over the first minute before the start of the puff. Post-puff heart rate was averaged over a 20-second interval. Puffs (inhalations) occurred every 20 seconds for a total of 3 minutes. Normalized heart rate was determined as the ratio of each heart rate data point to the base heart rate. The final results are shown as normalized heart rate, as shown in the first 4 minutes in Figure 1.

[0087] Figure 1 summarizes the results from heart rate measurements obtained for various nicotine salt formulations. For ease of reference in Figure 1, the nicotine formulations from top to bottom (highest to lowest normalized heart rate) at 180 seconds are as follows: nicotine salicylate, nicotine malate, nicotine levulinate (almost identical to nicotine malate at 180 seconds, hence the second reference point: the nicotine malate curve is lower than the nicotine levulinate curve at 160 seconds), nicotine pyruvate, nicotine benzoate, nicotine citrate, nicotine succinate, and nicotine free base. The bottom curve (lowest normalized heart rate) at 180 seconds is associated with placebo (100% propylene glycol). Test formulations containing nicotine salts increase heart rate significantly faster than placebo. Test formulations containing nicotine salts also induced faster and more significant increases compared to nicotine free base formulations of equivalent weight. Additionally, nicotine salts (e.g., nicotine benzoate and nicotine pyruvate) prepared from acids with calculated vapor pressures of 20-200 mmHg at 200°C (with the exception of benzoic acid (171.66 mmHg) and pyruvic acid (boiling points of 165°C)), induced faster increases in heart rate than the others. Nicotine salts (e.g., nicotine levulinate, nicotine benzoate, and nicotine salicylate) prepared from acids (benzoic acid, levulinic acid, and salicylic acid, respectively) induced more significant increases in heart rate. Therefore, other suitable nicotine salts formed from acids with similar vapor pressures and / or similar boiling points may be used in accordance with the methods of the present invention. Experiences of increases in heart rate theoretically close to or equivalent to those experienced with conventional burned cigarettes have not been demonstrated or identified in e-cigarette devices. Even when nicotine salts were used as additives to tobacco (nicotine salt solutions of 20% (w / w) or more), it was not demonstrated or identified in low-temperature tobacco vaporizers (e-cigarettes), which do not burn tobacco. Therefore, the results from this experiment were surprising and unexpected.

[0088] Example 3: Satisfaction Study of Nicotine Salt Solutions Delivered via E-Cigarette In addition to the heart rate study described in Example 2, nicotine formulations (using a 3% w / w nicotine formulation as described in Example 1) were used to conduct a satisfaction study in one test participant. Test participants, i.e., e-cigarette and / or traditional cigarette users, were required to abstain from nicotine for at least 12 hours prior to the test. In each case, participants took 10 puffs over 3 minutes using an e-cigarette (the same as used in Example 2), after which they were asked to rate their perceived level of physical and emotional satisfaction (on a 0-10 scale, with 0 being no physical or emotional satisfaction). Results indicated that nicotine free base was the least satisfying compound. Nicotine benzoate, nicotine salicylate, and nicotine succinate all performed well, followed by nicotine pyruvate, nicotine citrate, and nicotine pyruvate salt.

[0089] Based on satisfaction studies, nicotine salt formulations with acids having a vapor pressure range of >20 mmHg at 200°C, or 20-200 mmHg at 200°C, or between 100-300 mmHg at 200°C, provide more satisfaction than the rest (except pyruvic acid, which has a boiling point of 165°C). For reference, salicylic acid has a vapor pressure of approximately 135.7 mmHg at 200°C, benzoic acid has a vapor pressure of approximately 171.7 mmHg at 200°C, lauric acid has a vapor pressure of approximately 38 mmHg at 200°C, and levulinic acid has a vapor pressure of approximately 149 mmHg at 200°C.

[0090] Example 4: Test Formulation 1 (TF1): A nicotine levulinate solution in glycerin containing nicotine salt was prepared using the following: 1.26 g 1:3 nicotine levulinate (87.4% w / w), 8.74 g (87.4% w / w) glycerol - 10.0 g total.

[0091] Pure nicotine levulinate was added to glycerin and mixed thoroughly. L-nicotine has a molar mass of 162.2 g, and the molar mass of levulinic acid is 1161 g. At a 1:3 molar ratio, the weight percent of nicotine in nicotine levulinate is obtained as follows: 162.2 g / (162.2 g + (3 x 116.1 g)) = 31.8% (w / w).

[0092] Example 5: Test Formulation 2 (TF2): A solution of free base nicotine in glycerol containing 0.40 g (4.00% w / w) of L-nicotine was dissolved in 9.60 g (96.0% w / w) of glycerol and mixed thoroughly.

[0093] Example 6: Heart rate study upon administration of nicotine solution via electronic cigarette Both formulations (TF1 and TF2) were administered to the same human subjects in the same manner via electronic cigarette: 0.6 ml of each solution was loaded into an "eGo-C" cartridge atomizer (joyetech.com). The atomizer was then attached to an "eVic" electronic cigarette (same manufacturer). This model of electronic cigarette allows for adjustable voltage and wattage via the atomizer. The operating temperature of the electronic cigarette was from about 150°C to about 250°C, or from about 180°C to about 220°C.

[0094] In both cases, the atomizer had a resistance of 2.4 ohms and the e-cigarette was set to 4.24V, resulting in a power output of 7.49W (P=V^2 / R).

[0095] Heart rate was measured at 30-second intervals for 10 minutes from the start of the puff. Participants took 10 puffs for 3 minutes in each case. Solid line (second highest peak): cigarette; dark dotted line (highest peak): test formulation 1 (TF1 - nicotine salt formulation); light dotted line: test formulation 2 (TF2 - nicotine formulation). A comparison between cigarettes, TF1, and TF2 is shown in Figure 2.

[0096] Figure 2 clearly shows that the test formulation containing nicotine levulinate (TF1) produces a faster increase in heart rate than nicotine alone (TF2). Furthermore, TF1 exhibits a rate of increase very similar to that observed with tobacco. Other salts have been tested and found to increase heart rate compared to pure nicotine solution. Therefore, other suitable nicotine salts that produce similar effects may be used in accordance with the methods of the present invention, such as other keto acids (alpha-keto acids, beta-keto acids, gamma-keto acids, etc.), such as pyruvate, oxaloacetate, and acetoacetate. This heart rate increase experience, comparable to that observed with conventional combusted cigarettes, has not been demonstrated or identified in other e-cigarette devices, even when nicotine salts are used as tobacco additives (nicotine salt solutions of 20% (w / w) or more), and it has not been demonstrated or identified in low-temperature tobacco vaporization devices (e-cigarettes) that do not combust tobacco. Therefore, the results from this experiment were surprising and unexpected.

[0097] Furthermore, the data appear to correlate well with previous results shown in Figure 2.

[0098] As previously noted in the satisfaction studies, nicotine salt formulations with acids having a pressure between 20-300 mmHg at 200°C provide more satisfaction than the others, with the exception of nicotine salt formulations made with pyruvic acid, which has a boiling point of 165°C, as noted in Figure 3. Based on the results herein, these nicotine salt formulations are expected to have either: Vapor pressure of 20-300mmHg at -200℃ Vapor pressure >20mmHg at -200°C, - a difference of at least 50 °C between the boiling point and the melting point, - A boiling point above 160°C and a melting point below 160°C; - a difference of at least 50 °C between the boiling point and the melting point, - A boiling point higher than 160°C and a melting point lower than 160°C, with a difference of at least 50°C between the boiling point and the melting point; - Boiling point no more than 40°C lower than the operating temperature, and a boiling point at least 40°C below the operating temperature, The combination results in one or more of the following effects:

[0099] T max Time to Peak Blood Concentration: Based on the results established herein, users of e-cigarettes containing nicotine salt formulations experience comparable rates of physical and emotional satisfaction with formulations containing a mixture of nicotine salts prepared with an appropriate acid at least 1.2 to 3 times faster than users of formulations containing freebase nicotine. As shown in Figure 1, nicotine from nicotine salt formulations appears to produce pulses at nearly 1.2 times an individual's normal heart rate approximately 40 seconds after the start of a puff, while nicotine from nicotine freebase formulations appears to produce pulses at nearly 1.2 times an individual's normal heart rate approximately 110 seconds after the start of a puff, a 2.75-fold difference in the time to achieve comparable initial satisfaction.

[0100] This is also inconsistent with the data in Figure 2, which show that at approximately 120 seconds (2 minutes), the heart rate of study participants reached a maximum of 105-110 bpm with either regular cigarettes or the nicotine salt formulation (TF1), whereas the same participants' heart rate only reached a maximum of approximately 86 bpm with the nicotine free base formulation (TF2) at approximately 7 minutes; furthermore, the difference in the effect of nicotine salt (and regular cigarettes) relative to free base nicotine was 1.2-fold.

[0101] Furthermore, when considering the peak level of satisfaction (achieved approximately 120 seconds from the start of the puff (time=0)) and looking at the slope of the normalized heart rate line, the approximate slope for those nicotine salt formulations over the range of free base nicotine formulations is between 0.0054 hrn / sec and 0.0025 hrn / sec. By comparison, the slope of the line for free base nicotine formulations is approximately 0.002. This indicates that the available concentration of nicotine is delivered to the user at a rate 1.25 to 2.7 times faster than the free base formulation.

[0102] Another measure of performance;C max - At maximum blood nicotine concentration, similar rates of rise are expected to be measured in blood nicotine concentration, as shown above. That is, the C between regular cigarettes and specific nicotine salt formulations max is comparable, but the free base nicotine solution has a lower C max was predicted based on the results herein and was unexpected based on previously known technology.

[0103] Similarly, certain nicotine salt formulations are predicted based on the results herein, and unexpected based on previously known technology, to have high rates of nicotine blood uptake levels in the early period. Indeed, Example 8 presents data for a number of salt formulations that are consistent with these predictions, made based on the results and testing described herein, and which are unexpected compared to previously available technology.

[0104] Example 7: Study of the pulse rate of nicotine solution delivered via electronic cigarette Representative formulations of nicotine levulinate, nicotine benzoate, nicotine succinate, nicotine salicylate, nicotine malate, nicotine pyruvate, nicotine citrate, nicotine sorbate, nicotine laurate, nicotine free base, and a propylene glycol control were prepared as described in Example 1 and administered to the same human subjects via electronic cigarette in the same manner. Approximately 0.5 mL of each solution was loaded into an "eRoll" cartridge atomizer (joyetech.com) for use in the study. The atomizer was then inserted into an "eRoll" electronic cigarette (same manufacturer). The operating temperature ranged from about 150°C to about 250°C or from about 180°C to about 220°C.

[0105] Heart rate was measured for 6 minutes: 1 minute before the start of the puff, 3 minutes during the puff, and continuously until 2 minutes after the end of the puff. Participants took 10 puffs for 3 minutes each time. The base heart rate was the average heart rate over the first minute before the start of the puff. Heart rates after the start of the puff were averaged over a 20-second interval. The normalized heart rate was defined as the ratio of each heart rate data point to the base heart rate. The final result was expressed as the normalized heart rate.

[0106] Example 8: Plasma testing Plasma testing was performed on three subjects (n=3). Eight test articles were used in this study: one reference cigarette and seven blends used in e-cigarette devices with operating temperatures of about 150°C to about 250°C or about 180°C to about 220°C. The reference cigarette was Pall Mall (New Zealand). Seven blends were tested in e-cigarettes: 2% free base, 2% benzoic acid, 4% benzoic acid, 2% citric acid, 2% malic acid, 2% salicylic acid, and 2% succinic acid. With the exception of 2% succinic acid (n=1), all other blends had an n=3. The seven blends were liquid formulations prepared as described in Example 1.

[0107] The nicotine concentration in each formulation was confirmed using a UV spectrophotometer (Agilent Cary 60). Sample solutions for UV analysis were made by dissolving 20 mg of each formulation in 20 mL of 0.3% aqueous HCl. The sample solutions were then scanned on the UV spectrophotometer, and the characteristic nicotine peak at 259 nm was used to quantify the nicotine in the sample relative to a standard solution of 19.8 μg / mL nicotine in the same diluent. The standard solution was prepared by first dissolving 19.8 mg nicotine in 10 mL of 0.3% aqueous HCl, followed by a 1:100 dilution with 0.3% aqueous HCl. The reported nicotine concentrations for all formulations were within 95%-105% of the claimed concentrations.

[0108] All subjects were able to consume 30-55 mg of a liquid formulation of each tested compound using an e-cigarette.

[0109] Literature results: C. Bullen et al., Tobacco Control 2010, 19:98-103 Cigarettes (5 min ad lib, n=9): T max =14.3(8.8-19.9),C max = 13.4 (6.5-20.3) 1.4% E-cig (5 min ad lib, n = 8): T max =19.6(4.9-34.2),C max =1.3(0.0-2.6)Nicorette inhaler(20mg / 20min,n=10):T max =32.0(18.7-45.3),C max =2.1(1.0-3.1)

[0110] 2% Nicotine Blend C max Estimated value: C max =Consumption*Intensity*Bioavailability / (Volume of distribution*Body weight)=40mg*2%*80% / (2.6L / kg*75kg)=3.3ng / mL

[0111] 4% Nicotine Blend C max Estimated value: C max =Consumption*Intensity*Bioavailability / (Volume of distribution*Body weight)=40mg*4%*80% / (2.6L / kg*75kg)=6.6ng / mL

[0112] The pharmacokinetic profile of the plasma study is shown in Figure 4, which shows the blood nicotine concentration (ng / ml) over time after the first puff (inhalation) of aerosol from PallMall smoke or e-cigarette. Ten puffs were taken at 30-second intervals, starting at time = 0 and continuing for 4.5 minutes. For ease of reference and discussion of Figure 4, the curves on the graph from top to bottom (highest mean blood nicotine concentration to lowest mean blood nicotine concentration) at the 5-minute time point were a composite of 4% benzoic acid, 2% succinic acid, 2% salicylic acid, 2% citric acid, PallMall cigarette, 2% benzoic acid, 2% malic acid, and 2% free base. While listed from highest to lowest at this point, this does not imply that there are statistically significant differences between any of the salt formulations or between any of the salt formulations and PallMall. However, the C of a particular salt formulation may be significantly different. max Based on the data presented in Figure 4 and other studies herein, the free base formulation appears to be lower than the others tested at some time points, suggesting that there may be statistically significant differences between the two. max The results appear to be statistically different from the salt formulations and / or PallMall with respect to C. Those skilled in the art, with reference to this disclosure, will be able to appropriately enhance their testing to determine the actual statistical differences between one or more formulations and cigarettes, or between formulations in e-cigarettes, as appropriate herein. For ease of reference and discussion, Tables 1 and 2 show the detected nicotine levels (averaged across all users) for each formulation and PallMall, which are shown in Tables 1 and 2. max and T max and AUC, in ng / mL. Therefore, the data from these tables, along with the raw data, were used to generate Figures 4, 5, and 6.

