Nicotine salt formulations for electronic cigarettes and method of delivering nicotine

Abstract

An electronic cigarette for generating an inhalable aerosol comprising: a liquid nicotine salt formulation comprising at least one nicotine salt, the at least one nicotine salt comprising a nicotine salt and benzoic acid in a biologically acceptable liquid carrier, where at least one nicotine salt in the liquid nicotine salt formulation is present in an amount that constitutes from 0.5% (w / w) to 20% (w / w) of nicotine in the inhalable aerosol; and The molar ratio of benzoic acid to nicotine in the liquid formulation of nicotine salt is 1:1.

Description

Nicotine salt formulations for electronic cigarettes and nicotine delivery method Technique cited US 2013 / 255702 A1 seeks to disclose a resistive heating element comprising: a substrate comprising an electrically conductive material and at least one carbonaceous additive, wherein the substrate or a part thereof is charred; and an aerosol precursor material associated with the charred substrate; wherein the resistive heating element has an electrical resistance of about 15 ohms or less. WO 2013 / 088230 A1 aims to disclose a plant-based composition for liquid to be vaporized in electronic cigarettes, comprising water and propylene glycol of plant origin and / or glycerol and / or nicotine and / or natural flavours. Summary of the invention An electronic cigarette and a method of delivering nicotine to a user are defined in the claims. Embodiments useful for understanding the invention are described below. Provided herein is a method of delivering nicotine to a user comprising operating an electronic cigarette to a user wherein the electronic cigarette comprises a nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein a acid used to form said nicotine salt is characterized by a vapor pressure >20 mmHg at 200°C, and inhaling an aerosol generated from the heated nicotine salt formulation by the electronic cigarette. Provided herein is a method of delivering nicotine to a user comprising operating an electronic cigarette to a user wherein the electronic cigarette comprises a nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein a acid used to form said nicotine salt is characterized by a vapor pressure of about 20 to 200 mmHg at 200°C, and inhaling an aerosol generated from the heated nicotine salt formulation by the electronic cigarette. Provided herein is a method of delivering nicotine to a user comprising operating an electronic cigarette wherein the electronic cigarette comprises a nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to forming said nicotine salt is further characterized by a melting point <160°C, a boiling point >160°C, and at least a 50 degree difference between the melting point and the boiling point, and inhaling an aerosol generated from the nicotine salt formulation heated by the electronic cigarette. Provided herein is a method of delivering nicotine to a user comprising providing an electronic cigarette to a user wherein the electronic cigarette comprises a nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein a acid used to form said nicotine salt is further characterized by a melting point at least 40 degrees lower than the operating temperature of the electronic cigarette, a boiling point not more than 40 degrees lower than the operating temperature of the electronic cigarette, and at least a 50 degree difference between the melting point and the boiling point, and inhaling an aerosol generated from the heated nicotine salt formulation by the electronic cigarette. Provided herein is a method of delivering nicotine to a user's blood, said method comprising providing an aerosol that the user inhales from an electronic cigarette comprising a nicotine salt formulation wherein providing the aerosol comprises the electronic cigarette comprising heats the formulation thereby generating the aerosol, wherein the aerosol is effective in delivering a user's blood level of nicotine that is at least 5 ng / ml at about 1.5 minutes after a first ten puff of the aerosol , each puff taken at 30-second intervals. Provided herein is a liquid nicotine salt formulation in an electronic cigarette for generating an inhalable aerosol upon heating in the electronic cigarette, the cigarette formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is characterized by a vapor pressure >20 mmHg at 200°C. Provided herein is a liquid nicotine salt formulation in an electronic cigarette for generating an inhalable aerosol upon heating in the electronic cigarette, the cigarette formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is characterized by a vapor pressure of about 20 to 200 mmHg at 200°C. Provided herein is a liquid nicotine salt formulation in an electronic cigarette for generating an inhalable aerosol upon heating in the electronic cigarette, the cigarette formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said icotine salt is further characterized by a melting point <1602C, a boiling point >1602C and a difference of at least 50 degrees between the melting point and the boiling point. Provided herein is a liquid nicotine salt formulation in an electronic cigarette for generating an inhalable aerosol upon heating in the electronic cigarette, the cigarette formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is further characterized by a melting point at least 40 degrees lower than the operating temperature of the electronic cigarette, a boiling point no more than 40 degrees lower than the operating temperature of the electronic cigarette, and at least a difference of 50 degrees between the melting point and the boiling point. Provided herein is a liquid nicotine salt formulation for generating an inhalable aerosol upon heating in the electronic cigarette, the liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is characterized by a vapor pressure >20 mmHg at 200°C. Provided herein is a liquid nicotine salt formulation for generating an inhalable aerosol upon heating in the electronic cigarette, the liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is characterized by a vapor pressure of about 20 to 200 mmHg at 200°C. Provided herein is a liquid nicotine salt formulation for generating an inhalable aerosol upon heating in the electronic cigarette, the liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is further characterized by a melting point <160°C, a boiling point >160°C, and at least a 50 degree difference between the melting point and the boiling point. Provided herein is a liquid nicotine salt formulation for generating an inhalable aerosol upon heating in the electronic cigarette, the liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is further characterized by a melting point at least 40 degrees lower than the operating temperature of the electronic cigarette, a boiling point not more than 40 degrees lower than the operating temperature of the electronic cigarette, and at least one difference 50 degrees between the melting point and the boiling point. Provided herein is a liquid nicotine salt formulation for use in an electronic cigarette, the liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is characterized by a vapor pressure >20 mmHg at 200°C. Provided herein is a liquid nicotine salt formulation for use in an electronic cigarette, the liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt it is characterized by a vapor pressure of about 20 to 200 mmHg at 200°C. Provided herein is a liquid nicotine salt formulation for use in an electronic cigarette, the liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt it is further characterized by a melting point <160°C, a boiling point >160°C, and at least a 50 degree difference between the melting point and the boiling point. Provided herein is a liquid nicotine salt formulation for use in an electronic cigarette, the liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is further characterized by a melting point at least 40 degrees lower than the operating temperature of the electronic cigarette, a boiling point not more than 40 degrees lower than the operating temperature of the electronic cigarette, and at least a 50 degree difference between the melting point and the boiling point. Provided herein is a 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 an acid used to form said nicotine salt is characterized by a vapor pressure >20 mmHg at 200°C, and the electronic cigarette heats the nicotine salt formulation to generate an aerosol inhalable by the user. Provided herein is a 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 an acid used to form said nicotine salt is characterized by a vapor pressure of about 20 to 200 mmHg at 200°C, and the electronic cigarette heats the nicotine salt formulation to generate an aerosol inhalable by the user. Provided herein is a 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 an acid used to form said nicotine salt is further characterized by a melting point <1602C, a boiling point >1602C, and at least a 50 degree difference between the melting point and the boiling point, and the electronic cigarette heats the nicotine salt formulation to generate an inhalable aerosol for the user. Provided herein is 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 that delivers a user's blood level of nicotine that is at least 5 ng / ml at about 1.5 minutes after a first ten puff of the aerosol, each puff taken at 30 second intervals. Provided herein is a use of a nicotine salt formulation for delivery of nicotine to a user from an electronic cigarette wherein the nicotine salt formulation comprises a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is further characterized by a melting point at least 40 degrees lower than the operating temperature