[0113] [Table 1]

[0114] [Table 2]

[0115] Seven compounds and the reference cigarette T max and C max A comparison of the C of the seven blends and the reference cigarette is shown in Figure 5. max Comparisons of AUC and TC are shown in Figure 6. Due to the time constraints of the washout period, baseline blood nicotine concentrations (T = -2 and t = 0 min) were higher for samples consumed later on the test day. The data in Figures 4-6 show corrected blood nicotine concentration values (i.e., apparent blood nicotine concentrations at each time point minus baseline nicotine concentrations for the same samples).

[0116] The rate of nicotine uptake into the user's blood for each sample within the first 90 seconds is shown in Table 3.

[0117] [Table 3]

[0118] T max and C max While the values of .DELTA. were comparable between the tested blends and the reference cigarette (except for the 2% free base blend), the nicotine absorption rates within the first 90 seconds varied among the test products. In particular, four blends (2% salicylic acid, 2% benzoic acid, 4% benzoic acid, and 2% citric acid) exhibited significantly higher absorption rates within the first 90 seconds compared to the other blends and the reference cigarette. These four blends contain salts (salicylic acid, benzoic acid, and citric acid) that performed well in the satisfaction study of Example 3. Furthermore, the 2% benzoic acid and 4% benzoic acid blends had comparable absorption rates, suggesting that lower nicotine salt concentrations do not adversely affect absorption rates.

[0119] Example 9: Plasma studies Plasma testing will be conducted on 24 subjects (N=24). Eight test articles will be used in this study: one reference cigarette and seven blends delivered to users via e-cigarette as an aerosol. The operating temperature of the e-cigarette will be from about 150°C to about 250°C, or from about 180°C to about 220°C. The reference cigarette will be Pall Mall (New Zealand). Seven blends will be tested: 2% free base, 2% benzoic acid, 4% benzoic acid, 2% citric acid, 2% malic acid, 2% salicylic acid, and 2% succinic acid. The seven blends are liquid formulations prepared according to a protocol similar to that described in Example 1 below.

[0120] All subjects consume 30-55 mg of a liquid formulation of each compound tested. Ten puffs are taken at 30-second intervals, starting at time = 0 and continuing for 4.5 minutes. Plasma testing is performed for at least 60 minutes after the first puff (t = 0). Pharmacokinetic data (e.g., C) on nicotine in the user's plasma are collected. max , T max , AUC) are obtained at various time points during these 60 minutes, along with the rate of nicotine absorption within the first 90 seconds for each test article.

[0121] Example 10: Plasma studies Plasma testing will be conducted on 24 subjects (N=24). Eleven test articles will be used in this study: one reference cigarette and ten blends delivered to users via e-cigarette as an aerosol. The reference cigarette is Pall Mall (New Zealand). The operating temperature of the e-cigarette is from about 150°C to about 250°C, or from about 180°C to about 220°C. Seven blends will be tested: 2% free base, 2% benzoic acid, 2% sorbic acid, 2% pyruvate, 2% lauric acid, 2% levulinic acid, 2% citric acid, 2% malic acid, 2% salicylic acid, and 2% succinic acid. The ten blends are liquid formulations prepared according to a protocol similar to that described in Example 1 below.

[0122] All subjects consume 30-55 mg of a liquid formulation of each compound tested. Ten puffs are taken at 30-second intervals, starting at time = 0 and continuing for 4.5 minutes. Plasma testing is performed for at least 60 minutes after the first puff (t = 0). Pharmacokinetic data (e.g., C) on nicotine in the user's plasma are collected. max , T max , AUC) are obtained at various time points during these 60 minutes, along with the rate of nicotine absorption within the first 90 seconds for each test article.

[0123] Example 11: Plasma studies Plasma studies are conducted on 24 subjects (N=24). 21 test articles are used in this study: one reference cigarette and 20 composites delivered to users via e-cigarette as aerosol. The reference cigarette is Pall Mall (New Zealand). The operating temperature of e-cigarettes is from about 150°C to about 250°C, or from about 180°C to about 220°C. 20 composites were tested: 2% free base, 4% free base, 2% benzoic acid, 4% benzoic acid, 2% sorbic acid, 4% sorbic acid, 2% pyruvic acid, 4% pyruvate, 2% lauric acid, 4% lauric acid, 2% levulinic acid, 4 levulinic acid, 2% citric acid, 4% citric acid, 2% malic acid, 4% malic acid, 2% salicylic acid, 4% salicylic acid, 2% succinic acid, and 4% succinic acid. The 20 blends are liquid formulations prepared according to a protocol similar to that described in Example 1 below.

[0124] All subjects consume 30-55 mg of a liquid formulation of each compound tested. Ten puffs are taken at 30-second intervals, starting at time = 0 and continuing for 4.5 minutes. Plasma testing is performed for at least 60 minutes after the first puff (t = 0). Pharmacokinetic data (e.g., C) on nicotine in the user's plasma are collected. max , T max , AUC) are obtained at various time points during these 60 minutes, along with the rate of nicotine absorption within the first 90 seconds for each test article.

[0125] Example 12: Plasma studies Plasma studies are conducted on 24 subjects (N=24). 21 test articles are used in this study: one reference cigarette and 20 composites delivered to users via e-cigarette as aerosol. The reference cigarette is Pall Mall (New Zealand). The operating temperature of e-cigarettes is from about 150°C to about 250°C or from about 180°C to about 220°C. 20 composites were tested: 2% free base, 1% free base, 2% benzoic acid, 1% benzoic acid, 2% sorbic acid, 1% sorbic acid, 2% pyruvic acid, 1% pyruvate, 2% lauric acid, 1% lauric acid, 2% levulinic acid, 1% levulinic acid, 2% citric acid, 1% citric acid, 2% malic acid, 1% malic acid, 2% salicylic acid, 1% salicylic acid, 2% succinic acid, and 1% succinic acid. The 20 blends are liquid formulations prepared according to a protocol similar to that described in Example 1 below.

[0126] All subjects consume 30-55 mg of a liquid formulation of each compound tested. Ten puffs are taken at 30-second intervals, starting at time = 0 and continuing for 4.5 minutes. Plasma testing is performed for at least 60 minutes after the first puff (t = 0). Pharmacokinetic data (e.g., C) on nicotine in the user's plasma are collected. max , T max , AUC) are obtained at various time points during these 60 minutes, along with the rate of nicotine absorption within the first 90 seconds for each test article.