of the electronic cigarette, a boiling point not more than 40 degrees lower than the operating temperature of the electronic cigarette, and at minus a 50 degree difference between the melting point and the boiling point, and the electronic cigarette heats the nicotine salt formulation to generate an aerosol inhalable by the user. There is provided herein a cartomizer for an electronic cigarette comprising: a liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is characterized by a vapor pressure of >20 mmHg at 200°C; an atomizer comprising a heating element in fluid communication with the liquid nicotine salt formulation; Y a fluid storage compartment that stores the liquid nicotine salt formulation. There is provided herein a cartomizer for an electronic cigarette comprising: a liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is characterized by a vapor pressure of from about 20 to 200 mmHg at 200°C; an atomizer comprising a heating element in fluid communication with the liquid nicotine salt formulation; Y a fluid storage compartment that stores the liquid nicotine salt formulation. There is provided herein a cartomizer for an electronic cigarette comprising: a liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is further characterized by a melting point <160°C, a boiling point >160° C and at least a 50°C degree difference between the melting point and the boiling point; an atomizer comprising a heating element in fluid communication with the liquid nicotine salt formulation; Y a fluid storage compartment that stores the liquid nicotine salt formulation. There is provided herein a cartomizer for an electronic cigarette comprising: a liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is further characterized by a melting point at least 40 degrees lower than the operating temperature of the cigarette electronic, a boiling point not more than 40 degrees lower than the operating temperature of the electronic cigarette, and at least a 50 degree difference between the melting point and the boiling point; an atomizer comprising a heating element in fluid communication with the liquid nicotine salt formulation; Y a fluid storage compartment that stores the liquid nicotine salt formulation. There is provided herein an electronic cigarette for generating an inhalable aerosol comprising: fluid storage compartment; a heater; Y a liquid nicotine salt formulation in the fluid storage compartment, the liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is characterized by a vapor pressure >20 mmHg at 200°C; A battery; Y a mouthpiece. An electronic cigarette for generating an inhalable aerosol is provided herein comprising: a fluid storage compartment; a heater; Y a liquid nicotine salt formulation in the fluid storage compartment, the liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is characterized by a vapor pressure of about 20 at 200mmHg at 2002C; A battery; Y a mouthpiece. An electronic cigarette for generating an inhalable aerosol is provided herein comprising: a fluid storage compartment; a heater; Y a liquid nicotine salt formulation in the fluid storage compartment, the liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is further characterized by a melting point <160 °C, a boiling point >160°C, and at least a 50 degree difference between the melting point and the boiling point; A battery; Y a mouthpiece. An electronic cigarette for generating an inhalable aerosol is provided herein comprising: a fluid storage compartment; a heater; Y a liquid nicotine salt formulation in the fluid storage compartment, the liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is further characterized by a melting point of at least 40 degrees lower than an electronic cigarette operating temperature, a boiling point not more than 40 degrees lower than the electronic cigarette operating temperature, and a difference of at least 50 degrees between the melting point and the boiling point; A battery; Y a mouthpiece. Provided herein is a cartridge in an electronic cigarette comprising a fluid storage compartment, wherein the fluid storage compartment stores a liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier in wherein an acid used to form said nicotine salt is characterized by a vapor pressure >20 mmHg at 200°C. Provided herein is a cartridge in an electronic cigarette comprising a fluid storage compartment, wherein the fluid storage compartment stores a liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier in wherein an acid used to form said nicotine salt is characterized by a vapor pressure of about 20 to 200 mmHg at 200°C. Provided herein is a cartridge in an electronic cigarette comprising a fluid storage compartment, wherein the fluid storage compartment stores a liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier in wherein an acid used to form said nicotine salt is further characterized by a melting point <1602C, a boiling point >160°C and at least a 50 degree difference between the melting point and the boiling point. Provided herein is a cartridge in an electronic cigarette comprising a fluid storage compartment, wherein the fluid storage compartment stores a liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier in wherein an acid used to form said nicotine salt is further characterized by a melting point at least 40 degrees lower than the operating temperature of the electronic cigarette, a boiling point not more than 40 degrees lower than the operating temperature of the electronic cigarette , and at least a 50 degree difference between the melting point and the boiling point. Provided herein is a kit comprising: (a) an electronic cigarette for generating an inhalable aerosol comprising Yo. a device body comprising a cartridge receptacle; ii. a cartridge comprising a fluid storage compartment, wherein the fluid storage compartment stores a liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt characterized by a vapor pressure >20 mmHg at 200°C; iii. a heater; IV. A battery; Y v. a mouthpiece; Y (b) instructions for using the electronic cigarette to generate an inhalable aerosol. Provided herein is a kit comprising: (a) an electronic cigarette for generating an inhalable aerosol comprising Yo. a device body comprising a cartridge receptacle; ii. a cartridge comprising a fluid storage compartment, wherein the fluid storage compartment stores a liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt it is characterized by a vapor pressure of about 20 to 200 mmHg at 200°C; iii. a heater; IV. A battery; Y v. a mouthpiece; Y (b) instructions for using the electronic cigarette to generate an inhalable aerosol. Provided herein is a kit comprising: (a) an electronic cigarette for generating an inhalable aerosol comprising Yo. a device body comprising a cartridge receptacle; ii. a cartridge comprising a fluid storage compartment, wherein the fluid storage compartment stores a liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt it is further characterized by a melting point <160°C, a boiling point >160°C and a difference of at least 50 degrees between the melting point and the boiling point; iii. a heater; IV. A battery; Y v. a mouthpiece; Y (b) instructions for using the electronic cigarette to generate an inhalable aerosol. Provided herein is a kit comprising: (a) an electronic cigarette for generating an inhalable aerosol comprising Yo. a device body comprising a cartridge receptacle; ii. a cartridge comprising a fluid storage compartment, wherein the fluid storage compartment stores a liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is further characterized by a melting point at least 40 degrees lower than the operating temperature of the electronic cigarette, a boiling point not more than 40 degrees lower than the operating temperature of the electronic cigarette, and at least a 50 degree difference between the melting point and the boiling point; iii. a heater; IV. A battery; Y v. a mouthpiece; Y (b) instructions for using the electronic cigarette to generate an inhalable aerosol. Brief description of the drawings A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description which sets forth illustrative embodiments, in which the principles of the invention are used, and the accompanying drawings of which: Figure 1 illustrates the results of heart rate data measured for six minutes from the start of the puffs. The Y axis is the heart rate (bpm) and the X axis represents the duration of the test (from -60 to 180 seconds); Figure 2 illustrates the results of heart rate data measured over ten minutes from the start of the puffs. The Y axis is the heart rate (bpm) and the X axis represents the duration of the test (from 0 to 10 minutes); Figure 3 illustrates the calculated vapor pressures of various acids relative to nicotine; Figure 4 illustrates the pharmacokinetic profiles of eight test articles in a blood plasma study; Figure 5 illustrates the comparison of Cmax and Tmax for eight test articles in a blood plasma study; Figure 6 illustrates the comparison of Cmax and AUC for eight test items in a blood plasma study; Figure 7 depicts an exemplary embodiment of an electronic cigarette having a fluid storage compartment comprising a nicotine salt formulation embodiment described herein; Y Figure 8 depicts an exemplary embodiment of an electronic cigarette cartomizer having a fluid storage compartment, a heater, and comprising a nicotine salt formulation embodiment described herein. Detailed description of the invention Nicotine is a chemical stimulant and increases heart rate and blood pressure when given to an individual or animal. The transfer of nicotine to an individual is associated with a feeling of physical and / or emotional satisfaction. Conflicting reports have been published regarding the transfer efficiency of nicotine free base compared to mono- or di-protonated nicotine salts. Studies on the transfer efficiency of nicotine free base and nicotine salts are complex and have yielded unpredictable results. Furthermore, such transfer efficiency studies have been performed under extremely high temperature conditions, comparable to smoking; therefore, they offer little guidance on the transfer efficiency of nicotine free base and nicotine salts under low temperature vaporization conditions. Some reports have postulated that nicotine free base should result in greater satisfaction in a user than any corresponding nicotine salt. It has been unexpectedly discovered herein that certain nicotine salt formulations provide greater satisfaction in an individual than nicotine free base, and more comparable to satisfaction in an individual smoking a traditional cigarette. The satisfaction effect is consistent with an efficient transfer of nicotine to the lungs of an individual and a rapid increase in plasma nicotine uptake as shown, by way of non-limiting example, in Example 8, at least. It has also been unexpectedly discovered herein that certain nicotine salt formulations provide greater satisfaction than other nicotine salt formulations, and such an effect has been demonstrated in the blood plasma levels of nicotine salt formulations exemplified herein. document, as a non-limiting example, in example 8, at least. These results show a difference in blood nicotine absorption rate that is higher for some nicotine salt formulations generated as an aerosol from an e-cigarette than for other nicotine salt formulations, and also higher than free base formulations. of nicotine, while the peak concentration of nicotine in the blood and the total amount of nicotine delivered appear comparable to a traditional cigarette and do not appear to vary significantly between the various nicotine formulations. Thus, nicotine salt formulations for use in an electronic cigarette, or the like, are described herein that provide an overall satisfying effect consistent with efficient transfer of nicotine to the lungs of an individual and a rapid increase of nicotine absorption in plasma. Therefore, provided herein are devices, nicotine salt formulation, systems, cartomizers, kits, and methods that are used to inhale an aerosol generated from a liquid nicotine salt formulation through the mouth or mouth. nose as described herein or as would be obvious to one skilled in the art upon reading the disclosure herein. Consistent with these satisfaction effects, it has been unexpectedly found herein that there is a difference between Cmax (peak concentration) and Tmax (time at which peak concentration is measured) when measuring blood plasma nicotine levels of nicotine formulations. nicotine free base inhaled using a low-temperature vaporizing device, i.e., an electronic cigarette, compared to the Cmax and Tmax (similarly measured of blood plasma nicotine levels) of a traditional cigarette. Also consistent with these satisfaction effects, it has been unexpectedly found herein that there is a difference between Cmax (peak concentration) and Tmax (time at which peak concentration is measured) when measuring blood plasma nicotine levels of formulations. of nicotine free base inhaled using a low-temperature vaporizing device, i.e., an electronic cigarette, compared to the Cmax and Tmax (similarly measuring blood plasma nicotine levels) of nicotine salt formulations inhaled using a low temperature vaporizing device, i.e. an electronic cigarette. Furthermore, it has been unexpectedly found that there is a difference between the plasma nicotine absorption rate of users inhaling nicotine free base formulations using a low temperature vaporizing device, i.e. an electronic cigarette, compared to the absorption rate of nicotine in the plasma of users who inhale the smoke of a traditional cigarette. Furthermore, it has been unexpectedly found that there is a difference between the plasma nicotine absorption rate of users inhaling nicotine free base formulations using a low temperature vaporizing device, i.e. an electronic cigarette, compared to the absorption rate of nicotine in the plasma of users inhaling nicotine salt formulations using a low-temperature vaporizing device, ie, an electronic cigarette. Therefore, when considering nicotine free base as the source of nicotine in compositions used in electronic cigarettes, the blood nicotine delivery of nicotine free base compositions when inhaled is not necessarily comparable in levels of nicotine. blood plasma (Cmax and Tmax) with respect to the delivery of nicotine from a traditional cigarette to the blood when inhaled. The blood delivery of nicotine from nicotine free base compositions when inhaled is not necessarily comparable at blood plasma levels (Cmax and Tmax) to the blood delivery of nicotine from nicotine salt formulations when inhaled. are inhaled. The blood delivery of nicotine from nicotine free base compositions when inhaled is not necessarily comparable to blood plasma levels when the rate of absorption of nicotine into the blood within the first 0-5 minutes is measured relative to to the delivery of nicotine from a traditional cigarette into the blood when inhaled. The delivery of nicotine from nicotine free base compositions to the blood when inhaled is not necessarily comparable to blood plasma levels when the rate of absorption of nicotine into the blood within the first 0-5 minutes is measured relative to to the delivery of nicotine from nicotine salt formulations to the blood when inhaled. Also consistent with these satisfaction effects, it has been unexpectedly found herein that, while there appear to be comparable Cmax and Tmax values ​​(measuring blood plasma nicotine levels) of nicotine salt formulations inhaled using a low-frequency vaporizing device. temperature, i.e. e-cigarette, compared to the Cmax and Tmax (similarly measuring blood plasma nicotine levels) of a traditional cigarette, there is a demonstrable difference between the plasma nicotine absorption rate of users who users inhaling certain nicotine salt formulations using a low-temperature vaping device, i.e. an e-cigarette, compared to the plasma nicotine absorption rate of users inhaling other nicotine salt formulations using a vaping device at low temperature, that is, an electronic cigarette. It is also unexpected that while the C max and T max values ​​are comparable to those of a traditional cigarette (or close to those of a traditional cigarette), the rate of absorption of nicotine into the blood plasma of users is higher in certain formulations. of nicotine salt than that of the traditional cigarette. Salt nicotine formulations demonstrating the fastest rate of nicotine absorption into plasma were more preferred in satisfaction assessments, and were rated more equivalent to cigarette satisfaction than salt nicotine formulations showing the slowest rates of increased nicotine in the blood plasma of the subjects. Furthermore, doubling the concentration of nicotine salt in the formulation may not necessarily affect the absorption rate of nicotine into the blood (see, as a non-limiting example, Example 8, nicotine benzoate tested at concentrations of 4% and 2%). Therefore, when looking at the nicotine salt formulations used in e-cigarettes, the nicotine salt formulations delivered via an e-cigarette appear comparable in C max and T max values ​​(measuring blood plasma nicotine levels). , however, not all nicotine salts behave similarly to each other or to a traditional cigarette with regard to the rate of absorption of nicotine into the blood in early periods of time (0-1.5 minutes) . These results are unexpected. Nicotine salt formulations made using acids that have a vapor pressure between 2.66 and 40 kPa (20-300 mmHg) at 200°C, or a vapor pressure >2.66 kPa (> 20 mmHg) at 200°C, or a vapor pressure of 2.66 to 26.6 kPa (20 to 200 mmHg) at 200°C, a vapor pressure of 2.66 to 40 kPa (20 to 300 mmHg) at 200 °C appears to have a higher rate of absorption of nicotine into the blood in earlier time periods (0-1.5 minutes, 0-3 minutes, 0-2 minutes, 0-4 minutes as a non-limiting example) than other formulations of nicotine. Salt nicotine, however, also provide satisfaction comparable to a traditional cigarette or closer to a traditional cigarette (compared to other nicotine salt formulations or compared to nicotine free base formulations). As a non-limiting example, 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 that have a difference between boiling point and melting point of at least 50°C, and a boiling point greater than 160°C and a melting point less than 160°C C appear to have a higher absorption rate of nicotine into the blood in early time periods (0-1.5 minutes, 0-3 minutes, 0-2 minutes, 0-4 minutes as a non-limiting example) than other salt formulations. of nicotine, however, they also provide satisfaction comparable to a traditional cigarette or closer to a traditional cigarette (compared to other nicotine salt formulations or compared to nicotine free base formulations). As a non-limiting example, 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 that have a difference between the boiling point and the melting point of at least 50°C, and a boiling point of not more than 40°C lower than the operating temperature, and a point melting temperatures at least 40°C lower than the operating temperature appear to have a higher absorption rate of nicotine into the blood in early time periods (0-1.5 minutes, 0-3 minutes, 0-2 minutes, 0- 4 minutes as a non-limiting example) than other nicotine salt formulations, however, they also provide satisfaction comparable to a traditional cigarette or closer to a traditional cigarette (compared to other nicotine