[0127] Further understanding may be gained by considering the following numbered embodiments. 1. A method of delivering nicotine to a user, the method comprising the steps of: having the user activate an electronic cigarette, wherein the electronic cigarette contains a nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is characterized by a vapor pressure of greater than 20 mmHg at 200°C; and inhaling an aerosol produced from the nicotine salt formulation heated by the electronic cigarette. 2. A method of delivering nicotine to a user, the method comprising: having the user activate an electronic cigarette, wherein the electronic cigarette contains a nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is characterized by a vapor pressure of about 20 to 200 mmHg at 200°C; and inhaling an aerosol produced from the nicotine salt formulation heated by the electronic cigarette. 3. A method of delivering nicotine to a user, the method comprising: activating an electronic cigarette, wherein the electronic cigarette contains a nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein an acid used to form the nicotine salt is further characterized by a melting point below 160°C, a boiling point above 160°C, and a difference between the melting point and the boiling point of at least 50 degrees; and inhaling an aerosol produced from the nicotine salt formulation heated by the electronic cigarette. 4. A method of delivering nicotine to a user, the method comprising: providing an electronic cigarette to a user, the electronic cigarette comprising a nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein an acid used to form the nicotine salt is further characterized by a melting point at least 40 degrees below the operating temperature of the electronic cigarette, a boiling point no more than 40 degrees below the operating temperature of the electronic cigarette, and a difference between the melting point and the boiling point of at least 50 degrees; and inhaling an aerosol produced from the nicotine salt formulation heated by the electronic cigarette. 5. The method according to any one of embodiments 1-3, wherein the operating temperature is from 150°C to 250°C. 6. The method according to any one of embodiments 1-3, wherein the operating temperature is from 180°C to 220°C. 7. The method according to any one of embodiments 1-3, wherein the operating temperature is about 200°C. 8. The method according to embodiment 4 is characterized in that the operating temperature is from 150°C to 250°C. 9. The method according to embodiment 4, wherein the operating temperature is from 180°C to 220°C. 10. The method of embodiment 4 is characterized in that the operating temperature is about 200°C. 11. The method according to any one of embodiments 1-10, wherein the aerosol comprises a condensate of a nicotine salt. 12. The method according to any one of embodiments 1-10, wherein the aerosol comprises a condensate of free base nicotine. 13. The method according to any one of embodiments 1-10, wherein the aerosol comprises a condensate of free base nicotine and a condensate of a carrier. 14. The method according to any one of embodiments 1-10, wherein the aerosol comprises a condensate of free base nicotine and a condensate of an acid. 15. The method of any one of embodiments 1-14, wherein the aerosol comprises condensate having a particle size of about 0.1 microns to about 5 microns. 16. The method of any one of embodiments 1-14, wherein the aerosol comprises condensate having a particle size of about 0.1 microns to about 1 or 2 microns. 17. The method of any one of embodiments 1-14, wherein the aerosol comprises condensate having a particle size of about 0.1 microns to about 0.7 microns. 18. The method of any one of embodiments 1-14, wherein the aerosol comprises condensate having a particle size of about 0.3 microns to about 0.4 microns. 19. The method according to any one of embodiments 1-18, wherein the acid is a carboxylic acid. 20. The method according to any one of embodiments 1-18, wherein the acid used to form the nicotine salt is an organic acid. 21. The method according to embodiment 20, wherein the organic acid is a monocarboxylic acid, an aromatic acid, or a keto acid. 22. The method of embodiment 20, wherein the organic acid is formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, capric acid, citric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, phenylacetic acid, benzoic acid, pyruvic acid, levulinic acid, tartaric acid, lactic acid, malonic acid, succinic acid, fumaric acid, finnaric acid, gluconic acid, saccharic acid, salicylic acid, sorbic acid, malonic acid, or malic acid. 23. The method according to any one of embodiments 1-18, wherein the acid used to form the nicotine salt is salicylic acid. 24. The method according to any one of embodiments 1-18, wherein the acid used to form the nicotine salt is benzoic acid. 25. The method according to any one of embodiments 1-18, wherein the acid used to form the nicotine salt is pyruvic acid. 26. The method according to any one of embodiments 1-18, wherein the acid used to form the nicotine salt is sorbic acid. 27. The method according to any one of embodiments 1-18, wherein the acid used to form the nicotine salt is lauric acid. 28. The method according to any one of embodiments 1-18, wherein the acid used to form the nicotine salt is levulinic acid. 29. The method according to any one of embodiments 1-18, wherein the nicotine salt comprises nicotine pyruvate. 30. The method according to any one of embodiments 1-18, wherein the nicotine salt comprises nicotine salicylate. 31. The method according to any one of embodiments 1-18, wherein the nicotine salt comprises nicotine sorbate. 32. The method according to any one of embodiments 1-18, wherein the nicotine salt comprises nicotine laurate. 33. The method according to any one of embodiments 1-18, wherein the nicotine salt comprises nicotine levulinate. 34. The method according to any one of embodiments 1-18, wherein the nicotine salt comprises nicotine benzoate. 35. The method of any one of embodiments 1-34, wherein the liquid carrier comprises glycerol, propylene glycol, trimethylene glycol, water, ethanol, or a combination thereof. 36. The method of any one of embodiments 1-34, wherein the liquid carrier comprises propylene glycol and vegetable glycerin. 37. The method of any one of embodiments 1-34, wherein the liquid carrier comprises 20% to 50% propylene glycol and 80% to 50% vegetable glycerin. 38. The method of any one of embodiments 1-34, wherein the liquid carrier comprises 30% propylene glycol and 70% vegetable glycerin. 39. The method of any one of embodiments 1-38, wherein the nicotine salt is in an amount to form about 0.5% to about 20% nicotine in the inhalable aerosol. 40. The method of any one of embodiments 1-38, wherein the nicotine salt is in an amount to form about 1% to about 20% of the nicotine in the inhalable aerosol. 41. The method according to any one of embodiments 1-40, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 25% (w / w). 42. The method according to any one of embodiments 1-40, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 20% (w / w). 43. The method according to any one of embodiments 1-40, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 18% (w / w). 44. The method according to any one of embodiments 1-40, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 15% (w / w). 45. The method according to any one of embodiments 1-40, wherein the liquid formulation has a nicotine concentration of about 4% (w / w) to about 12% (w / w). 46. The method according to any one of embodiments 1-40, wherein the liquid formulation has a nicotine concentration of about 4% (w / w). 47. The method according to any one of embodiments 1-40, wherein the liquid formulation has a nicotine concentration of about 2% (w / w). 48. The method according to any one of embodiments 1-47, wherein the formulation further comprises a flavorant. 49. The method according to any one of embodiments 1-48, wherein the formulation is non-corrosive to electronic cigarettes. 50. The method of any one of embodiments 1-49, wherein the acid is stable at or below the operating temperature or about 200°C. 51. The method of any one of embodiments 1-50, wherein the acid does not decompose at or below the operating temperature or about 200°C. 52. The method of any one of embodiments 1-51, wherein the acid does not oxidize at or below the operating temperature or about 200°C. 53. The method according to any one of embodiments 1-52, wherein the formulation is non-corrosive to electronic cigarettes. 54. The method according to any one of embodiments 1-53, wherein the formulation is non-toxic to users of electronic cigarettes. 55. The method according to any one of embodiments 1-54, wherein the formulation further comprises one or more additional nicotine salts in a biologically acceptable liquid carrier suitable for generating an inhalable aerosol upon heating. 56. The method of embodiment 55, wherein the second acid used to form the additional nicotine salt is selected from the group consisting of salicylic acid, sorbic acid, benzoic acid, pyruvic acid, lauric acid, and levulinic acid. 57. A method for delivering nicotine to a user's blood, the method comprising providing an aerosol to be inhaled by a user from an electronic cigarette comprising a nicotine salt formulation, the aerosol providing comprising the electronic cigarette heating the formulation, thereby generating the aerosol, the aerosol effective to deliver a nicotine level in the user's blood that is at least 5 ng / mL for about 1.5 minutes after the first of 10 puffs of the aerosol, each puff being spaced 30 seconds apart. 58. The method of embodiment 54, wherein the nicotine salt formulation comprises a nicotine salt in a biologically acceptable liquid carrier, and the acid used to form the nicotine salt is characterized by a vapor pressure of greater than 20 mmHg at 200°C. 59. The method of embodiment 54, wherein the nicotine salt formulation comprises a nicotine salt in a biologically acceptable liquid carrier, and the acid used to form the nicotine salt is characterized by a vapor pressure of about 20 to 200 mmHg at 200°C. 60. The method of embodiment 54, wherein the nicotine salt formulation comprises a nicotine salt in a biologically acceptable liquid carrier, and wherein the acid used to form the nicotine salt is further characterized by a melting point below 160°C, a boiling point above 160°C, and a difference of at least 50 degrees between the melting point and the boiling point. 61. The method according to any one of embodiments 57-60, wherein the heating of the formulation is at a temperature of from 150°C to 250°C. 62. The method according to any one of embodiments 57-60, wherein the heating of the formulation is at a temperature of from 180°C to 220°C. 63. The method according to any one of embodiments 57-60, wherein the heating of the formulation is at a temperature of about 200°C. 64. The method of embodiment 54, wherein the nicotine salt formulation comprises a nicotine salt in a biologically acceptable liquid carrier, and wherein the acid used to form the nicotine salt is further characterized by a melting point at least 40 degrees below the operating temperature of the electronic cigarette, a boiling point that is no more than 40 degrees below the operating temperature of the electronic cigarette, and a difference of at least 50 degrees between the melting point and the boiling point, and wherein the operating temperature is 200°C. 65. The method according to any one of embodiments 57-64, further comprising: max is characterized by an average of more than 10 ng / mL. 66. The method according to any one of embodiments 57-64, further comprising: max is characterized by an average blood glucose level exceeding 11 ng / mL. 67. The method according to any one of embodiments 57-64, further comprising: max is characterized by an average of between 10 ng / mL and 16 ng / mL. 68. The method according to any one of embodiments 57-64, further comprising: max is characterized by an average of between 11 ng / mL and 15 ng / mL. 69. The method according to any one of embodiments 57-64, further comprising: max is characterized by an average of between 11 ng / mL and 14 ng / mL. 70. The method according to any one of embodiments 57-69, further comprising: max is characterized by an average of less than 10 minutes. 71. The method according to any one of embodiments 57-69, further comprising: max is characterized by an average of less than 9 minutes. 72. The method according to any one of embodiments 57-69, further comprising: max is characterized by an average of less than 8 minutes. 73. The method according to any one of embodiments 57-69, further comprising: max is characterized by an average of less than 7 minutes. 74. The method according to any one of embodiments 54-63, further comprising: max is characterized by an average of 3 to 10 minutes. 75. The method according to any one of embodiments 57-69, further comprising:max is characterized by an average of 3 to 7.5 minutes. 76. The method according to any one of embodiments 57-75, wherein the aerosol comprises a condensate of a nicotine salt. 77. The method according to any one of embodiments 57-75, wherein the aerosol comprises a condensate of free base nicotine. 78. The method according to any one of embodiments 57-75, wherein the aerosol comprises a condensate of free base nicotine and a condensate of a carrier. 79. The method according to any one of embodiments 57-75, wherein the aerosol comprises a condensate of free base nicotine and a condensate of an acid. 80. The method of any one of embodiments 57-79, wherein the aerosol comprises condensate having a particle size of about 0.1 microns to about 5 microns. 81. The method of any one of embodiments 57-79, wherein the aerosol comprises condensate having a particle size of about 0.1 microns to about 1 or 2 microns. 82. The method of any one of embodiments 57-79, wherein the aerosol comprises condensate having a particle size of about 0.1 microns to about 0.7 microns. 83. The method of any one of embodiments 57-79, wherein the aerosol comprises condensate having a particle size of about 0.3 microns to about 0.4 microns. 84. The method according to any one of embodiments 57-83, wherein the acid is a carboxylic acid. 85. The method according to any one of embodiments 57-83, wherein the acid used to form the nicotine salt is an organic acid. 86. The method according to embodiment 85, wherein the organic acid is a monocarboxylic acid, an aromatic acid, or a keto acid. 87. The method according to embodiment 85, wherein the organic acid is formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, capric acid, citric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, phenylacetic acid, benzoic acid, pyruvic acid, levulinic acid, tartaric acid, lactic acid, malonic acid, succinic acid, fumaric acid, finic acid, gluconic acid, saccharic acid, salicylic acid, sorbic acid, malonic acid, or malic acid. 88. The method according to any one of embodiments 57-83, wherein the acid used to form the nicotine salt is salicylic acid. 89. The method according to any one of embodiments 57-83, wherein the acid used to form the nicotine salt is benzoic acid. 90. The method according to any one of embodiments 57-83, wherein the acid used to form the nicotine salt is pyruvic acid. 91. The method according to any one of embodiments 57-83, wherein the acid used to form the nicotine salt is sorbic acid. 92. The method according to any one of embodiments 57-83, wherein the acid used to form the nicotine salt is lauric acid. 93. The method according to any one of embodiments 57-83, wherein the acid used to form the nicotine salt is levulinic acid. 94. The method according to any one of embodiments 57-83, wherein the nicotine salt comprises nicotine pyruvate. 95. The method according to any one of embodiments 57-83, wherein the nicotine salt comprises nicotine salicylate. 96. The method according to any one of embodiments 57-83, wherein the nicotine salt comprises nicotine sorbate. 97. The method according to any one of embodiments 57-83, wherein the nicotine salt comprises nicotine laurate. 98. The method according to any one of embodiments 57-83, wherein the nicotine salt comprises nicotine levulinate. 99. The method according to any one of embodiments 57-83, wherein the nicotine salt comprises nicotine benzoate. 100. The method according to any one of embodiments 57-99, wherein the liquid carrier comprises glycerol, propylene glycol, trimethylene glycol, water, ethanol, or a combination thereof. 101. The method according to any one of embodiments 57-99, wherein the liquid carrier comprises propylene glycol and vegetable glycerin. 102. The method according to any one of embodiments 57-99, wherein the liquid carrier comprises 20% to 50% of propylene glycol and 80% to 50% of vegetable glycerin. 103. The method according to any one of embodiments 57-99, wherein the liquid carrier comprises 30% propylene glycol and 70% vegetable glycerin. 104. The method of any one of embodiments 57-103, wherein the nicotine salt is in an amount to form about 0.5% to about 20% nicotine in the inhalable aerosol. 105. The method of any one of embodiments 57-103, wherein the nicotine salt is in an amount to form about 1% to about 20% of the nicotine in the inhalable aerosol. 106. The method according to any one of embodiments 57-105, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 25% (w / w). 107. The method according to any one of embodiments 57-105, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 20% (w / w). 108. The method according to any one of embodiments 57-105, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 18% (w / w). 109. The method according to any one of embodiments 57-105, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 15% (w / w). 110. The method according to any one of embodiments 57-105, wherein the liquid formulation has a nicotine concentration of about 4% (w / w) to about 12% (w / w). 111. The method according to any one of embodiments 57-105, wherein the liquid formulation has a nicotine concentration of about 4% (w / w). 112. The method according to any one of embodiments 57-105, wherein the liquid formulation has a nicotine concentration of about 2% (w / w). 113. The method according to any one of embodiments 57-112, wherein the liquid formulation further comprises a flavoring material. 114. The method according to any one of embodiments 57-113, wherein the formulation is non-corrosive to electronic cigarettes. 115. The method of any one of embodiments 57-114, wherein the acid is stable at or below the operating temperature or about 200°C. 116. The method of any one of embodiments 57-115, wherein the acid does not decompose at or below the operating temperature or about 200°C. 117. The method of any one of embodiments 57-116, wherein the acid does not oxidize at or below the operating temperature or about 200°C. 118. The method according to any one of embodiments 57-117, wherein the formulation is non-corrosive to electronic cigarettes. 119. The method according to any one of embodiments 57-118, wherein the formulation is non-toxic to users of electronic cigarettes. 120. The method according to any one of embodiments 57-119, wherein the formulation further comprises one or more additional nicotine salts in a biologically acceptable liquid carrier suitable for generating an inhalable aerosol upon heating. 121. The method of embodiment 120 is characterized in that the second acid used to form the additional nicotine salt is selected from the group consisting of salicylic acid, sorbic acid, benzoic acid, pyruvic acid, lauric acid, and levulinic acid. 122. A nicotine salt liquid formulation in an electronic cigarette for producing an inhalable aerosol upon heating of the electronic cigarette, wherein the formulation in the electronic cigarette comprises a nicotine salt in a biologically acceptable liquid carrier, and wherein the acid used to form the nicotine salt is characterized by a vapor pressure of greater than 20 mmHg at 200°C. 123. A nicotine salt liquid formulation in an electronic cigarette for producing an inhalable aerosol upon heating of the electronic cigarette, wherein the formulation in the electronic cigarette comprises a nicotine salt in a biologically acceptable liquid carrier, and wherein the acid used to form the nicotine salt is characterized by a vapor pressure of about 20 to 200 mmHg at 200°C. 124. A nicotine salt liquid formulation in an electronic cigarette for producing an inhalable aerosol upon heating of the electronic cigarette, wherein the formulation in the electronic cigarette comprises a nicotine salt in a biologically acceptable liquid carrier, and wherein the acid used to form the nicotine salt is further characterized by a melting point below 160°C, a boiling point above 160°C, and a difference of at least 50 degrees between the melting point and the boiling point. 125. A nicotine salt liquid formulation in an electronic cigarette for producing an inhalable aerosol upon heating of the electronic cigarette, wherein the formulation in the electronic cigarette comprises a nicotine salt in a biologically acceptable liquid carrier, and wherein the acid used to form the nicotine salt is further characterized by a melting point at least 40 degrees below the operating temperature of the electronic cigarette, a boiling point that is no more than 40 degrees below the operating temperature of the electronic cigarette, and a difference of at least 50 degrees between the melting point and the boiling point. 126. The nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-124, wherein the electronic cigarette heats the nicotine salt formulation to an operating temperature of 150°C to 250°C. 127. The nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-124, wherein the electronic cigarette heats the nicotine salt formulation to an operating temperature of 180°C to 220°C. 128. The nicotine salt liquid formulation in the electronic cigarette according to any one of embodiments 122-124, wherein the electronic cigarette heats the nicotine salt formulation to an operating temperature of about 200°C. 129. The nicotine salt liquid formulation in the electronic cigarette according to embodiment 125 is characterized in that the operating temperature is from 150°C to 250°C. 130. The nicotine salt liquid formulation in the electronic cigarette according to embodiment 125 is characterized in that the operating temperature is from 180°C to 220°C. 131. The nicotine salt liquid formulation in the electronic cigarette according to embodiment 125 is characterized in that the operating temperature is about 200°C. 132. The nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-131, wherein the acid is a carboxylic acid. 133. The nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-131, characterized in that the acid used to form the nicotine salt is an organic acid. 134. The nicotine salt liquid formulation in an electronic cigarette according to embodiment 133 is characterized in that the organic acid is a monocarboxylic acid, an aromatic acid, or a keto acid. 135. The nicotine salt liquid formulation in an electronic cigarette according to embodiment 133 is characterized in that the organic acid is formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, capric acid, citric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, phenylacetic acid, benzoic acid, pyruvic acid, levulinic acid, tartaric acid, lactic acid, malonic acid, succinic acid, fumaric acid, finic acid, gluconic acid, saccharic acid, salicylic acid, sorbic acid, malonic acid, or malic acid. 136. The nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-131, characterized in that the acid used to form the nicotine salt is salicylic acid. 137. The nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-131, characterized in that the acid used to form the nicotine salt is benzoic acid. 138. The nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-131, wherein the acid used to form the nicotine salt is pyruvic acid. 139. The nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-131, wherein the acid used to form the nicotine salt is sorbic acid. 140. The nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-131, wherein the acid used to form the nicotine salt is lauric acid. 141. The nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-131, characterized in that the acid used to form the nicotine salt is levulinic acid. 142. A nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-131, characterized in that the nicotine salt comprises nicotine pyruvate. 143. The nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-131, characterized in that the nicotine salt comprises nicotine salicylate. 144. The nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-131, characterized in that the nicotine salt comprises nicotine sorbate. 145. The nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-131, characterized in that the nicotine salt comprises nicotine laurate. 146. The nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-131, characterized in that the nicotine salt comprises nicotine levulinate. 