salt formulations or compared to formulations of nicotine free base). The operating temperature can be from 100°C to 300°C, or from about 200°C, from about 150°C to about 250°C, from 180°C to 220°C, from about 180°C to about 220 °C, from 185°C to 215°C, from about 185°C to about 215°C, from about 190°C to about 210°C, from 190°C to 210°C, from 195°C to 205° C, or from about 1952C to about 205°C. As a non-limiting example, acids that meet the criteria in the preceding sentence include salicylic acid, sorbic acid, benzoic acid, pyruvic acid, lauric acid, and levulinic acid. Combinations of these criteria are contemplated herein for the preference of certain nicotine salt formulations. However, other reasons for excluding certain acids from formulations may not be related to the rate of nicotine absorption. For example, an acid may be inappropriate for use with the device materials (corrosive or otherwise incompatible). Sulfuric acid is an example of this, which may be inappropriate for the electronic cigarette device. An acid may be unsuitable for use by inhalation or for reasons of toxicity and therefore not compatible for human consumption, ingestion or inhalation. Again, sulfuric acid is an example of this, which may be inappropriate for a user of an electronic cigarette device, depending on the embodiment of the composition. An acid that is bitter or otherwise off flavor may also provide a reason for exclusion, such as acetic acid in some embodiments. Acids that oxidize at room temperature or operating temperature may be inappropriate for certain embodiments, eg, sorbic acid, as this indicates decomposition or reaction or instability which may be undesirable in the formulation. Decomposition of acids at room or operating temperature may also indicate that the acid is unsuitable for use in the formulations of embodiments. For example, citric acid decomposes at 175°C, and malic acid decomposes at 140°C, so for a device operating at 200°C these acids may not be appropriate. Acids that have poor solubility in the constituents of the composition may be inappropriate for use in certain embodiments of the compositions of the present invention. For example, nicotine bitartrate with a composition of nicotine and tartaric acid in a 1:2 molar ratio will not produce a solution at a concentration of 0.5% (w / w) nicotine or higher and 0.9% (p / p) of tartaric acid or higher in propylene glycol (PG) or vegetable glycerin (VG) or any mixture of Pg and VG under ambient conditions. As used herein, weight percent (w / w) refers to the weight of the individual component over the weight of the total formulation. As used in this specification and claims, the singular forms "a", "an" and "the" include plural referents unless the context clearly indicates otherwise. The term "organic acid" as used herein refers to an organic compound with acidic properties (eg, by the Bnansted-Lowry definition, or the Lewis definition). A common organic acid are carboxylic acids, whose acidity is associated with their carboxyl group -COOH. A dicarboxylic acid possesses two carboxylic acid groups. The relative acidity of an organic is measured by its pKa value, and one skilled in the art knows how to determine the acidity of an organic acid based on its given pKa value. The term "keto acid" as used herein refers to organic compounds 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 oxalacetic acid, which have the keto group adjacent to the carboxylic acid; beta-acetoacids, or 3-oxoacids, such as acetoacetic acid, having the ketone group on the second carbon from the carboxylic acid; gamma-ketoacids, or 4-oxoacids, such as levulinic acid, which have the ketone group at the third carbon from the carboxylic acid. The term "electronic cigarette" or "e-cigarette" or "low-temperature vaporizing device" as used herein, refers to an electronic inhaler that vaporizes a liquid solution into an aerosol mist, simulating the act of smoking tobacco. The liquid solution comprises a formulation comprising nicotine. There are many electronic cigarettes that are nothing like conventional cigarettes. The user can choose the amount of nicotine contained through inhalation. In general, an electronic cigarette contains three essential components: a plastic cartridge that serves as a mouthpiece and reservoir for liquid, an "atomizer" that vaporizes the liquid, and a battery. Other embodiments of electronic cigarettes include a combined atomizer and reservoir, called a "cartomizer" that may or may not be disposable, a mouthpiece that may or may not be integrated with the cartomizer, and a battery. As used in this specification and claims, unless otherwise indicated, the term "approximately" refers to variations of 1%, 2%, 3%, 4%, 5%, 10%, 15 % or 25%, depending on the realization. Suitable carriers (eg, a liquid solvent) for the nicotine salts described herein include a medium in which a nicotine salt is soluble under 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. The formulations described herein vary in their concentration. In some formulations, a dilute concentration of the nicotine salt is used in the carrier. In some formulations, a less dilute concentration of the nicotine salt is used in the carrier. In some formulations, the concentration of nicotine in the nicotine salt formulation is from about 1% (w / w) to about 25% (w / w). In some formulations, the concentration of nicotine in the nicotine salt formulation is from about 1% (w / w) to about 20% (w / w). In some formulations, the concentration of nicotine in the nicotine salt formulation is from about 1% (w / w) to about 18% (w / w). In some embodiments, the concentration of nicotine in the nicotine salt formulation is from about 1% (w / w) to about 15% (w / w). In some formulations, the concentration of nicotine in the nicotine salt formulation is from 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 nicotine concentration in the nicotine salt formulation is about 2% (w / w). In some formulations, the concentration of nicotine in the nicotine salt formulation is from 1% (w / w) to 25% (w / w). In some formulations, the concentration of nicotine in the nicotine salt formulation is from 1% (w / w) to 20% (w / w). In some formulations, the concentration of nicotine in the nicotine salt formulation is from 1% (w / w) to 18% (w / w). In some formulations, the concentration of nicotine in the nicotine salt formulation is from 1% (w / w) to 15% (w / w). In some formulations, the concentration of nicotine in the nicotine salt formulation is from 4% (w / w) to 12% (w / w). In some formulations, the nicotine concentration in the nicotine salt formulation is 4% (w / w). In some formulations, the nicotine concentration in the nicotine salt formulation is 2% (w / w). In some formulations, a less dilute concentration of one nicotine salt is used in conjunction with a more dilute concentration of a second nicotine salt. In some formulations, the nicotine concentration in the first nicotine salt formulation is from about 1% to about 20%, and is combined with a second nicotine salt formulation having a nicotine concentration therein of about 1% to about 20% or any range or concentration therein. In some formulations, the nicotine concentration in the first nicotine salt formulation is 1% to 20%, and is combined with a second nicotine salt formulation having a nicotine concentration therein of 1% to 20% or any range or concentration therein. As used with respect to nicotine concentrations in nicotine salt formulations, the term "about" refers to ranges of 0.05% (ie, if the concentration is about 2%, the range is from 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 (ie, if the concentration is about 4%, the range is 3%-5%), depending on the embodiment. Nicotine salts are formed by the addition of a suitable acid, including organic or inorganic acids. In some formulations provided herein, suitable organic acids are carboxylic acids. Examples of organic carboxylic acids described herein are monocarboxylic acids, dicarboxylic acids (organic acid containing two carboxylic acid groups), carboxylic acids containing an aromatic group such as benzoic acids, hydroxycarboxylic acids, heterocyclic carboxylic acids, terpenoid acids, sugar acids; such as pectic acids, amino acids, cycloaliphatic acids, aliphatic carboxylic acids, ketocarboxylic acids, and the like. In some formulations provided herein, the organic acids used herein are monocarboxylic acids. Nicotine salts are formed from the addition of a suitable acid to nicotine. In some formulations provided herein, the stoichiometric ratios of nicotine to acid (nicotine:acid) are 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 ratios of nicotine to acid are 1:1, 1:2, 1:3, or 1:4 (nicotine:acid). Nicotine is an alkaloid molecule comprising two basic nitrogens. It can occur in different states of protonation. For example, if there is no protonation, nicotine is called the "free base". If a nitrogen is protonated, then the nicotine would be "monoprotonated". Nicotine salt formulations can be formed by adding a suitable acid to nicotine, stirring the neat mixture at room temperature or 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 by the nicotine prior to dilution. Nicotine may not completely dissolve the proper acid prior to dilution. Adding the proper acid to nicotine to form a neat mixture can cause an exothermic reaction. The addition of the appropriate acid to nicotine to form a pure mixture can be carried out at 55°C. The addition of the appropriate acid to nicotine to form a pure mixture can be carried out at 90°C. The neat mixture can be cooled to room temperature before dilution. Dilution can be done at elevated temperature. 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 mixture of a suitable acid in a second carrier mixture. In some embodiments, the first and second carrier blends are identical in composition. In some embodiments, the first and second carrier blends are not identical in composition. In some embodiments, heating of the nicotine / acid / carrier mixture is required to facilitate complete dissolution. In some embodiments, nicotine salt formulations can be prepared and added to a 3:7 weight ratio solution of propylene glycol (PG) / vegetable glycerin (VG) and mixed thoroughly. While it is described herein that 10g of each of the formulations is produced, all of the procedures listed below are scalable. Other formulation forms may also be employed from the formulations indicated below, without departing from the disclosure herein, and as one skilled in the art will know from reading the disclosure herein. The optimum nicotine salt formulation can be determined by the vapor pressure of the constituent acid. In some embodiments, nicotine salt formulations comprise an acid with a vapor pressure that is similar to the vapor pressure of nicotine free base. In some embodiments, nicotine salt formulations are formed from an acid with a vapor pressure that is similar to the vapor pressure of nicotine free base 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 satisfaction in an individual user consistent with efficient transfer of nicotine and a rapid increase in plasma nicotine levels. This pattern may be due to the mechanism of action during heating of the nicotine salt formulation. The nicotine salt can dissociate at or just below the heating temperature of the device, resulting in a mixture of nicotine free base and the individual acid. At that point, if both the nicotine and acid have similar vapor pressures, they can be aerosolized at the same time, resulting in a transfer of both the nicotine free base and the constituent acid to the user. The liquid nicotine salt formulation for generating an inhalable aerosol upon heating in an electronic cigarette may comprise a nicotine salt in a biologically acceptable liquid carrier; wherein the acid used to form said nicotine salt is characterized by a vapor pressure of between 2.66 and 533.3 kPa (20-4000 mmHg) at 200°C. In some embodiments, the acid used to form the nicotine salt is characterized by a vapor pressure between 2.66 and 266.6 kPa (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 13.3 and 40 kPa (100-300 mmHg) at 200°C. Unexpectedly, different nicotine salt formulations produced varying degrees of satisfaction in one individual. In some embodiments, the degree of protonation of the nicotine salt affected satisfaction, such that more protonation was less satisfying compared to less protonation. The nicotine salt formed can be monoprotonated. The nicotine salt formed can be diprotonated. The nicotine salt may exist in more than one protonation state, eg, an equilibrium of 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-forming reaction. The degree of protonation of the nicotine molecule can depend on the solvent. The degree of protonation of the nicotine molecule may be unknown. In some embodiments, monoprotonated nicotine salts produced a high degree of user satisfaction. For example, nicotine benzoate and nicotine salicylate are monoprotonated nicotine salts and all produce a high degree of user satisfaction. The reason for this trend can be explained by a mechanism of action where nicotine is first deprotonated before being vaporized with the constituent acid and then retained and stabilized after being re-protonated by acid going downstream to the lungs of the patient. Username. It may be easier to remove one proton versus two protons, resulting in better transfer efficiency. Furthermore, the lack of satisfaction from nicotine free base indicates that a second factor may be important. A nicotine salt may perform best when it is at its optimum degree of protonation, depending on the salt. For example, nicotine pyruvate is a nicotine salt with a nicotine:acid ratio of 1:2. The formulation containing nicotine pyruvate (1:2) can provide more satisfaction to the user than the one containing the same amount of nicotine but only half the amount of pyruvic acid, ie nicotine pyruvate (1:1). This can be explained because 1 mole of nicotine produces a salt with 2 moles of pyruvic acid. When there is not enough pyruvic acid to associate with all of the nicotine molecules, the remaining unprotonated nicotine free base in the formulation can reduce the satisfaction provided by the formulation. The aroma of the constituent acid used in the formation of the salts may be a consideration in choosing the acid. A suitable acid may have little or no toxicity to humans at the concentrations used. A suitable acid may be compatible with the components of the electronic cigarette with which it comes into contact or could come into contact at the concentrations used. That is, said acid does not degrade or otherwise react with the components of the electronic cigarette with which it comes into contact or could come into contact. The odor of the constituent acid used in the formation of the salts may be a consideration in choosing a suitable acid. The concentration of the nicotine salt in the carrier can affect individual user satisfaction. In some embodiments, the flavor of the formulation is adjusted by changing the acid. In some embodiments, the flavor of the formulation is adjusted by adding exogenous flavors. In some embodiments, an off-tasting or off-odour acid is used in minute amounts to mitigate such characteristics. In some embodiments, an exogenous acid with a pleasant odor or flavor is added to the formulation. Examples of salts that can provide flavor and aroma to the main spray at certain levels include nicotine acetate, nicotine oxalate, nicotine malate, nicotine isovalerate, nicotine lactate, nicotine citrate, nicotine phenylacetate and nicotine myristate. Nicotine salt formulations can generate an inhalable aerosol when heated in an electronic cigarette. The amount of nicotine aerosol or nicotine salt inhaled can be determined by the user. The user can, for example, modify the amount of nicotine or nicotine salt inhaled by adjusting their inhalation force. Formulations comprising two or more nicotine salts are described herein. In some embodiments, where a formulation comprises two or more nicotine salts, each individual nicotine salt is formed as described herein. Nicotine salt formulations, as used herein, refer to single or mixtures of nicotine salts with other suitable chemical components used for electronic cigarettes, such as carriers, stabilizers, diluents, dispersing agents, suspension, thickening agents and / or excipients. In certain embodiments, the nicotine salt formulation is stirred at ambient conditions for 20 minutes. In certain embodiments, the nicotine salt formulation is heated and stirred at 55C for 20 minutes. In certain embodiments, the nicotine salt formulation is heated and stirred at 90C for 60 minutes. In certain embodiments, the formulation facilitates delivery of nicotine to an organism (eg, lung). The nicotine in the nicotine salt formulations provided herein is either naturally occurring nicotine (eg, from extract of nicotinic species such as tobacco), or synthetic nicotine. In some embodiments, the nicotine is (-)-nicotine, (+)-nicotine, or a mixture thereof. In some embodiments, the nicotine is used in a relatively pure form (eg, greater than about 80% pure, 85% pure, 90% pure, 95% pure, or 99% pure). In some embodiments, the nicotine for the nicotine salt formulation provided herein has a "water clear" appearance to prevent or minimize the formation of tarry residue during subsequent steps of salt formation. The nicotine salt formulations used for the electronic cigarettes described herein, in some embodiments, have a nicotine concentration of from about 0.5% (w / w) to about 20% (w / w), in where the concentration is the weight of nicotine with respect to the total weight of the solution, that is, (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of from about 1% (w / w) to about 20% (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of from about 1% (w / w) to about 18% (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of from about 1% (w / w) to about 15% (w / w). In certain embodiments, the nicotine al formulations provided herein have a nicotine concentration of from about 4% (w / w) to about 12% (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of from about 1% (w / w) to about 18% (w / w), from about 3% (w / w). ) to about 15% (w / w), or from about 4% (w / w) to about 12% (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of from about 0.5% (w / w) to about 10% (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of from about 0.5% (w / w) to about 5% (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of from about 0.5% (w / w) to about 4% (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of from about 0.5% (w / w) to about 3% (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of from about 0.5% (w / w) to about 2% (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of from about 0.5% (w / w) to about 1% (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of from about 1% (w / w) to about 10% (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of from about 1% (w / w) to about 5% (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of from about 1% (w / w) to about 4% (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of from about 1% (w / w) to about 3% (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of from about 1% (w / w) to about 2% (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of from about 2% (w / w) to about 10% (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of