147. The nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-131, characterized in that the nicotine salt comprises nicotine benzoate. 148. The nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-147, wherein the liquid carrier comprises glycerol, propylene glycol, trimethylene glycol, water, ethanol, or a combination thereof. 149. A nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-147, characterized in that the liquid carrier comprises propylene glycol and vegetable glycerin. 150. The nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-147, wherein the liquid carrier comprises 20% to 50% of propylene glycol and 80% to 50% of vegetable glycerin. 151. A nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-147, characterized in that the liquid carrier comprises 30% propylene glycol and 70% vegetable glycerin. 152. The nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-151 is characterized in that the nicotine salt is in an amount that forms about 0.5% to about 20% nicotine in the inhalable aerosol. 153. The nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-151, wherein the nicotine salt is in an amount that forms about 1% to about 20% nicotine in the inhalable aerosol. 154. The nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-153, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 25% (w / w). 155. The nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-153, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 20% (w / w). 156. The nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-153, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 18% (w / w). 157. The nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-153, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 15% (w / w). 158. The nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-153, wherein the liquid formulation has a nicotine concentration of about 4% (w / w) to about 12% (w / w). 159. The nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-153, wherein the liquid formulation has a nicotine concentration of about 4% (w / w). 160. The nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-153, wherein the liquid formulation has a nicotine concentration of about 2% (w / w). 161. A nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-160, characterized in that the liquid formulation further comprises a flavoring material. 162. The nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-161, characterized in that the formulation is non-corrosive to the electronic cigarette. 163. The nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-162 is characterized in that the acid is stable at the operating temperature or below about 200°C. 164. The nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-163 is characterized in that the acid does not decompose at the operating temperature or below about 200°C. 165. The nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-164 is characterized in that the acid does not oxidize at or below the operating temperature or about 200°C. 166. The nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-165, characterized in that the formulation is non-corrosive to the electronic cigarette. 167. The nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-166, characterized in that the formulation is non-toxic to the user of the electronic cigarette. 168. The nicotine salt liquid formulation in an electronic cigarette according to any one of embodiments 122-167, characterized in that it further comprises one or more additional nicotine salts in a biologically acceptable liquid carrier suitable for generating an inhalable aerosol upon heating. 169. The nicotine salt liquid formulation in an electronic cigarette according to embodiment 168, wherein the second acid used to form the additional nicotine salt is selected from the group consisting of salicylic acid, sorbic acid, benzoic acid, pyruvic acid, lauric acid, and levulinic acid. 170. A nicotine salt liquid formulation for producing an inhalable aerosol upon heating in an electronic cigarette, the nicotine salt liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier, and characterized in that the acid used to form the nicotine salt is characterized by a vapor pressure of greater than 20 mmHg at 200°C. 171. A nicotine salt liquid formulation for producing an inhalable aerosol upon heating in an electronic cigarette, the nicotine salt liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier, and wherein the acid used to form the nicotine salt is characterized by a vapor pressure of about 20 to 200 mmHg at 200°C. 172. A nicotine salt liquid formulation for producing an inhalable aerosol upon heating in an electronic cigarette, the nicotine salt liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier, characterized in that the acid used to form the nicotine salt is further characterized by a melting point below 160°C, a boiling point above 160°C, and a difference of at least 50 degrees between the melting point and the boiling point. 173. A nicotine salt liquid formulation for producing an inhalable aerosol upon heating in an electronic cigarette, the nicotine salt liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is further characterized by a melting point at least 40 degrees below the operating temperature of the electronic cigarette, a boiling point no more than 40 degrees below the operating temperature of the electronic cigarette, and a difference of at least 50 degrees between the melting point and the boiling point. 174. The nicotine salt liquid formulation of any one of embodiments 170-172, wherein the electronic cigarette heats the nicotine salt formulation to an operating temperature of 150°C to 250°C. 175. The nicotine salt liquid formulation of any one of embodiments 170-172, wherein the electronic cigarette heats the nicotine salt formulation to an operating temperature of 180°C to 220°C. 176. The nicotine salt liquid formulation of any one of embodiments 170-172, wherein the electronic cigarette heats the nicotine salt formulation to an operating temperature of about 200°C. 177. The nicotine salt liquid formulation according to embodiment 173 is characterized in that the operating temperature is from 150°C to 250°C. 178. The nicotine salt liquid formulation according to embodiment 173 is characterized in that the operating temperature is from 180°C to 220°C. 179. The nicotine salt liquid formulation of embodiment 173 is characterized in that the operating temperature is about 200°C. 180. The nicotine salt liquid formulation according to any one of embodiments 170-179, wherein the acid is a carboxylic acid. 181. The nicotine salt liquid formulation according to any one of embodiments 170-179, wherein the acid used to form the nicotine salt is an organic acid. 182. The nicotine salt liquid formulation of embodiment 181 is characterized in that the organic acid is a monocarboxylic acid, an aromatic acid, or a keto acid. 183. The nicotine salt liquid formulation of embodiment 181 is characterized in that the organic acid comprises formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, capric acid, citric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, phenylacetic acid, benzoic acid, pyruvic acid, levulinic acid, tartaric acid, lactic acid, malonic acid, succinic acid, fumaric acid, finic acid, gluconic acid, saccharic acid, salicylic acid, sorbic acid, malonic acid, or malic acid. 184. A liquid formulation according to any one of embodiments 170-179, characterized in that the acid used to form the nicotine salt is salicylic acid. 185. The nicotine salt liquid formulation according to any one of embodiments 170-179, wherein the acid used to form the nicotine salt is benzoic acid. 186. The nicotine salt liquid formulation according to any one of embodiments 170-179, wherein the acid used to form the nicotine salt is pyruvic acid. 187. The nicotine salt liquid formulation according to any one of embodiments 170-179, wherein the acid used to form the nicotine salt is sorbic acid. 188. The nicotine salt liquid formulation according to any one of embodiments 170-179, wherein the acid used to form the nicotine salt is lauric acid. 189. The nicotine salt liquid formulation according to any one of embodiments 170-179, wherein the acid used to form the nicotine salt is levulinic acid. 190. The nicotine salt liquid formulation according to any one of embodiments 170-179, characterized in that the nicotine salt comprises nicotine pyruvate. 191. The nicotine salt liquid formulation according to any one of embodiments 170-179, characterized in that the nicotine salt comprises nicotine salicylate. 192. The nicotine salt liquid formulation according to any one of embodiments 170-179, characterized in that the nicotine salt comprises nicotine sorbate. 193. The nicotine salt liquid formulation according to any one of embodiments 170-179, characterized in that the nicotine salt comprises nicotine laurate. 194. The nicotine salt liquid formulation according to any one of embodiments 170-179, characterized in that the nicotine salt comprises nicotine levulinate. 195. The nicotine salt liquid formulation according to any one of embodiments 170-179, characterized in that the nicotine salt comprises nicotine benzoate. 196. The nicotine salt liquid formulation according to any one of embodiments 170-195, wherein the liquid carrier comprises glycerol, propylene glycol, trimethylene glycol, water, ethanol, or a combination thereof. 197. A nicotine salt liquid formulation according to any one of embodiments 170-195, wherein the liquid carrier comprises propylene glycol and vegetable glycerin. 198. The nicotine salt liquid formulation according to any one of embodiments 170-195, wherein the liquid carrier comprises 20% to 50% of propylene glycol and 80% to 50% of vegetable glycerin. 199. The nicotine salt liquid formulation according to any one of embodiments 170-195, wherein the liquid carrier comprises 30% propylene glycol and 70% vegetable glycerin. 200. The nicotine salt liquid formulation according to any one of embodiments 170-199, wherein the nicotine salt is in an amount that forms about 0.5% to about 20% nicotine in the inhalable aerosol. 201. The nicotine salt liquid formulation according to any one of embodiments 170-199, wherein the nicotine salt is in an amount that forms about 1% to about 20% of the nicotine in the inhalable aerosol. 202. The nicotine salt liquid formulation according to any one of embodiments 170-201, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 25% (w / w). 203. The nicotine salt liquid formulation according to any one of embodiments 170-201, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 20% (w / w). 204. The nicotine salt liquid formulation according to any one of embodiments 170-201, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 18% (w / w). 205. The nicotine salt liquid formulation according to any one of embodiments 170-201, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 15% (w / w). 206. The nicotine salt liquid formulation according to any one of embodiments 170-201, wherein the liquid formulation has a nicotine concentration of about 4% (w / w) to about 12% (w / w). 207. The nicotine salt liquid formulation according to any one of embodiments 170-201, wherein the liquid formulation has a nicotine concentration of about 4% (w / w). 208. The nicotine salt liquid formulation according to any one of embodiments 170-201, wherein the liquid formulation has a nicotine concentration of about 2% (w / w). 209. The nicotine salt liquid formulation according to any one of embodiments 170-208, wherein the liquid formulation further comprises a flavoring material. 210. The nicotine salt liquid formulation according to any one of embodiments 170-209, characterized in that the formulation is non-corrosive to electronic cigarettes. 211. The nicotine salt liquid formulation according to any one of embodiments 170-210, wherein the acid is stable at or below the operating temperature of about 200°C. 212. The nicotine salt liquid formulation according to any one of embodiments 170-211, wherein the acid does not decompose below the operating temperature or about 200°C. 213. The nicotine salt liquid formulation according to any one of embodiments 170-212, characterized in that the acid does not oxidize at or below the operating temperature or about 200°C. 214. The nicotine salt liquid formulation according to any one of embodiments 170-213, characterized in that the formulation is non-corrosive to electronic cigarettes. 215. The nicotine salt liquid formulation according to any one of embodiments 170-214, characterized in that the formulation is non-toxic to users of electronic cigarettes. 216. The nicotine salt liquid formulation according to any one of embodiments 170-215, characterized in that it further comprises one or more additional nicotine salts in a biologically acceptable liquid carrier suitable for generating an inhalable aerosol upon heating. 217. The nicotine salt liquid formulation of embodiment 216 is characterized in that the second acid used to form the additional nicotine salt is selected from the group consisting of salicylic acid, sorbic acid, benzoic acid, pyruvic acid, lauric acid, and levulinic acid. 218. A nicotine salt liquid formulation for use in an electronic cigarette, the nicotine salt liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier, and characterized in that the acid used to form the nicotine salt is characterized by a vapor pressure of greater than 20 mmHg at 200°C. 219. A nicotine salt liquid formulation for use in an electronic cigarette, the nicotine salt liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier, and wherein the acid used to form the nicotine salt is characterized by a vapor pressure of about 20 to 200 mmHg at 200°C. 220. A nicotine salt liquid formulation for use in an electronic cigarette, the nicotine salt liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier, characterized in that the acid used to form the nicotine salt is further characterized by a melting point below 160°C, a boiling point above 160°C, and a difference of at least 50 degrees between the melting point and the boiling point. 221. A nicotine salt liquid formulation for use in an electronic cigarette, the nicotine salt liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is further characterized by a melting point at least 40 degrees below the operating temperature of the electronic cigarette, a boiling point no more than 40 degrees below the operating temperature of the electronic cigarette, and a difference of at least 50 degrees between the melting point and the boiling point. 222. The nicotine salt liquid formulation according to any one of embodiments 218-220, wherein the electronic cigarette heats the nicotine salt formulation to an operating temperature of 150°C to 250°C. 223. The nicotine salt liquid formulation according to any one of embodiments 218-220, wherein the electronic cigarette heats the nicotine salt formulation to an operating temperature of 180°C to 220°C. 224. The nicotine salt liquid formulation of any one of embodiments 218-220, wherein the electronic cigarette heats the nicotine salt formulation to an operating temperature of about 200°C. 225. The nicotine salt liquid formulation according to embodiment 221 is characterized in that the operating temperature is from 150°C to 250°C. 226. The nicotine salt liquid formulation according to embodiment 221 is characterized in that the operating temperature is from 180°C to 220°C. 227. The nicotine salt liquid formulation of embodiment 221 is characterized in that it has an operating temperature of about 200°C. 228. The nicotine salt liquid formulation according to any one of embodiments 218-227, wherein the acid is a carboxylic acid. 229. The nicotine salt liquid formulation according to any one of embodiments 218-227, wherein the acid used to form the nicotine salt is an organic acid. 230. The nicotine salt liquid formulation of embodiment 229 is characterized in that the organic acid is a monocarboxylic acid, an aromatic acid, or a keto acid. 231. The nicotine salt liquid formulation of embodiment 229 is characterized in that the organic acid comprises formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, capric acid, citric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, phenylacetic acid, benzoic acid, pyruvic acid, levulinic acid, tartaric acid, lactic acid, malonic acid, succinic acid, fumaric acid, finic acid, gluconic acid, saccharic acid, salicylic acid, sorbic acid, malonic acid, or malic acid. 232. A liquid formulation according to any one of embodiments 218-227, characterized in that the acid used to form the nicotine salt is salicylic acid. 233. The nicotine salt liquid formulation according to any one of embodiments 218-227, wherein the acid used to form the nicotine salt is benzoic acid. 234. The nicotine salt liquid formulation according to any one of embodiments 218-227, wherein the acid used to form the nicotine salt is pyruvic acid. 235. The nicotine salt liquid formulation according to any one of embodiments 218-227, wherein the acid used to form the nicotine salt is sorbic acid. 236. The nicotine salt liquid formulation according to any one of embodiments 218-227, wherein the acid used to form the nicotine salt is lauric acid. 237. The nicotine salt liquid formulation according to any one of embodiments 218-227, wherein the acid used to form the nicotine salt is levulinic acid. 238. The nicotine salt liquid formulation according to any one of embodiments 218-227, characterized in that the nicotine salt comprises nicotine pyruvate. 239. The nicotine salt liquid formulation according to any one of embodiments 218-227, characterized in that the nicotine salt comprises nicotine salicylate. 240. The nicotine salt liquid formulation according to any one of embodiments 218-227, characterized in that the nicotine salt comprises nicotine sorbate. 241. The nicotine salt liquid formulation according to any one of embodiments 218-227, characterized in that the nicotine salt comprises nicotine laurate. 242. The nicotine salt liquid formulation according to any one of embodiments 218-227, characterized in that the nicotine salt comprises nicotine levulinate. 243. The nicotine salt liquid formulation according to any one of embodiments 218-227, characterized in that the nicotine salt comprises nicotine benzoate. 244. The nicotine salt liquid formulation according to any one of embodiments 218-243, wherein the liquid carrier comprises glycerol, propylene glycol, trimethylene glycol, water, ethanol, or a combination thereof. 245. A nicotine salt liquid formulation according to any one of embodiments 218-243, characterized in that the liquid carrier comprises propylene glycol and vegetable glycerin. 246. The nicotine salt liquid formulation according to any one of embodiments 218-243, wherein the liquid carrier comprises 20% to 50% of propylene glycol and 80% to 50% of vegetable glycerin. 247. A nicotine salt liquid formulation according to any one of embodiments 218-243, wherein the liquid carrier comprises 30% propylene glycol and 70% vegetable glycerin. 248. The nicotine salt liquid formulation according to any one of embodiments 218-247, wherein the nicotine salt is in an amount that forms about 0.5% to about 20% nicotine in the inhalable aerosol. 249. The nicotine salt liquid formulation according to any one of embodiments 218-247, wherein the nicotine salt is in an amount that forms about 1% to about 20% of the nicotine in the inhalable aerosol. 250. The nicotine salt liquid formulation according to any one of embodiments 218-247, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 25% (w / w). 251. The nicotine salt liquid formulation according to any one of embodiments 218-247, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 20% (w / w). 252. The nicotine salt liquid formulation according to any one of embodiments 218-247, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 18% (w / w). 253. The nicotine salt liquid formulation according to any one of embodiments 218-247, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 15% (w / w). 254. The nicotine salt liquid formulation according to any one of embodiments 218-247, wherein the liquid formulation has a nicotine concentration of about 4% (w / w) to about 12% (w / w). 255. The nicotine salt liquid formulation according to any one of embodiments 218-247, wherein the liquid formulation has a nicotine concentration of about 4% (w / w). 256. The nicotine salt liquid formulation according to any one of embodiments 218-247, wherein the liquid formulation has a nicotine concentration of about 2% (w / w). 257. The nicotine salt liquid formulation according to any one of embodiments 218-256, characterized in that the liquid formulation further comprises a flavoring material. 258. The nicotine salt liquid formulation according to any one of embodiments 218-257, characterized in that the formulation is non-corrosive to electronic cigarettes. 259. The nicotine salt liquid formulation according to any one of embodiments 218-258, wherein the acid is stable at or below the operating temperature of about 200°C. 260. The nicotine salt liquid formulation according to any one of embodiments 218-259, wherein the acid does not decompose at or below the operating temperature or about 200°C. 261. The nicotine salt liquid formulation according to any one of embodiments 218-260, wherein the acid does not oxidize at or below the operating temperature or about 200°C. 262. The nicotine salt liquid formulation according to any one of embodiments 218-261, characterized in that the formulation is non-corrosive to electronic cigarettes. 263. The nicotine salt liquid formulation according to any one of embodiments 218-262, characterized in that the formulation is non-toxic to users of electronic cigarettes. 264. The nicotine salt liquid formulation according to any one of embodiments 218-263, characterized in that it further comprises one or more additional nicotine salts in a biologically acceptable liquid carrier suitable for generating an inhalable aerosol upon heating. 265. The nicotine salt liquid formulation of embodiment 264 is characterized in that the second acid used to form the additional nicotine salt is selected from the group consisting of salicylic acid, sorbic acid, benzoic acid, pyruvic acid, lauric acid, and levulinic acid. 266. Use of a nicotine salt formulation for delivering nicotine to a user from an electronic cigarette, wherein the nicotine salt formulation comprises a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is characterized by a vapor pressure of greater than 20 mmHg at 200°C, and wherein the nicotine salt formulation is heated by the electronic cigarette to produce an aerosol inhalable by the user. 267. Use of a nicotine salt formulation for delivering nicotine to a user from an electronic cigarette, the nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier, the acid used to form the nicotine salt being characterized by a vapor pressure of approximately 20 to 200 mmHg at 200°C, and the nicotine salt formulation being heated by the electronic cigarette to produce an aerosol inhalable by the user. 268. Use of a nicotine salt formulation for delivering nicotine to a user from an electronic cigarette, the nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier, the acid used to form the nicotine salt further characterized by a melting point below 160°C, a boiling point above 160°C, and a difference of at least 50 degrees between the melting point and the boiling point, and the nicotine salt formulation is heated by the electronic cigarette to produce an aerosol inhalable by the user. 269. There is provided a use of a nicotine salt formulation for delivering nicotine to a user's blood from an electronic cigarette, wherein the nicotine salt formulation in the electronic cigarette is heated to form an aerosol, and the aerosol delivers a nicotine level in the user's blood that is at least 5 ng / mL for approximately 1.5 minutes after the first of 10 puffs of the aerosol, with each puff being spaced 30 seconds apart. 270. Use of a nicotine salt formulation for delivering nicotine to a user from an electronic cigarette, the nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is further characterized by a melting point at least 40 degrees below the operating temperature of the electronic cigarette, a boiling point no more than 40 degrees below the operating temperature of the electronic cigarette, and a difference of at least 50 degrees between the melting point and the boiling point. Nicotine salt formulations are heated by the e-cigarette to produce an aerosol that can be inhaled by the user. 271. The use according to any one of embodiments 266-269, wherein the electronic cigarette heats the nicotine salt formulation to an operating temperature of 150°C to 250°C. 272. The use according to any one of embodiments 266-269, wherein the electronic cigarette heats the nicotine salt formulation to an operating temperature of 180°C to 220°C. 273. The use according to any one of embodiments 266-269, wherein the electronic cigarette heats the nicotine salt formulation to an operating temperature of 200°C. 274. The use according to any one of embodiments 270, characterized in that the operating temperature is from 150°C to 250°C. 275. The use according to any one of embodiments 270, characterized in that the operating temperature is from 180°C to 220°C. 276. The use according to any one of embodiments 270, wherein the operating temperature is about 200°C. 277. The use according to any one of embodiments 266-276, characterized in that the aerosol comprises a condensate of a nicotine salt. 278. The use according to any one of embodiments 266-276, wherein the aerosol comprises a condensate of free base nicotine. 