from about 2% (w / w) to about 5% (w / w). In certain embodiments, the nicotine salt formulations provided herein have a nicotine concentration of from about 2% (w / w) to about 4% (w / w).Certain embodiments provide a nicotine salt formulation having 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, 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% (p / p), or more, including any increase therein. Certain embodiments provide a nicotine salt formulation having a nicotine concentration of about 5% (w / w). Certain embodiments provide a nicotine salt formulation having a nicotine concentration of about 4% (w / w). Certain embodiments provide a nicotine salt formulation having a nicotine concentration of about 3% (w / w). Certain embodiments provide a nicotine salt formulation having a nicotine concentration of about 2% (w / w). Certain embodiments provide a nicotine salt formulation having a nicotine concentration of about 1% (w / w). Certain embodiments provide a nicotine salt formulation having a nicotine concentration of about 0.5% (w / w). The formulation may further comprise one or more flavoring agents. The acid suitable for the nicotine salt formulation can have a vapor pressure of >2.66 kPa (>20 mmHg) at 200°C and is non-corrosive to the electronic cigarette and non-toxic to humans. In some embodiments, the acid suitable for nicotine salt formation is selected from the group consisting of salicylic acid, formic acid, sorbic acid, acetic acid, benzoic acid, pyruvic acid, lauric acid, and levulinic acid. The acid suitable for nicotine salt formulation can have a vapor pressure of about 2.66 to 26.6 kPa (20 to 200 mmHg) at 200°C and is non-corrosive to e-cigarette and non-toxic to humans. . In some embodiments, the acid suitable for nicotine salt formation is selected from the group consisting of salicylic acid, benzoic acid, lauric acid, and levulinic acid. Suitable acid for nicotine salt formulation can have melting point <160°C, boiling point >160°C, at least 50 degree difference between melting point and boiling point, and not it is not corrosive to electronic cigarette nor is it toxic to human beings. In some embodiments, the acid suitable for the formation of nicotine salts has a melting point at least 40 degrees lower than the operating temperature of the electronic cigarette, a boiling point not more than 40 degrees lower than the operating temperature of the electronic cigarette e-cigarette, at least 50 degree difference between melting point and boiling point, and not corrosive to e-cigarette and not toxic to human; where the operating temperature is 200°C. In some embodiments, the acid suitable for the formation of nicotine salts is selected from the group consisting of salicylic acid, sorbic acid, benzoic acid, pyruvic acid, lauric acid, and levulinic acid. The acid suitable for the nicotine salt formulation does not decompose at the operating temperature of the electronic cigarette. In some embodiments, the acid suitable for the formation of nicotine salts does not oxidize at the operating temperature of the electronic cigarette. In some embodiments, the acid suitable for the formation of nicotine salts is not oxidized at room temperature. In some embodiments, the acid suitable for nicotine salt formation does not provide an unpleasant taste. In some embodiments, the acid suitable for the formation of nicotine salts has good solubility in a liquid formulation for use in an electronic cigarette. Provided herein is an electronic cigarette 2 having a fluid storage compartment 4 comprising an embodiment of a nicotine salt formulation of any embodiment described herein within the fluid storage compartment described herein. . One embodiment is shown in Figure 7. The electronic cigarette 2 of Figure 7 includes a muzzle end 6 and a charging end 8. The muzzle end 6 includes a mouthpiece 10. The charging end 8 may be connected to a battery. or to a charger or both, wherein the battery is inside a body of the electronic cigarette, and the charger is separate from the battery and is attached to the body or the battery to charge the battery. In some embodiments, the electronic cigarette comprises a rechargeable battery within a body 14 of the electronic cigarette and the charging end 8 comprises a connection 12 for charging the rechargeable battery. In some embodiments, the electronic cigarette comprises a cartomizer comprising the fluid storage compartment and an atomizer. In some embodiments, the atomizer comprises a heater. In some embodiments, fluid storage compartment 4 may be separate from an atomizer. In some embodiments, the fluid storage compartment 4 may be replaced as part of a replaceable cartridge. In some embodiments, the fluid storage compartment 4 may be refilled. In some embodiments, the nozzle 10 is replaceable. Provided herein is a cartomizer 18 for an electronic cigarette 2 having a fluid storage compartment 4 comprising an embodiment of a nicotine salt formulation of any embodiment described herein within the described fluid storage compartment. in the present document. The FIG. 8 embodiment of cartomizer 18 includes a muzzle end 6, and a connection end 16. The connection end 16 in the FIG. 8 embodiment attaches the cartomizer 14 to the body of an electronic cigarette, or to an electronic cigarette battery. electronic cigarette, or both. The muzzle end 6 includes a mouthpiece 10. In some embodiments, the cartomizer does not include a mouthpiece, and in such embodiments, the cartomizer may be attached to an electronic cigarette mouthpiece, or the cartomizer may be attached to a battery or body of an electronic cigarette. electronic cigarette, while the mouthpiece also attaches 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 comprises the fluid storage compartment 4 and an atomizer (not shown). In some embodiments, the atomizer comprises a heater (not shown). examples Example 1: Preparation of nicotine salt formulations Various nicotine formulations were prepared and added to a 3:7 weight ratio solution of propylene glycol (PG) / vegetable glycerin (VG) and mixed thoroughly. The examples shown below were used to prepare 10 g of each of the formulations. All procedures are scalable. For example, in order to make nicotine formulations with a final nicotine free base equivalent concentration of 2% (w / w), the following procedures were applied to each individual formulation. - Nicotine benzoate salt formulation: 0.15 g of benzoic acid was added to a beaker followed by the addition of 0.2 g of nicotine to the same beaker. The mixture was stirred at 55°C for 20 minutes until the benzoic acid completely dissolved and an orange oily mixture was formed. The mixture was cooled to ambient conditions. 9.65 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 achieved. - A nicotine benzoate salt formulation can also be prepared by adding 0.15 g benzoic acid to a beaker followed by the addition of 0.2 g nicotine and 9.65 g PG / VG solution (3: 7) to the same beaker. The mixture was then stirred at 55°C for 20 minutes until a visually homogeneous formulation solution without undissolved chemicals was achieved. - A nicotine citrate salt formulation was made by adding 0.47 g of citric acid to a beaker followed by the addition of 0.2 g of nicotine and 9.33 g of PG / VG solution (3:7 ) to the same beaker. The mixture was then stirred at 90°C for 60 minutes until a visually homogeneous formulation solution without undissolved chemicals was achieved. - A nicotine malate salt formulation was made by adding 0.33 g L-malic acid to a beaker followed by the addition of 0.2 g nicotine and 9.47 g PG / VG solution (3 :7) to the same beaker. The mixture was then stirred at 90°C for 60 minutes until a visually homogeneous formulation solution without undissolved chemicals was achieved. - A nicotine succinate salt formulation was made by adding 0.29 g of succinic acid to a beaker followed by the addition of 0.2 g of nicotine and 9.51 g of PG / VG solution (3:7 ) to the same beaker. The mixture was then stirred at 90°C for 60 minutes until a visually homogeneous formulation solution without undissolved chemicals was achieved. - A nicotine salicylate salt formulation was made by adding 0.17 g salicylic acid to a beaker followed by the addition of 0.2 g nicotine and 9.63 g PG / VG solution (3:7 ) to the same beaker. The mixture was then stirred at 90°C for 60 minutes until a visually homogeneous formulation solution without undissolved chemicals was achieved. - A nicotine salicylate salt formulation can also be made by adding 0.17 g salicylic acid to a beaker followed by 0.2 g nicotine to the same beaker. The mixture was stirred at 90°C for 60 minutes until the salicylic acid completely dissolved and an orange oily mixture was formed. The mixture was either cooled to room conditions or kept 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 with no undissolved chemicals was achieved. - A nicotine free base formulation was made by adding 0.2 g of nicotine to a beaker followed by the addition of 9.8 g of PG / VG (3:7) solution to the same beaker. The mixture was then stirred at ambient conditions for 10 minutes until a visually homogeneous formulation solution was achieved. For example, to make nicotine salt formulations with a final nicotine free base equivalent concentration of 3% (w / w), the following procedures were applied to each individual formulation. - Nicotine benzoate salt formulation: 0.23 g of benzoic acid was added to a beaker followed by the addition of 0.3 g of nicotine to the same beaker. The mixture was stirred at 55°C for 20 minutes until the benzoic acid 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 stirred until a visually homogeneous formulation solution was achieved. - A nicotine benzoate salt formulation can also be prepared by adding 0.23 g benzoic acid to a beaker followed by the addition of 0.3 g nicotine and 9.47 g PG / VG solution (3: 7) to the same beaker. The mixture was then stirred at 55°C for 20 minutes until a visually homogeneous formulation solution without undissolved chemicals was achieved. - A nicotine citrate salt formulation was made by adding 0.71 g of citric acid to a beaker followed by the addition of 0.3 g of nicotine and 8.99 g of PG / VG solution (3:7 ) to the same beaker. The mixture was then stirred at 90°C for 60 minutes until a visually homogeneous formulation solution without undissolved chemicals was achieved. - A nicotine malate salt formulation was made by adding 0.5 g L-malic acid to a beaker followed by the addition of 0.3 g nicotine and 9.2 g PG / VG solution (3 :7) to the same beaker. The mixture was then stirred at 90°C for 60 minutes until a visually homogeneous formulation solution without undissolved chemicals was achieved. - A nicotine levulinate salt formulation was made by adding 0.64 g of molten levulinic acid to a beaker followed by the addition of 0.3 g of nicotine to the same beaker. The mixture was stirred at ambient conditions for 10 minutes. An exothermic reaction took place and an oily product was produced. The mixture was allowed to cool to room temperature and 9.06 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 achieved. - A nicotine pyruvate salt formulation was made by adding 0.33 g of pyruvic acid to a beaker followed by the addition of 0.3 g of nicotine to the same beaker. The mixture was stirred at ambient conditions for 10 minutes. An exothermic reaction took place and an oily product was produced. The mixture was allowed to cool to room 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 achieved. - A nicotine succinate salt formulation was made by adding 0.44 g of succinic acid to a beaker followed by the addition of 0.3 g of nicotine and 9.26 g of PG / VG solution (3:7 ) to the same beaker. The mixture was then stirred at 90°C for 60 minutes until a visually homogeneous formulation solution without undissolved chemicals was achieved. - A nicotine salicylate salt formulation was made by adding 0.26 g salicylic acid to a beaker followed by the addition of 0.3 g nicotine and 9.44 g PG / VG solution (3:7 ) to the same beaker. The mixture was then stirred at 90°C for 60 minutes until a visually homogeneous formulation solution without undissolved chemicals was achieved. - A nicotine salicylate salt formulation can also be made by adding 0.26 g of salicylic acid to a beaker followed by the addition of 0.3 g of nicotine to the same beaker. The mixture was stirred at 90°C for 60 minutes until the salicylic acid completely dissolved and an orange oily mixture was formed. The mixture was either cooled to room conditions or kept 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 with no undissolved chemicals was achieved. - A nicotine free base formulation was made by adding 0.3 g of nicotine to a beaker followed by the addition of 9.7 g of PG / VG (3:7) solution to the same beaker. The mixture was then stirred at ambient conditions for 10 minutes until a visually homogeneous formulation solution was achieved. For example, to make nicotine salt formulations with a final nicotine free base equivalent concentration of 4% (w / w), the following procedures were applied to each individual formulation. - Nicotine benzoate salt formulation: 0.3 g of benzoic acid was added to a beaker followed by the addition of 0.4 g of nicotine to the same beaker. The mixture was stirred at 55°C for 20 minutes until the benzoic acid 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 stirred until a visually homogeneous formulation solution was achieved. - A nicotine benzoate salt formulation can also be made by adding 0.3 g benzoic acid to a beaker followed by the addition of 0.4 g nicotine and 9.7 g PG / VG solution (3: 7) to the same beaker. The mixture was then stirred at 55°C for 20 minutes until a visually homogeneous formulation solution without undissolved chemicals was achieved. For example, to make nicotine salt formulations with a final nicotine free base equivalent concentration of 5% (w / w), the following procedures were applied to each individual formulation. - Nicotine benzoate salt formulation: 0.38 g of benzoic acid was added to a beaker followed by the addition of 0.5 g of nicotine to the same beaker. The mixture was stirred at 55°C for 20 minutes until the benzoic acid 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 stirred until a visually homogeneous formulation solution was achieved. - A nicotine benzoate salt formulation can also be made by adding 0.38 g benzoic acid to a beaker followed by the addition of 0.5 g nicotine and 9.12 g PG / VG solution (3: 7) to the same beaker. The mixture was then stirred at 55°C for 20 minutes until a visually homogeneous formulation solution without undissolved chemicals was achieved. - A nicotine malate salt formulation was made by adding 0.83 g L-malic acid to a beaker followed by the addition of 0.5 g nicotine and 8.67 g PG / VG solution (3 :7) to the same beaker. The mixture was then stirred at 90°C for 60 minutes until a visually homogeneous formulation solution without undissolved chemicals was achieved. - A nicotine levulinate salt formulation was made by adding 1.07 g of molten levulinic acid to a beaker followed by the addition of 0.5 g of nicotine to the same beaker. The mixture was stirred at ambient conditions for 10 minutes. An exothermic reaction took place and an oily product was produced. The mixture was allowed to cool to room temperature and 8.43 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 achieved. - A nicotine pyruvate salt formulation was made by adding 0.54 g of pyruvic acid to a beaker followed by the addition of 0.5 g of nicotine to the same beaker. The mixture was stirred at ambient conditions for 10 minutes. An exothermic reaction took place and an oily product was produced. The mixture was allowed to cool to room temperature and 8.96 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 achieved. - A nicotine succinate salt formulation was made by adding 0.73 g of succinic acid to a beaker followed by the addition of 0.5 g of nicotine and 8.77 g of PG / VG solution (3:7 ) to the same beaker. The mixture was then stirred at 90°C for 60 minutes until a visually homogeneous formulation solution without undissolved chemicals was achieved. - A nicotine salicylate salt formulation was made by adding 0.43 g salicylic acid to a beaker followed by the addition of 0.5 g nicotine and 9.07 g PG / VG solution (3:7 ) to the same beaker. The mixture was then stirred at 90°C for 60 minutes until a visually homogeneous formulation solution without undissolved chemicals was achieved. - A nicotine salicylate salt formulation can also be made by adding 0.43 g salicylic acid to a beaker followed by 0.5 g nicotine to the same beaker. The mixture was stirred at 90°C for 60 minutes until the salicylic acid completely dissolved and an orange oily mixture was formed. The mixture was either cooled to room conditions or kept at 90C 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 with no undissolved chemicals was achieved. - A nicotine free base formulation was made by adding 0.5 g of nicotine to a beaker followed by the addition of 9.5 g of PG / VG (3:7) solution to the same beaker. The mixture was then stirred at ambient conditions for 10 minutes until a visually homogeneous formulation solution was achieved. Various formulations comprising different nicotine salts may be similarly prepared, or different concentrations of the above nicotine formulations or other nicotine salt formulations may be prepared as one skilled in the art would know from reading the disclosure herein. Various formulations comprising two or more nicotine salts in a 3:7 ratio solution of propylene glycol (PG) / vegetable glycerin (VG) can be similarly prepared. 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 achieve 5% w / w of nicotine formulation. Another formulation is also provided by way of example. For example, add 0.23 g (1.33% w / w nicotine) of nicotine benzoate salt (1:1 molar ratio nicotine / benzoic acid), 0.25 g (1.33% w / p of nicotine) of nicotine salicylate salt (1:1 molar ratio of nicotine / salicylic acid) and 0.28 g (1.34% w / w of nicotine) of nicotine pyruvate salt (1:2 molar ratio of nicotine / pyruvic acid) to 9.25 g of PG / VG solution, to achieve 5% w / w nicotine formulation. Example 2: Study of the heart rate of nicotine solutions through an electronic cigarette Exemplary 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 as outlined in Example 1 in 3% w / w solutions and administered in the same way by electronic cigarette to the same human subject. Approximately 0.5 mL of each solution was loaded into an "eRoll" cartridge atomizer (joyetech.com) for use in the study. Then the atomizer was attached to an electronic cigarette "eRoll" (same manufacturer) . The operating temperature was from about 150°C to about 250°C, or from about 180°C to about 220°C. Heart rate measurements were taken for 6 minutes; from 1 minute before the start of the puffs, for 3 minutes during the puffs, and continuing until 2 minutes after the end of the puffs. The test participant took 10 puffs over 3 minutes in each case. Baseline heart rate was the average heart rate over the first minute before puffs began. Heart rate after puffs began was averaged over 20-second intervals. The puff (inhalation) occurred every 20 seconds for a total of 3 minutes. Normalized heart rate was defined as the ratio of the individual heart rate data point to the base heart rate. Final results were presented as normalized heart rate, shown for the first 4 minutes in Figure 