279. The use according to any one of embodiments 266-276, wherein the aerosol comprises a condensate of free base nicotine and a condensate of a carrier. 280. The use according to any one of embodiments 266-276, wherein the aerosol comprises a condensate of free base nicotine and a condensate of an acid. 281. The use according to any one of embodiments 266-280, wherein the aerosol comprises condensate having a particle size of about 0.1 microns to about 5 microns. 282. The use according to any one of embodiments 266-280, wherein the aerosol comprises condensate having a particle size of about 0.1 microns to about 1 or 2 microns. 283. The use according to any one of embodiments 266-280, wherein the aerosol comprises condensate having a particle size of about 0.1 microns to about 0.7 microns. 284. The use according to any one of embodiments 266-280, wherein the aerosol comprises condensate having a particle size of about 0.3 microns to about 0.4 microns. 285. The use according to any one of embodiments 266-284, wherein the acid is a carboxylic acid. 286. The use according to any one of embodiments 266-284, wherein the acid used to form the nicotine salt is an organic acid. 287. The method according to any one of embodiments 286, wherein the organic acid is a monocarboxylic acid, an aromatic acid, or a keto acid. 288. The method according to any one of embodiments 286, wherein the organic acid comprises formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, capric acid, citric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, phenylacetic acid, benzoic acid, pyruvic acid, levulinic acid, tartaric acid, lactic acid, malonic acid, succinic acid, fumaric acid, finic acid, gluconic acid, saccharic acid, salicylic acid, sorbic acid, malonic acid, or malic acid. 289. The use according to any one of embodiments 266-284, wherein the acid used to form the nicotine salt is salicylic acid. 290. The use according to any one of embodiments 266-284, wherein the acid used to form the nicotine salt is benzoic acid. 291. The use according to any one of embodiments 266-284, wherein the acid used to form the nicotine salt is pyruvic acid. 292. The use according to any one of embodiments 266-284, wherein the acid used to form the nicotine salt is sorbic acid. 293. The use according to any one of embodiments 266-284, wherein the acid used to form the nicotine salt is lauric acid. 294. The use according to any one of embodiments 266-284, wherein the acid used to form the nicotine salt is levulinic acid. 295. The use according to any one of embodiments 266-284, characterized in that the nicotine salt comprises nicotine pyruvate. 296. The use according to any one of embodiments 266-284, characterized in that the nicotine salt comprises nicotine salicylate. 297. The use according to any one of embodiments 266-284, wherein the nicotine salt comprises nicotine sorbate. 298. The use according to any one of embodiments 266-284, characterized in that the nicotine salt comprises nicotine laurate. 299. The use according to any one of embodiments 266-284, characterized in that the nicotine salt comprises nicotine levulinate. 300. The use according to any one of embodiments 266-284, characterized in that the nicotine salt comprises nicotine benzoate. 301. The use according to any one of embodiments 266-300, wherein the liquid carrier comprises glycerol, propylene glycol, trimethylene glycol, water, ethanol, or a combination thereof. 302. The use according to any one of embodiments 266-300, wherein the liquid carrier comprises propylene glycol and vegetable glycerin. 303. The use according to any one of embodiments 266-300, wherein the liquid carrier comprises 20% to 50% of propylene glycol and 80% to 50% of vegetable glycerin. 304. The use according to any one of embodiments 266-300, wherein the liquid carrier comprises 30% propylene glycol and 70% vegetable glycerin. 305. The use according to any one of embodiments 266-304, wherein the nicotine salt is in an amount that forms about 0.5% to about 20% nicotine in the inhalable aerosol. 306. The use according to any one of embodiments 266-304, wherein the nicotine salt is in an amount that forms about 1% to about 20% of nicotine in the inhalable aerosol. 307. The use according to any one of embodiments 266-306, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 25% (w / w). 308. The use according to any one of embodiments 266-306, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 20% (w / w). 309. The use according to any one of embodiments 266-306, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 18% (w / w). 310. The use according to any one of embodiments 266-306, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 15% (w / w). 311. The use according to any one of embodiments 266-306, wherein the liquid formulation has a nicotine concentration of about 4% (w / w) to about 12% (w / w). 312. The use according to any one of embodiments 266-306, wherein the liquid formulation has a nicotine concentration of about 4% (w / w). 313. The use according to any one of embodiments 266-306, wherein the liquid formulation has a nicotine concentration of about 2% (w / w). 314. The use according to any one of embodiments 266-313, characterized in that the liquid formulation further comprises a flavoring material. 315. The use according to any one of embodiments 266-314, wherein the formulation is non-corrosive to electronic cigarettes. 316. The use according to any one of embodiments 266-315, wherein the acid is stable at the operating temperature or below about 200°C. 317. The use according to any one of embodiments 266-316, characterized in that the acid does not decompose at the operating temperature or below about 200 ° C. 318. The use according to any one of embodiments 266-317, characterized in that the acid does not oxidize at the operating temperature or below about 200°C. 319. The use according to any one of embodiments 266-318, characterized in that the formulation is non-corrosive to electronic cigarettes. 320. The use according to any one of embodiments 266-319, wherein the formulation is non-toxic to users of electronic cigarettes. 321. The use according to any one of embodiments 266-320, characterized in that it further comprises one or more additional nicotine salts in a biologically acceptable liquid carrier suitable for generating an inhalable aerosol upon heating. 322. The use according to embodiment 321, characterized in that the second acid used to form the additional nicotine salt is selected from the group consisting of salicylic acid, sorbic acid, benzoic acid, pyruvic acid, lauric acid, and levulinic acid. 323. A cartomizer for an electronic cigarette, the cartomizer comprising: a nicotine salt liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is characterized by a vapor pressure of greater than 20 mmHg at 200°C; an atomizer including a heating element in fluid communication with the nicotine salt liquid formulation; and a fluid storage compartment for storing a nicotine salt liquid formulation. 324. A cartomizer for an electronic cigarette, the cartomizer comprising: a nicotine salt liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is characterized by a vapor pressure of about 20 to 200 mmHg at 200°C; an atomizer including a heating element in fluid communication with the nicotine salt liquid formulation; and a fluid storage compartment for storing a nicotine salt liquid formulation. 325. A cartomizer for an electronic cigarette, the cartomizer comprising: a nicotine salt liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is further characterized by a melting point below 160°C, a boiling point above 160°C, and a difference of at least 50 degrees between the melting point and the boiling point; an atomizer including a heating element in fluid communication with the nicotine salt liquid formulation; and a fluid storage compartment for storing a nicotine salt liquid formulation. 326. A cartomizer for an electronic cigarette, the cartomizer comprising: a nicotine salt liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is further characterized by a melting point at least 40 degrees below the operating temperature of the electronic cigarette, a boiling point no more than 40 degrees below the operating temperature of the electronic cigarette, and a difference of at least 50 degrees between the melting point and the boiling point; an atomizer including a heating element in fluid communication with the nicotine salt liquid formulation; and a fluid storage compartment for storing a nicotine salt liquid formulation. 327. The cartomizer of any one of embodiments 323-325, wherein the electronic cigarette heats the nicotine salt formulation to an operating temperature of 150°C to 250°C. 328. The cartomizer of any one of embodiments 323-325, wherein the electronic cigarette heats the nicotine salt formulation to an operating temperature of 180°C to 220°C. 329. The cartomizer of any one of embodiments 323-325, wherein the electronic cigarette heats the nicotine salt formulation to an operating temperature of about 200°C. 330. The cartomizer according to embodiment 326 is characterized in that the operating temperature is from 150°C to 250°C. 331. The cartomizer according to embodiment 326 is characterized in that the operating temperature is from 180°C to 220°C. 332. The cartomizer according to embodiment 326 is characterized in that the operating temperature is about 200°C. 333. The cartomizer according to any one of embodiments 323-332, wherein the cartomizer further comprises a mouthpiece. 334. The cartomizer according to any one of embodiments 323-333, wherein the acid is a carboxylic acid. 335. A cartomizer according to any one of embodiments 323-333, characterized in that the acid used to form the nicotine salt is an organic acid. 336. The cartomizer according to embodiment 335, wherein the organic acid is a monocarboxylic acid, an aromatic acid, or a keto acid. 337. The cartomizer according to embodiment 335, wherein the organic acid comprises formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, capric acid, citric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, phenylacetic acid, benzoic acid, pyruvic acid, levulinic acid, tartaric acid, lactic acid, malonic acid, succinic acid, fumaric acid, finic acid, gluconic acid, saccharic acid, salicylic acid, sorbic acid, malonic acid, or malic acid. 338. A cartomizer according to any one of embodiments 323-333, characterized in that the acid used to form the nicotine salt is salicylic acid. 339. The cartomizer according to any one of embodiments 323-333, characterized in that the acid used to form the nicotine salt is benzoic acid. 340. A cartomizer according to any one of embodiments 323-333, characterized in that the acid used to form the nicotine salt is pyruvic acid. 341. A cartomizer according to any one of embodiments 323-333, characterized in that the acid used to form the nicotine salt is sorbic acid. 342. A cartomizer according to any one of embodiments 323-333, characterized in that the acid used to form the nicotine salt is lauric acid. 343. A cartomizer according to any one of embodiments 323-333, characterized in that the acid used to form the nicotine salt is levulinic acid. 344. A cartomizer according to any one of embodiments 323-333, characterized in that the nicotine salt comprises nicotine pyruvate. 345. A cartomizer according to any one of embodiments 323-333, characterized in that the nicotine salt comprises nicotine salicylate. 346. The cartomizer according to any one of embodiments 323-333, characterized in that the nicotine salt comprises nicotine sorbate. 347. A cartomizer according to any one of embodiments 323-333, characterized in that the nicotine salt comprises nicotine laurate. 348. A cartomizer according to any one of embodiments 323-333, characterized in that the nicotine salt comprises nicotine levulinate. 349. The cartomizer according to any one of embodiments 323-333, characterized in that the nicotine salt comprises nicotine benzoate. 350. The cartomizer of any one of embodiments 323-349, wherein the liquid carrier comprises glycerol, propylene glycol, trimethylene glycol, water, ethanol, or a combination thereof. 351. The cartomizer according to any one of embodiments 323-349, wherein the liquid carrier comprises propylene glycol and vegetable glycerin. 352. The cartomizer according to any one of embodiments 323-349, wherein the liquid carrier comprises 20% to 50% propylene glycol and 80% to 50% vegetable glycerin. 353. The cartomizer of any one of embodiments 323-349, wherein the liquid carrier comprises 30% propylene glycol and 70% vegetable glycerin. 354. The cartomizer of any one of embodiments 323-353, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 25% (w / w). 355. The cartomizer of any one of embodiments 323-353, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 20% (w / w). 356. The cartomizer of any one of embodiments 323-353, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 18% (w / w). 357. The cartomizer of any one of embodiments 323-353, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 15% (w / w). 358. The cartomizer of any one of embodiments 323-353, wherein the liquid formulation has a nicotine concentration of about 4% (w / w) to about 12% (w / w). 359. The cartomizer according to any one of embodiments 323-353, wherein the liquid formulation has a nicotine concentration of about 4% (w / w). 360. The cartomizer according to any one of embodiments 323-353, wherein the liquid formulation has a nicotine concentration of about 2% (w / w). 361. The cartomizer according to any one of embodiments 323-360, wherein the electronic cigarette is configured to generate an aerosol that can be inhaled by a user. 362. The cartomizer according to embodiment 361, wherein the aerosol comprises a condensate of a nicotine salt. 363. The cartomizer according to embodiment 361, wherein the aerosol comprises a condensate of free base nicotine. 364. The cartomizer of embodiment 361 is characterized in that the aerosol comprises a condensate of free base nicotine and a condensate of a carrier. 365. The cartomizer according to embodiment 361, wherein the aerosol comprises a condensate of free base nicotine and a condensate of acid. 366. The cartomizer of any one of embodiments 361-365, wherein the aerosol comprises condensate having a particle size of about 0.1 microns to about 5 microns. 367. The cartomizer of any one of embodiments 361-365, wherein the aerosol comprises condensate having a particle size of about 0.1 microns to about 1 or 2 microns. 368. The cartomizer of any one of embodiments 361-365, wherein the aerosol comprises condensate having a particle size of about 0.1 microns to about 0.7 microns. 369. The cartomizer of any one of embodiments 361-365, wherein the aerosol comprises condensate having a particle size of about 0.3 microns to about 0.4 microns. 370. The cartomizer of any one of embodiments 361-369, wherein the nicotine salt is in an amount to form about 0.5% to about 20% nicotine in the inhalable aerosol. 371. The cartomizer according to any one of embodiments 361-369, wherein the nicotine salt is in an amount to form about 1% to about 20% nicotine in the inhalable aerosol. 372. A cartomizer according to any one of embodiments 323-371, characterized in that the liquid formulation further comprises a flavoring material. 373. The cartomizer according to any one of embodiments 323-372, characterized in that the formulation is non-corrosive to electronic cigarettes. 374. The cartomizer according to any one of embodiments 323-373, wherein the acid is stable at or below the operating temperature of about 200°C. 375. The cartomizer according to any one of embodiments 323-374, wherein the acid does not decompose at or below the operating temperature or about 200°C. 376. The cartomizer according to any one of embodiments 323-375, characterized in that the acid does not oxidize at or below the operating temperature or about 200°C. 377. The cartomizer according to any one of embodiments 323-376, characterized in that the formulation is non-corrosive to electronic cigarettes. 378. The cartomizer according to any one of embodiments 323-377, characterized in that the formulation is non-toxic to users of electronic cigarettes. 379. The cartomizer according to any one of embodiments 323-378, characterized in that it further comprises one or more additional nicotine salts in a biologically acceptable liquid carrier suitable for producing an inhalable aerosol upon heating. 380. The cartomizer according to embodiment 379, wherein the second acid used to form the additional nicotine salt is selected from the group consisting of salicylic acid, sorbic acid, benzoic acid, pyruvic acid, lauric acid, and levulinic acid. 381. An electronic cigarette for generating an inhalable aerosol, comprising: The e-cigarette: fluid storage compartment; heater; and a nicotine salt liquid formulation in a fluid storage compartment comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is characterized by a vapor pressure of greater than 20 mmHg at 200°C; Battery; and A mouthpiece is included. 382. An electronic cigarette for generating an inhalable aerosol, comprising: The e-cigarette: fluid storage compartment; heater; and a nicotine salt liquid formulation in a fluid storage compartment comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is characterized by a vapor pressure of about 20 to 200 mmHg at 200°C; Battery; and A mouthpiece is included. 383. An electronic cigarette for generating an inhalable aerosol, comprising: The e-cigarette: fluid storage compartment; heater; and a nicotine salt liquid formulation in a fluid storage compartment comprising a nicotine salt in a biologically acceptable liquid carrier, wherein an acid used to form the nicotine salt is further characterized by a melting point below 160°C, a boiling point above 160°C, and a difference of at least 50 degrees between the melting point and the boiling point; Battery; and A mouthpiece is included. 384. An electronic cigarette for generating an inhalable aerosol, comprising: The e-cigarette: fluid storage compartment; heater; and a nicotine salt liquid formulation in a fluid storage compartment, comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is further characterized by a melting point at least 40 degrees below the operating temperature of the electronic cigarette, a boiling point that is no more than 40 degrees below the operating temperature of the electronic cigarette, and a difference between the melting point and the boiling point of at least 50 degrees; the nicotine salt liquid formulation; Battery; and A mouthpiece is included. 385. The electronic cigarette according to any one of embodiments 381-384, wherein the heater includes a heater chamber, a fluid wick, and a resistive heating element in contact with the fluid wick. 386. The electronic cigarette according to any one of embodiments 381-384, wherein the mouthpiece, the heater, and the fluid storage compartment form a cartomizer separable from the battery. 387. The electronic cigarette according to any one of embodiments 381-384, wherein the heater and the fluid storage compartment form a cartomizer that is separable from the battery and the mouthpiece. 388. The electronic cigarette according to any one of embodiments 381-384, wherein the fluid storage compartment is separable from the heater, the battery, and the mouthpiece. 389. The electronic cigarette according to any one of embodiments 381-383, characterized in that the electronic cigarette heats the nicotine salt formulation to an operating temperature of 150°C to 250°C. 390. The electronic cigarette according to any one of embodiments 381-383, wherein the electronic cigarette heats the nicotine salt formulation to an operating temperature of 180°C to 220°C. 391. The electronic cigarette according to any one of embodiments 381-383, wherein the electronic cigarette heats the nicotine salt formulation to an operating temperature of about 200°C. 392. The electronic cigarette according to embodiment 384 is characterized in that the operating temperature is from 150°C to 250°C. 393. The electronic cigarette according to embodiment 384 is characterized in that the operating temperature is from 180°C to 220°C. 394. The electronic cigarette of embodiment 384 is characterized in that the operating temperature is about 200°C. 395. The electronic cigarette according to any one of embodiments 381-394, characterized in that the aerosol comprises a condensate of a nicotine salt. 396. The electronic cigarette according to any one of embodiments 381-394, wherein the aerosol comprises a condensate of free base nicotine. 397. The electronic cigarette according to any one of embodiments 381-394, wherein the aerosol comprises a condensate of free base nicotine and a condensate of a carrier. 398. The electronic cigarette according to any one of embodiments 381-394, wherein the aerosol comprises a condensate of free base nicotine and a condensate of an acid. 399. The electronic cigarette of any one of embodiments 381-398, wherein the aerosol comprises condensate having a particle size of about 0.1 microns to about 5 microns. 400. The electronic cigarette of any one of embodiments 381-398, wherein the aerosol comprises condensate having a particle size of about 0.1 microns to about 1 or 2 microns. 401. The electronic cigarette of any one of embodiments 381-398, wherein the aerosol comprises condensate having a particle size of about 0.1 microns to about 0.7 microns. 402. The electronic cigarette of any one of embodiments 381-398, wherein the aerosol comprises condensate having a particle size of about 0.3 microns to about 0.4 microns. 403. The electronic cigarette according to any one of embodiments 381-402, wherein the acid is a carboxylic acid. 404. The electronic cigarette according to any one of embodiments 381-402, wherein the acid used to form the nicotine salt is an organic acid. 405. The electronic cigarette according to any one of embodiments 404, wherein the organic acid is a monocarboxylic acid, an aromatic acid, or a keto acid. 406. The electronic cigarette of embodiment 404 is characterized in that the organic acid comprises formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, capric acid, citric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, phenylacetic acid, benzoic acid, pyruvic acid, levulinic acid, tartaric acid, lactic acid, malonic acid, succinic acid, fumaric acid, finic acid, gluconic acid, saccharic acid, salicylic acid, sorbic acid, malonic acid, or malic acid. 407. The electronic cigarette according to any one of embodiments 381-402, wherein the acid used to form the nicotine salt is salicylic acid. 408. The electronic cigarette according to any one of embodiments 381-402, wherein the acid used to form the nicotine salt is benzoic acid. 409. The electronic cigarette according to any one of embodiments 381-402, wherein the acid used to form the nicotine salt is pyruvic acid. 410. The electronic cigarette according to any one of embodiments 381-402, wherein the acid used to form the nicotine salt is sorbic acid. 411. The electronic cigarette according to any one of embodiments 381-402, wherein the acid used to form the nicotine salt is lauric acid. 412. The electronic cigarette according to any one of embodiments 381-402, wherein the acid used to form the nicotine salt is levulinic acid. 413. The electronic cigarette according to any one of embodiments 381-402, characterized in that the nicotine salt comprises nicotine pyruvate. 414. The electronic cigarette according to any one of embodiments 381-402, wherein the nicotine salt comprises nicotine salicylate. 415. The electronic cigarette according to any one of embodiments 381-402, characterized in that the nicotine salt comprises nicotine sorbate. 416. The electronic cigarette according to any one of embodiments 381-402, characterized in that the nicotine salt comprises nicotine laurate. 417. The electronic cigarette according to any one of embodiments 381-402, characterized in that the nicotine salt comprises nicotine levulinate. 418. The electronic cigarette according to any one of embodiments 381-402, characterized in that the nicotine salt comprises nicotine benzoate. 419. The electronic cigarette according to any one of embodiments 381-419, wherein the liquid carrier comprises glycerol, propylene glycol, trimethylene glycol, water, ethanol, or a combination thereof. 420. The electronic cigarette according to any one of embodiments 381-419, wherein the liquid carrier comprises propylene glycol and vegetable glycerin. 421. The electronic cigarette according to any one of embodiments 381-419, wherein the liquid carrier comprises 20% to 50% propylene glycol and 80% to 50% vegetable glycerin. 422. The electronic cigarette according to any one of embodiments 381-419, wherein the liquid carrier comprises 30% propylene glycol and 70% vegetable glycerin. 423. The electronic cigarette of any one of embodiments 381-422, wherein the nicotine salt is in an amount that forms about 0.5% to about 20% nicotine in the inhalable aerosol. 424. The electronic cigarette of any one of embodiments 381-422, wherein the nicotine salt is in an amount that forms about 1% to about 20% nicotine in the inhalable aerosol. 425. The electronic cigarette of any one of embodiments 381-424, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 25% (w / w). 426. The electronic cigarette according to any one of embodiments 381-424, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 20% (w / w). 427. The electronic cigarette according to any one of embodiments 381-424, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 18% (w / w). 428. The electronic cigarette according to any one of embodiments 381-424, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 15% (w / w). 429. The electronic cigarette of any one of embodiments 381-424, wherein the liquid formulation has a nicotine concentration of about 4% (w / w) to about 12% (w / w). 430. The electronic cigarette according to any one of embodiments 381-424, wherein the liquid formulation has a nicotine concentration of about 4% (w / w). 431. The electronic cigarette according to any one of embodiments 381-424, wherein the liquid formulation has a nicotine concentration of about 2% (w / w). 432. The electronic cigarette according to any one of embodiments 381-431, characterized in that the liquid formulation further comprises a flavoring material. 433. The electronic cigarette according to any one of embodiments 381-432, characterized in that the formulation is non-corrosive to the electronic cigarette. 434. The electronic cigarette according to any one of embodiments 381-433, wherein the acid is stable at or below the operating temperature of about 200°C. 435. The electronic cigarette according to any one of embodiments 381-434, wherein the acid does not decompose below the operating temperature or about 200°C. 436. The electronic cigarette according to any one of embodiments 381-435, wherein the acid does not oxidize at or below the operating temperature or about 200°C. 437. The electronic cigarette according to any one of embodiments 381-436, characterized in that the formulation is non-corrosive to the electronic cigarette. 438. The electronic cigarette according to any one of embodiments 381-437, characterized in that the formulation is non-toxic to the user of the electronic cigarette. 439. The electronic cigarette according to any one of embodiments 381-438, characterized in that it further comprises one or more additional nicotine salts in a biologically acceptable liquid carrier suitable for generating an inhalable aerosol upon heating. 440. The electronic cigarette of embodiment 439, wherein the second acid used to form the additional nicotine salt is selected from the group consisting of salicylic acid, sorbic acid, benzoic acid, pyruvic acid, lauric acid, and levulinic acid. 441. A cartridge in an electronic cigarette comprising a fluid storage compartment, the fluid storage compartment storing a nicotine salt liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier, characterized in that the acid used to form the nicotine salt is characterized by a vapor pressure of greater than 20 mmHg at 200°C. 442. A cartridge in an electronic cigarette including a fluid storage compartment, wherein the fluid storage compartment stores a nicotine salt liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier, and wherein the acid used to form the nicotine salt is characterized by a vapor pressure of about 20 to 200 mmHg at 200°C. 443. A cartridge within an electronic cigarette comprising a fluid storage compartment, the fluid storage compartment storing a nicotine salt liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is further characterized by a melting point below 160°C, a boiling point above 160°C, and a difference of at least 50 degrees between the melting point and the boiling point. 444. A cartridge in an electronic cigarette comprising a fluid storage compartment, the fluid storage compartment storing a nicotine salt liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is further characterized by a melting point at least 40 degrees below the operating temperature of the electronic cigarette, a boiling point no more than 40 degrees below the operating temperature of the electronic cigarette, and a difference of at least 50 degrees between the melting point and the boiling point. 445. The cartridge according to any one of embodiments 441-444, characterized in that the cartridge is separable from the electronic cigarette. 446. The cartridge according to any one of embodiments 441-445, wherein the acid is a carboxylic acid. 447. The cartridge according to one of embodiments 441-445, characterized in that the acid used to form the nicotine salt is an organic acid. 448. The cartridge according to any one of embodiments 447, wherein the organic acid is a monocarboxylic acid, an aromatic acid, or a keto acid. 449. The cartridge according to embodiment 447, wherein the organic acid comprises formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, capric acid, citric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, phenylacetic acid, benzoic acid, pyruvic acid, levulinic acid, tartaric acid, lactic acid, malonic acid, succinic acid, fumaric acid, finic acid, gluconic acid, saccharic acid, salicylic acid, sorbic acid, malonic acid, or malic acid. 450. The cartridge according to one of embodiments 441-445, wherein the acid used to form the nicotine salt is salicylic acid. 451. The cartridge according to one of embodiments 441-445, wherein the acid used to form the nicotine salt is benzoic acid. 452. The cartridge according to one of embodiments 441-445, characterized in that the acid used to form the nicotine salt is pyruvic acid. 453. The cartridge according to one of embodiments 441-445, wherein the acid used to form the nicotine salt is sorbic acid. 454. The cartridge according to one of embodiments 441-445, characterized in that the acid used to form the nicotine salt is lauric acid. 455. The cartridge according to one of embodiments 441-445, wherein the acid used to form the nicotine salt is levulinic acid. 456. The cartridge according to any one of embodiments 441-445, wherein the nicotine salt comprises nicotine pyruvate. 457. The cartridge according to any one of embodiments 441-445, wherein the nicotine salt comprises nicotine salicylate. 458. The cartridge according to any one of embodiments 441-445, wherein the nicotine salt comprises nicotine sorbate. 459. The cartridge according to any one of embodiments 441-445, wherein the nicotine salt comprises nicotine laurate. 460. The cartridge according to any one of embodiments 441-445, wherein the nicotine salt comprises nicotine levulinate. 461. The cartridge according to any one of embodiments 441-445, wherein the nicotine salt comprises nicotine benzoate. 462. The cartridge according to any one of embodiments 441-461, wherein the liquid carrier comprises glycerol, propylene glycol, trimethylene glycol, water, ethanol, or a combination thereof. 463. The cartridge according to any one of embodiments 441-461, wherein the liquid carrier comprises propylene glycol and vegetable glycerin. 464. The cartridge according to any one of embodiments 441-461, wherein the liquid carrier comprises 20% to 50% propylene glycol and 80% to 50% vegetable glycerin. 465. The cartridge according to any one of embodiments 441-461, wherein the liquid carrier comprises 30% propylene glycol and 70% vegetable glycerin. 466. The cartridge according to any one of embodiments 441-465, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 25% (w / w). 467. The cartridge according to any one of embodiments 441-465, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 20% (w / w). 468. The cartridge according to any one of embodiments 441-465, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 18% (w / w). 469. The cartridge according to any one of embodiments 441-465, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 15% (w / w). 470. The cartridge according to any one of embodiments 441-465, wherein the liquid formulation has a nicotine concentration of about 4% (w / w) to about 12% (w / w). 471. The cartridge according to any one of embodiments 441-465, wherein the liquid formulation has a nicotine concentration of about 4% (w / w). 472. The cartridge according to any one of embodiments 441-465, wherein the liquid formulation has a nicotine concentration of about 2% (w / w). 473. The cartridge according to any one of embodiments 441-472, wherein the liquid formulation further comprises a flavoring material. 474. The cartridge according to any one of embodiments 441-473, characterized in that the formulation is non-corrosive to electronic cigarettes. 475. The cartridge according to any one of embodiments 441-474, wherein the acid is stable at or below the operating temperature of about 200°C. 476. The cartridge according to any one of embodiments 441-475, wherein the acid does not decompose at or below the operating temperature or about 200°C. 477. The cartridge according to any one of embodiments 441-476, wherein the acid does not oxidize at or below the operating temperature or about 200°C. 478. The cartridge according to any one of embodiments 441-477, characterized in that the formulation is non-corrosive to electronic cigarettes. 479. The cartridge according to any one of embodiments 441-478, characterized in that the formulation is non-toxic to users of electronic cigarettes. 480. The cartridge according to any one of embodiments 441-479, characterized in that it further comprises one or more additional nicotine salts in a biologically acceptable liquid carrier suitable for generating an inhalable aerosol upon heating. 481. The cartridge according to embodiment 480, wherein the second acid used to form the additional nicotine salt is selected from the group consisting of salicylic acid, sorbic acid, benzoic acid, pyruvic acid, lauric acid, and levulinic acid. 482. A kit comprising: (a) An electronic cigarette for generating an inhalable aerosol, comprising: i. a device body including a cartridge container; ii. A cartridge comprising a fluid storage compartment, the fluid storage compartment storing a nicotine salt liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein an acid used to form the nicotine salt is characterized by a vapor pressure of greater than 20 mmHg at 200°C; iii.Heater; iv. Batteries; and v. Mouthpieces, including electronic cigarettes; and (b) instructions for using the electronic cigarette to generate an inhalable aerosol. 483. A kit, The kit comprises: (a) An electronic cigarette for generating an inhalable aerosol, comprising: i. a device body including a cartridge container; ii. A cartridge comprising a fluid storage compartment, the fluid storage compartment storing a nicotine salt liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is characterized by a vapor pressure of about 20 to 200 mmHg at 200°C; iii.Heater; iv. Batteries; and v. Mouthpieces, including electronic cigarettes; and (b) instructions for using the electronic cigarette to generate an inhalable aerosol. 484. A kit, The kit comprises: (a) An electronic cigarette for generating an inhalable aerosol, comprising: i. a device body including a cartridge container; ii. A cartridge comprising a fluid storage compartment, the fluid storage compartment storing a nicotine salt liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein an acid used to form the nicotine salt is further characterized by a melting point below 160°C, a boiling point above 160°C, and a difference of at least 50 degrees between the melting point and the boiling point; iii.Heater; iv. Batteries; and v. Mouthpieces, including electronic cigarettes; and (b) instructions for using the electronic cigarette to generate an inhalable aerosol. 485. A kit, The kit comprises: (a) An electronic cigarette for generating an inhalable aerosol, comprising: i. a device body including a cartridge container; ii. A cartridge comprising a fluid storage compartment, the fluid storage compartment storing a nicotine salt liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is further characterized by a melting point at least 40 degrees below the operating temperature of the electronic cigarette, a boiling point no more than 40 degrees below the operating temperature of the electronic cigarette, and a difference between the melting point and the boiling point of at least 50 degrees; iii.Heater; iv. Batteries; and v. Mouthpieces, including electronic cigarettes; and (b) instructions for using the electronic cigarette to generate an inhalable aerosol. 486. The kit according to any one of embodiments 482-485, wherein the acid is a carboxylic acid. 487. The kit of any one of embodiments 482-485, wherein the acid used to form the nicotine salt is an organic acid. 488. The kit according to embodiment 487, wherein the organic acid is a monocarboxylic acid, an aromatic acid, or a keto acid. 489. The kit according to embodiment 487, wherein the organic acid comprises formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, capric acid, citric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, phenylacetic acid, benzoic acid, pyruvic acid, levulinic acid, tartaric acid, lactic acid, malonic acid, succinic acid, fumaric acid, finic acid, gluconic acid, saccharic acid, salicylic acid, sorbic acid, malonic acid, or malic acid. 490. The kit according to any one of embodiments 482-485, wherein the acid used to form the nicotine salt is salicylic acid. 491. The kit according to any one of embodiments 482-485, wherein the acid used to form the nicotine salt is benzoic acid. 492. The kit according to any one of embodiments 482-485, wherein the acid used to form the nicotine salt is pyruvic acid. 493. The kit according to any one of embodiments 482-485, wherein the acid used to form the nicotine salt is sorbic acid. 494. The kit according to any one of embodiments 482-485, wherein the acid used to form the nicotine salt is lauric acid. 495. The kit according to any one of embodiments 482-485, wherein the acid used to form the nicotine salt is levulinic acid. 496. The kit according to any one of embodiments 482-485, characterized in that the nicotine salt comprises nicotine pyruvate. 497. The kit according to any one of embodiments 482-485, wherein the nicotine salt comprises nicotine salicylate. 498. The kit according to any one of embodiments 482-485, characterized in that the nicotine salt comprises nicotine sorbate. 499. The kit according to any one of embodiments 482-485, characterized in that the nicotine salt comprises nicotine laurate. 500. The kit according to any one of embodiments 482-485, wherein the nicotine salt comprises nicotine levulinate. 501. The kit according to any one of embodiments 482-485, wherein the nicotine salt comprises nicotine benzoate. 502. The kit according to any one of embodiments 482-501, wherein the liquid carrier comprises glycerol, propylene glycol, trimethylene glycol, water, ethanol, or a combination thereof. 503. The kit according to any one of embodiments 482-501, wherein the liquid carrier comprises propylene glycol and vegetable glycerin. 504. The kit according to any one of embodiments 482-501, wherein the liquid carrier comprises 20% to 50% propylene glycol and 80% to 50% vegetable glycerin. 505. The kit according to any one of embodiments 482-501, wherein the liquid carrier comprises 30% propylene glycol and 70% vegetable glycerin. 506. The kit according to any one of embodiments 482-505, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 25% (w / w). 507. The kit according to any one of embodiments 482-505, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 20% (w / w). 508. The kit according to any one of embodiments 482-505, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 18% (w / w). 509. The kit according to any one of embodiments 482-505, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 15% (w / w). 510. The kit according to any one of embodiments 482-505, wherein the liquid formulation has a nicotine concentration of about 4% (w / w) to about 12% (w / w). 511. The kit according to any one of embodiments 482-505, wherein the liquid formulation has a nicotine concentration of about 4% (w / w). 512. The kit according to any one of embodiments 482-505, wherein the liquid formulation has a nicotine concentration of about 2% (w / w). 513. The kit according to any one of embodiments 482-512, characterized in that the liquid formulation further comprises a flavoring material. 514. The kit according to any one of embodiments 482-513, characterized in that the formulation is non-corrosive to electronic cigarettes. 515. The kit according to any one of embodiments 482-514, wherein the acid is stable at or below the operating temperature of about 200°C. 516. The kit according to any one of embodiments 482-515, wherein the acid does not decompose at the operating temperature or below about 200°C. 517. The kit according to any one of embodiments 482-516, wherein the acid does not oxidize at or below the operating temperature or about 200°C. 518. The kit according to any one of embodiments 482-517, characterized in that the formulation is non-corrosive to electronic cigarettes. 519. The kit according to any one of embodiments 482-518, characterized in that the formulation is non-toxic to users of electronic cigarettes. 520. The kit according to any one of embodiments 482-519, characterized in that it further comprises one or more additional nicotine salts in a biologically acceptable liquid carrier suitable for generating an inhalable aerosol upon heating. 521. The kit according to embodiment 520, wherein the second acid used to form the additional nicotine salt is selected from the group consisting of salicylic acid, sorbic acid, benzoic acid, pyruvic acid, lauric acid, and levulinic acid. 522. A cartridge including a fluid storage compartment, the fluid storage compartment storing a nicotine salt liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is characterized by a vapor pressure of greater than 20 mmHg at 200°C. 523. A cartridge including a fluid storage compartment, the fluid storage compartment storing a nicotine salt liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is characterized by a vapor pressure of about 20 to 200 mmHg at 200°C. 524. A cartridge including a fluid storage compartment, the fluid storage compartment storing a nicotine salt liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is further characterized by a melting point below 160°C, a boiling point above 160°C, and a difference of at least 50 degrees between the melting point and the boiling point. 525. A cartridge including a fluid storage compartment, the fluid storage compartment storing a nicotine salt liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is further characterized by a melting point at least 40 degrees below the operating temperature of the electronic cigarette, a boiling point no more than 40 degrees below the operating temperature of the electronic cigarette, and a difference of at least 50 degrees between the melting point and the boiling point. 526. The cartridge according to any one of embodiments 523-526, characterized in that the cartridge can be connected to an electronic cigarette. 527. The cartridge according to any one of embodiments 523-527, wherein the acid is a carboxylic acid. 528. The cartridge according to one of embodiments 523-527, characterized in that the acid used to form the nicotine salt is an organic acid. 529. The cartridge according to any one of embodiments 529, wherein the organic acid is a monocarboxylic acid, an aromatic acid, or a keto acid. 530. The cartridge according to embodiment 529, wherein the organic acid comprises formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, capric acid, citric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, phenylacetic acid, benzoic acid, pyruvic acid, levulinic acid, tartaric acid, lactic acid, malonic acid, succinic acid, fumaric acid, finic acid, gluconic acid, saccharic acid, salicylic acid, sorbic acid, malonic acid, or malic acid. 531. The cartridge according to any one of embodiments 523-527, wherein the acid used to form the nicotine salt is salicylic acid. 532. The cartridge according to any one of embodiments 523-527, wherein the acid used to form the nicotine salt is benzoic acid. 533. The cartridge according to any one of embodiments 523-527, wherein the acid used to form the nicotine salt is pyruvic acid. 534. The cartridge according to any one of embodiments 523-527, wherein the acid used to form the nicotine salt is sorbic acid. 535. The cartridge according to any one of embodiments 523-527, wherein the acid used to form the nicotine salt is lauric acid. 536. The cartridge according to any one of embodiments 523-527, wherein the acid used to form the nicotine salt is levulinic acid. 537. The cartridge according to any one of embodiments 523-527, characterized in that the nicotine salt comprises nicotine pyruvate. 538. The cartridge according to any one of embodiments 523-527, wherein the nicotine salt comprises nicotine salicylate. 539. The cartridge according to any one of embodiments 523-527, wherein the nicotine salt comprises nicotine sorbate. 540. The cartridge according to any one of embodiments 523-527, wherein the nicotine salt comprises nicotine laurate. 541. The cartridge according to any one of embodiments 523-527, characterized in that the nicotine salt comprises nicotine levulinate. 542. The cartridge according to any one of embodiments 523-527, wherein the nicotine salt comprises nicotine benzoate. 543. The cartridge according to any one of embodiments 523-543, wherein the liquid carrier comprises glycerol, propylene glycol, trimethylene glycol, water, ethanol, or a combination thereof. 544. The cartridge according to any one of embodiments 523-543, wherein the liquid carrier comprises propylene glycol and vegetable glycerin. 545. The cartridge according to any one of embodiments 523-543, wherein the liquid carrier comprises 20% to 50% propylene glycol and 80% to 50% vegetable glycerin. 546. The cartridge according to any one of embodiments 523-543, wherein the liquid carrier comprises 30% propylene glycol and 70% vegetable glycerin. 547. The cartridge of any one of embodiments 523-547, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 25% (w / w). 548. The cartridge according to any one of embodiments 523-547, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 20% (w / w). 549. The cartridge according to any one of embodiments 523-547, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 18% (w / w). 550. The cartridge of any one of embodiments 523-547, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 15% (w / w). 551. The cartridge according to any one of embodiments 523-547, wherein the liquid formulation has a nicotine concentration of about 4% (w / w) to about 12% (w / w). 552. The cartridge according to any one of embodiments 523-547, wherein the liquid formulation has a nicotine concentration of about 4% (w / w). 553. The cartridge according to any one of embodiments 523-547, wherein the liquid formulation has a nicotine concentration of about 2% (w / w). 554. The cartridge according to any one of embodiments 523-553, wherein the liquid formulation further comprises a flavoring material. 555. The cartridge according to any one of embodiments 523-554, wherein the formulation is non-corrosive to the electronic cigarette. 556. The cartridge according to any one of embodiments 523-555, wherein the acid is stable at or below the operating temperature of about 200°C. 557. The cartridge according to any one of embodiments 523-556, wherein the acid does not decompose at or below the operating temperature or about 200°C. 558. The cartridge according to any one of embodiments 523-557, wherein the acid does not oxidize at or below the operating temperature or about 200°C. 559. The cartridge according to any one of embodiments 523-558, wherein the formulation is non-corrosive to electronic cigarettes. 560. The cartridge according to any one of embodiments 523-559, characterized in that the formulation is non-toxic to users of electronic cigarettes. 561. The cartridge according to any one of embodiments 523-560, characterized in that it further comprises one or more additional nicotine salts in a biologically acceptable liquid carrier suitable for generating an inhalable aerosol upon heating. 562. The cartridge of embodiment 561 is characterized in that the second acid used to form the additional nicotine salt is selected from the group consisting of salicylic acid, sorbic acid, benzoic acid, pyruvic acid, lauric acid, and levulinic acid.

[0128] While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Many modifications, changes, and substitutions will occur to those skilled in the art without departing from the invention. It will be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is intended that the following embodiments define the scope of the invention, and that methods and structures within the scope of such embodiments and their equivalents are covered thereby.

Claims

1. 1. A method of delivering nicotine to a user, comprising: The method comprises: having a user activate an electronic cigarette, wherein the electronic cigarette contains a nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is characterized by a vapor pressure of greater than 20 mmHg at 200°C; and inhaling an aerosol produced from a nicotine salt formulation heated by an electronic cigarette.

2. 1. A method of delivering nicotine to a user, comprising: The method comprises: having a user activate an electronic cigarette, wherein the electronic cigarette contains a nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein the acid used to form the nicotine salt is characterized by a vapor pressure of 20 to 200 mmHg at 200°C; and inhaling an aerosol produced from a nicotine salt formulation heated by an electronic cigarette.

3. 1. A method of delivering nicotine to a user, comprising: The method comprises: activating an electronic cigarette, wherein the electronic cigarette contains a nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier, the acid used to form the nicotine salt being further characterized by a melting point below 160°C, a boiling point above 160°C, and a difference of at least 50 degrees between the melting point and the boiling point; and inhaling an aerosol produced from a nicotine salt formulation heated by an electronic cigarette.

4. 1. A method of delivering nicotine to a user, comprising: The method comprises: providing an electronic cigarette to a user, the electronic cigarette comprising a nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier, wherein an acid used to form the nicotine salt is further characterized by a melting point at least 40 degrees below the operating temperature of the electronic cigarette, a boiling point no more than 40 degrees below the operating temperature of the electronic cigarette, and a difference of at least 50 degrees between the melting point and the boiling point; inhaling an aerosol produced from a nicotine salt formulation heated by an electronic cigarette.

5. 4. The method according to claim 1, wherein the operating temperature is between 150°C and 250°C.

6. 4. The method according to claim 1, wherein the operating temperature is between 180°C and 220°C.

7. 4. The method according to claim 1, wherein the operating temperature is about 200°C.

8. 5. The method of claim 4, wherein the operating temperature is from 150°C to 250°C.

9. 5. The method of claim 4, wherein the operating temperature is from 180°C to 220°C.

10. 5. The method of claim 4, wherein the operating temperature is about 200°C.

11. 11. The method according to any one of claims 1 to 10, characterized in that the aerosol comprises a condensate of a nicotine salt.

12. 11. The method of any one of claims 1 to 10, wherein the aerosol comprises a condensate of free base nicotine.

13. 11. The method of any one of claims 1 to 10, wherein the aerosol comprises a condensate of free base nicotine and a condensate of a carrier.

14. 11. The method of any one of claims 1 to 10, wherein the aerosol comprises a condensate of free base nicotine and a condensate of an acid.

15. 15. The method of any one of claims 1-14, wherein the aerosol comprises condensate having a particle size of about 0.1 microns to about 5 microns.

16. 15. The method of any one of claims 1 to 14, wherein the aerosol comprises condensates having a particle size of about 0.1 microns to about 1 or 2 microns.

17. 15. The method of any one of claims 1-14, wherein the aerosol comprises condensate having a particle size of about 0.1 microns to about 0.7 microns.

18. 15. The method of any one of claims 1-14, wherein the aerosol comprises condensate having a particle size of about 0.3 microns to about 0.4 microns.

19. 19. The method according to any one of claims 1 to 18, characterized in that the acid is a carboxylic acid.

20. 19. The method of any one of claims 1 to 18, wherein the acid used to form the nicotine salt is an organic acid.

21. 21. The method of claim 20, wherein the organic acid is a monocarboxylic acid, an aromatic acid, or a keto acid.

22. 21. The method of claim 20, wherein the organic acid is formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, capric acid, citric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, phenylacetic acid, benzoic acid, pyruvic acid, levulinic acid, tartaric acid, lactic acid, malonic acid, succinic acid, fumaric acid, finic acid, gluconic acid, saccharic acid, salicylic acid, sorbic acid, malonic acid, or malic acid.

23. 19. The method according to any one of claims 1 to 18, characterized in that the acid used to form the nicotine salt is salicylic acid.

24. 19. The method according to any one of claims 1 to 18, characterized in that the acid used to form the nicotine salt is benzoic acid.

25. 19. The method according to any one of claims 1 to 18, characterized in that the acid used to form the nicotine salt is pyruvic acid.

26. 19. The method according to any one of claims 1 to 18, characterized in that the acid used to form the nicotine salt is sorbic acid.

27. 19. The method according to any one of claims 1 to 18, characterized in that the acid used to form the nicotine salt is lauric acid.

28. 19. The method of any one of claims 1 to 18, wherein the acid used to form the nicotine salt is levulinic acid.

29. 19. The method of any one of claims 1 to 18, wherein the nicotine salt comprises nicotine pyruvate.

30. 19. The method of any one of claims 1-18, wherein the nicotine salt comprises nicotine salicylate.

31. 19. The method of any one of claims 1 to 18, wherein the nicotine salt comprises nicotine sorbate.

32. 19. The method of any one of claims 1 to 18, wherein the nicotine salt comprises nicotine laurate.

33. 19. The method of any one of claims 1 to 18, wherein the nicotine salt comprises nicotine levulinate.

34. 19. The method of any one of claims 1 to 18, wherein the nicotine salt comprises nicotine benzoate.

35. 35. The method of any one of claims 1-34, wherein the liquid carrier comprises glycerol, propylene glycol, trimethylene glycol, water, ethanol, or a combination thereof.

36. 35. The method of any one of claims 1-34, wherein the liquid carrier comprises propylene glycol and vegetable glycerin.

37. 35. The method of any one of claims 1 to 34, wherein the liquid carrier comprises 20% to 50% of propylene glycol and 80% to 50% of vegetable glycerin.

38. 35. The method of any one of claims 1-34, wherein the liquid carrier comprises 30% propylene glycol and 70% vegetable glycerin.

39. 39. The method of any one of claims 1-38, wherein the nicotine salt is in an amount to form about 0.5% to about 20% of the nicotine in the inhalable aerosol.

40. 39. The method of any one of claims 1-38, wherein the nicotine salt is in an amount to form about 1% to about 20% of the nicotine in the inhalable aerosol.

41. 41. The method of any one of claims 1 to 40, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 25% (w / w).

42. 41. The method of any one of claims 1 to 40, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 20% (w / w).

43. 41. The method of any one of claims 1 to 40, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 18% (w / w).

44. 41. The method of any one of claims 1 to 40, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 15% (w / w).

45. 41. The method of any one of claims 1 to 40, wherein the liquid formulation has a nicotine concentration of about 4% (w / w) to about 12% (w / w).

46. 41. The method of any one of claims 1 to 40, wherein the liquid formulation has a nicotine concentration of about 4% (w / w).

47. 41. The method of any one of claims 1 to 40, wherein the liquid formulation has a nicotine concentration of about 2% (w / w).

48. 48. The method of any one of claims 1-47, wherein the formulation further comprises a flavoring material.

49. 49. The method of any one of claims 1-48, wherein the formulation is non-corrosive to the electronic cigarette.

50. 50. The method of any one of claims 1-49, wherein the acid is stable at or below the operating temperature of about 200°C.

51. 51. The method of any one of claims 1 to 50, wherein the acid does not decompose at or below the operating temperature or about 200°C.

52. 52. The method of any one of claims 1-51, wherein the acid does not oxidize at or below the operating temperature or about 200°C.

53. 53. The method according to any one of claims 1 to 52, wherein the formulation is non-corrosive to the electronic cigarette.

54. 54. The method of any one of claims 1-53, wherein the formulation is non-toxic to users of electronic cigarettes.

55. 55. The method of any one of claims 1-54, wherein the formulation further comprises one or more additional nicotine salts in a biologically acceptable liquid carrier suitable for generating an inhalable aerosol upon heating.

56. 56. The method of claim 55, wherein the second acid used to form the additional nicotine salt is selected from the group consisting of salicylic acid, sorbic acid, benzoic acid, pyruvic acid, lauric acid, and levulinic acid.

57. A nicotine salt liquid formulation in an electronic cigarette for producing an inhalable aerosol upon heating of the electronic cigarette, wherein the nicotine salt liquid formulation in the electronic cigarette comprises a nicotine salt in a biologically acceptable liquid carrier, and wherein an acid used to form the nicotine salt is characterized by a vapor pressure of greater than 20 mmHg at 200°C.

58. 1. A nicotine salt liquid formulation in an electronic cigarette for producing an inhalable aerosol upon heating of the electronic cigarette, wherein the nicotine salt liquid formulation in the electronic cigarette comprises a nicotine salt in a biologically acceptable liquid carrier, and wherein the acid used to form the nicotine salt is characterized by a vapor pressure of about 20 to 200 mmHg at 200°C.

59. 1. A nicotine salt liquid formulation in an electronic cigarette for producing an inhalable aerosol upon heating of the electronic cigarette, wherein the nicotine salt liquid formulation in the electronic cigarette comprises a nicotine salt in a biologically acceptable liquid carrier, and wherein an acid used to form the nicotine salt is further characterized by a melting point below 160°C, a boiling point above 160°C, and a difference of at least 50 degrees between the melting point and the boiling point.

60. 1. A nicotine salt liquid formulation in an electronic cigarette for producing an inhalable aerosol upon heating of the electronic cigarette, the nicotine salt liquid formulation in the electronic cigarette comprising a nicotine salt in a biologically acceptable liquid carrier, wherein an acid used to form the nicotine salt is further characterized by a melting point at least 40 degrees below the operating temperature of the electronic cigarette, a boiling point that is no more than 40 degrees below the operating temperature of the electronic cigarette, and a difference of at least 50 degrees between the melting point and the boiling point.

61. 60. A nicotine salt liquid formulation in an electronic cigarette according to any one of claims 57-59, characterized in that the electronic cigarette heats the nicotine salt formulation to an operating temperature of 150°C to 250°C.

62. 60. A nicotine salt liquid formulation in an electronic cigarette according to any one of claims 57-59, characterized in that the electronic cigarette heats the nicotine salt formulation to an operating temperature of between 180°C and 220°C.

63. 60. A nicotine salt liquid formulation in an electronic cigarette according to any one of claims 57-59, wherein the electronic cigarette heats the nicotine salt formulation to an operating temperature of about 200°C.

64. 61. The nicotine salt liquid formulation in an electronic cigarette according to claim 60, characterized in that the operating temperature is from 150°C to 250°C.

65. 61. The nicotine salt liquid formulation in an electronic cigarette according to claim 60, characterized in that the operating temperature is from 180°C to 220°C.

66. 61. The nicotine salt liquid formulation in an electronic cigarette of claim 60, characterized in that the operating temperature is about 200°C.

67. 67. The nicotine salt liquid formulation in an electronic cigarette according to claims 57-66, wherein the acid is a carboxylic acid.

68. 67. The nicotine salt liquid formulation in an electronic cigarette according to any one of claims 57-66, wherein the acid used to form the nicotine salt is an organic acid.

69. 69. The nicotine salt liquid formulation in an electronic cigarette of claim 68, wherein the organic acid is a monocarboxylic acid, an aromatic acid, or a keto acid.

70. 69. The nicotine salt liquid formulation in an electronic cigarette of claim 68, wherein the organic acid is formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, capric acid, citric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, phenylacetic acid, benzoic acid, pyruvic acid, levulinic acid, tartaric acid, lactic acid, malonic acid, succinic acid, fumaric acid, finic acid, gluconic acid, saccharic acid, salicylic acid, sorbic acid, malonic acid, or malic acid.

71. 67. The nicotine salt liquid formulation in an electronic cigarette according to any one of claims 57-66, wherein the acid used to form the nicotine salt is salicylic acid.

72. 67. The nicotine salt liquid formulation in an electronic cigarette according to any one of claims 57-66, wherein the acid used to form the nicotine salt is benzoic acid.

73. 67. The nicotine salt liquid formulation in an electronic cigarette according to any one of claims 57-66, wherein the acid used to form the nicotine salt is pyruvic acid.

74. 67. The nicotine salt liquid formulation in an electronic cigarette according to any one of claims 57-66, wherein the acid used to form the nicotine salt is sorbic acid.

75. 67. The nicotine salt liquid formulation in an electronic cigarette according to any one of claims 57-66, wherein the acid used to form the nicotine salt is lauric acid.

76. 67. The nicotine salt liquid formulation in an electronic cigarette according to any one of claims 57-66, wherein the acid used to form the nicotine salt is levulinic acid.

77. 67. The nicotine salt liquid formulation in an electronic cigarette according to any one of claims 57-66, wherein the nicotine salt comprises nicotine pyruvate.

78. 67. The nicotine salt liquid formulation in an electronic cigarette according to any one of claims 57-66, wherein the nicotine salt comprises nicotine salicylate.

79. 67. The nicotine salt liquid formulation in an electronic cigarette according to any one of claims 57-66, wherein the nicotine salt comprises nicotine sorbate.

80. 67. The nicotine salt liquid formulation in an electronic cigarette according to any one of claims 57-66, wherein the nicotine salt comprises nicotine laurate.

81. 67. The nicotine salt liquid formulation in an electronic cigarette according to any one of claims 57-66, wherein the nicotine salt comprises nicotine levulinate.

82. 67. The nicotine salt liquid formulation in an electronic cigarette according to any one of claims 57-66, wherein the nicotine salt comprises nicotine benzoate.

83. 83. The nicotine salt liquid formulation in an electronic cigarette of any one of claims 57-82, wherein the liquid carrier comprises glycerol, propylene glycol, trimethylene glycol, water, ethanol, or a combination thereof.

84. 83. The nicotine salt liquid formulation in an electronic cigarette according to any one of claims 57-82, wherein the liquid carrier comprises propylene glycol and vegetable glycerin.

85. 83. The nicotine salt liquid formulation in an electronic cigarette according to any one of claims 57-82, wherein the liquid carrier comprises 20% to 50% of propylene glycol and 80% to 50% of vegetable glycerin.

86. 83. The nicotine salt liquid formulation in an electronic cigarette according to any one of claims 57-82, wherein the liquid carrier comprises 30% propylene glycol and 70% vegetable glycerin.

87. 87. A nicotine salt liquid formulation in an electronic cigarette according to any one of claims 57-86, wherein the nicotine salt is in an amount that forms about 0.5% to about 20% of the nicotine in the inhalable aerosol.

88. 87. A nicotine salt liquid formulation in an electronic cigarette according to any one of claims 57-86, wherein the nicotine salt is in an amount that forms about 1% to about 20% of the nicotine in the inhalable aerosol.

89. 89. A nicotine salt liquid formulation in an electronic cigarette according to any one of claims 57-88, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 25% (w / w).

90. 90. A nicotine salt liquid formulation in an electronic cigarette according to any one of claims 57-89, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 20% (w / w).

91. 90. A nicotine salt liquid formulation in an electronic cigarette according to any one of claims 57-89, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 18% (w / w).

92. 90. A nicotine salt liquid formulation in an electronic cigarette according to any one of claims 57-89, wherein the liquid formulation has a nicotine concentration of about 1% (w / w) to about 15% (w / w).

93. 90. A nicotine salt liquid formulation in an electronic cigarette according to any one of claims 57-89, wherein the liquid formulation has a nicotine concentration of about 4% (w / w) to about 12% (w / w).

94. 90. A nicotine salt liquid formulation in an electronic cigarette according to any one of claims 57-89, wherein the liquid formulation has a nicotine concentration of about 4% (w / w).

95. 90. A nicotine salt liquid formulation in an electronic cigarette according to any one of claims 57-89, wherein the liquid formulation has a nicotine concentration of about 2% (w / w).

96. 96. A nicotine salt liquid formulation in an electronic cigarette according to any one of claims 57-95, characterized in that the liquid formulation further comprises a flavoring material.

97. 97. A nicotine salt liquid formulation in an electronic cigarette according to any one of claims 57-96, characterized in that the liquid formulation is non-corrosive to the electronic cigarette.

98. 98. The nicotine salt liquid formulation in an electronic cigarette according to any one of claims 57-97, wherein the acid is stable at or below the operating temperature of about 200°C.

99. 99. The nicotine salt liquid formulation in an electronic cigarette according to any one of claims 57-98, wherein the acid does not decompose at or below the operating temperature or about 200°C.

100. 100. The nicotine salt liquid formulation in an electronic cigarette according to any one of claims 57-99, wherein the acid does not oxidize at or below the operating temperature or about 200°C.

101. A nicotine salt liquid formulation in an electronic cigarette according to any one of claims 57-100, characterized in that the liquid formulation is non-corrosive to the electronic cigarette.

102. A nicotine salt liquid formulation in an electronic cigarette according to any one of claims 57-101, characterized in that the liquid formulation is non-toxic to users of the electronic cigarette.

103. 103. A nicotine salt liquid formulation in an electronic cigarette according to any one of claims 57-102, further comprising one or more additional nicotine salts in a biologically acceptable liquid carrier suitable for generating an inhalable aerosol upon heating.

104. 104. The nicotine salt liquid formulation in an electronic cigarette of claim 103, wherein the second acid used to form the additional nicotine salt is selected from the group consisting of salicylic acid, sorbic acid, benzoic acid, pyruvic acid, lauric acid, and levulinic acid.

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