1. Figure 1 summarizes the results of heart rate measurements taken for a variety of nicotine salt formulations. For ease of reference when reviewing Figure 1, at the 180 second time point, from top to bottom (highest normalized heart rate to lowest normalized heart rate), the nicotine formulations are as follows: nicotine salicylate formulation nicotine, nicotine malate formulation, nicotine levulinate formulation (nearly identical to nicotine malate formulation at 180 seconds, so as a second benchmark: nicotine malate formulation curve is lower than the nicotine levulinate formulation curve at the 160 second time point), nicotine pyruvate formulation, nicotine benzoate formulation, nicotine citrate formulation, nicotine succinate formulation, and nicotine free base formulation. The lower curve (lowest normalized heart rate) at the 180 second time point is associated with placebo (100% propylene glycol). Test formulations comprising a nicotine salt cause a faster and more significant increase in heart rate than placebo. Test formulations comprising a nicotine salt also cause a faster and more significant rise compared to a nicotine free base formulation with the same amount of nicotine by weight. Furthermore, nicotine salts (for example, nicotine benzoate and nicotine pyruvate) prepared from acids having calculated vapor pressures between 20-200 mmHg at 200°C (benzoic acid (171.66 mmHg), with the exception of pyruvic acid (which has a boiling point of 165C), respectively) cause a more rapid increase in heart rate than the rest. Nicotine salts (for example, nicotine levulinate, nicotine benzoate, and nicotine salicylate) prepared from the acids (benzoic acid, levulinic acid, and salicylic acid, respectively) also cause a more significant increase in heart rate. Therefore, other suitable nicotine salts formed from the acids with the similar vapor pressure and / or boiling point may be used in accordance with the practice of the present invention. This experience of increased heart rate theoretically approximating or theoretically comparable to that of a traditional burnt cigarette has not been demonstrated or identified in other e-cigarette devices. Low-temperature tobacco vaporization devices (e-cigarettes) have also not been shown or identified to not burn tobacco, even when a nicotine salt (a 20% (w / w) or greater solution of nicotine salt was used). ) as a tobacco additive. Therefore, the results of this experiment are surprising and unexpected. Example 3: Satisfaction study of nicotine salt solution through an electronic cigarette In addition to the heart rate study shown in Example 2, nicotine formulations (using 3% w / w nicotine formulations as described in Example 1) were used to conduct a satisfaction study in a single participant of Test. The test participant, an e-cigarette and / or traditional cigarette user, was required to be nicotine-free for at least 12 hours prior to testing. The participant took 10 puffs using an electronic cigarette (the same one used in Example 2) over 3 minutes in each case, and was then asked to rate the level of physical and emotional satisfaction they felt on a scale of 0 - 10, with 0 being no physical or emotional satisfaction. The results indicated that the least satisfactory compound was nicotine free base. Nicotine benzoate, nicotine salicylate, and nicotine succinate performed well, followed by nicotine pyruvate, nicotine citrate, and nicotine pyruvate. Based on the satisfaction study, nicotine salt formulations with acids having a vapor pressure ranging from >2.66 kPa at 200°C, or 2.6-26.6 kPa at 200°C, or 13, 3 - 40 kPa at 200°C (> 20 mmHg at 200°C, or 20-200 mmHg at 200°C, or 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 been determined to have a vapor pressure of approximately 18.1 kPa (135.7 mmHg) at 200°C, benzoic acid has a vapor pressure of approximately 22.9 kPa (171.7 mmHg). mmHg) at 200°C, lauric acid has a vapor pressure of about 5.06 kPa (38 mmHg) at 200°C, and levulinic acid has a vapor pressure of about 19.9 kPa (149 mmHg) at 2002C. Example 4: Test Formulation 1 (TF1) (comparative) : A solution of nicotine levulinate in glycerol comprising nicotine salt used: 1.26 g (12.6% w / w) of nicotine levulinate 1:38.74 g (87.4% w / w) of glycerol - Total weight 10.0 g. Pure nicotine levulinate was added to the glycerol and mixed thoroughly. L-nicotine has a molar mass of 162.2 g, and the molar mass of levulinic acid is 116.1 g. In a 1:3 molar ratio, the percentage of nicotine in nicotine levulinate by weight is given by: 162.2 g / (162.2 g + (3 x 116.1 g)) = 31.8% ( w / w). Example 5: Test Formulation 2 (TF2) (Comparative) : A glycerol nicotine free base solution comprising 0.40 g (4.00% w / w) L-nicotine was dissolved in 9.60 g (96.0% w / w) glycerol and mixed thoroughly. . Example 6: Study of the heart rate of nicotine solutions through an electronic cigarette: Both formulations (TF1 and TF2) were administered in the same manner via electronic cigarette to the same human subject: approximately 0.6 mL of each solution was loaded into an "eGo-C" cartridge atomizer (joyetech.com). The atomizer was then connected to an "eVic" electronic cigarette (from the same manufacturer). This model of electronic cigarette allows you to adjust the voltage, and therefore the wattage, through the atomizer. The operating temperature of the electronic cigarette is from about 150°C to about 250°C, or from about 180°C to about 220°C. The atomizer in both cases has a resistance of 2.4 ohms, and the electronic cigarette was set to 4.24 V, which resulted in 7.49 W of power. (P = VA2 / R) Heart rate was measured at a 30-second interval for ten minutes from the start of the puffs. Test participants took 10 puffs over 3 minutes in each case (solid line (2nd highest peak) : cigarette, dark dotted line (highest peak) : test formulation 1 (nicotine salt formulation - TF1), light dotted line: test formulation 2 (nicotine formulation - TF2) The comparison between cigarette, TF1 and TF2 is shown in Figure 2. It is clearly shown in Figure 2 that the test formulation with nicotine levulinate (TF1) causes a more rapid increase in heart rate than nicotine alone (TF2). Also, TF1 is more like the rate of rise for a cigarette. Other salts have been tested and have also been found to increase heart rate relative to a pure nicotine solution. Therefore, other suitable nicotine salts that cause the similar effect can be used in accordance with the practice of the present invention. For example, other keto acids (alpha-keto acids, beta-keto acids, gamma-keto acids, and the like) such as pyruvic acid, oxalacetic acid, acetoacetic acid, and the like. This heart rate increase experience comparable to that of a traditional burning cigarette has not been demonstrated or identified in other e-cigarette devices, nor has it been demonstrated or identified in low-temperature tobacco vaporizing devices that do not burn tobacco, even when a nicotine salt (a 20% (w / w) or higher solution of nicotine salt) was used as a tobacco additive. Therefore, the results of this experiment are surprising and unexpected. Furthermore, the data seem to correlate well with the previous findings shown in figure 2. As noted earlier in the satisfaction study, nicotine salt formulations with acids having vapor pressures between 2.66 and 40 kPa (20-300 mmHg) at 200°C provide more satisfaction than the rest, with the exception of the nicotine salt formulation made with pyruvic acid, which has a boiling point of 165°C, as indicated in Figure 3. Based on the findings herein, it was anticipated that these salt formulations of nicotine have either:) - a vapor pressure between 2, 66 and 40 kPa (20-300 mmHg) at 200°C, - a vapor pressure >2.66 kPa (>20 mmHg) at 200°C, - a difference between the boiling point and the melting point of at least 50°C, and a boiling point greater than 160°C, and a melting point less than 160°C, - a difference between the boiling point and the melting point of at least 50°C, and a boiling point greater than 160°C, and a melting point less than 160°C, - a difference between the boiling point and the melting point of at least 50°C, and a boiling point at most 40°C lower than the operating temperature, and a melting point at least 40°C lower than the operating temperature, or - a combination of them produces one or more of the following effects: Tmax - Time to Peak Blood Concentration: Based on the results set forth herein, a user of an electronic cigarette comprising the nicotine salt formulation will experience a comparable rate of physical and emotional satisfaction from use of a formulation comprising a mixture of nicotine salts prepared with an appropriate acid at least 1.2X to 3X faster than using a formulation comprising a nicotine free base. As illustrated in Figure 1: Nicotine from a nicotine salt formulation appears to generate a heartbeat that is nearly 1.2 times that of a normal heart rate for an individual approximately 40 seconds after the start of puffing; whereas nicotine from a nicotine free base formulation appears to generate a heartbeat that is nearly 1.2 times that of a normal heart rate for an individual approximately 110 seconds after the start of puffs; a difference of 2.75 X in time to achieve a comparable initial level of satisfaction. Again, this would not be inconsistent with the data in Figure 2, where the data illustrated that at approximately 120 seconds (2 minutes), the test participants' heart rate peaked at 105-110 bpm with a regular cigarette or a nicotine salt formulation (TF1); whereas the heart rates of those same participants only peaked at approximately 86 bpm at approximately 7 minutes with a nicotine free base (TF2) formulation; also a 1.2-fold difference in effect with nicotine salts (and regular cigarettes) versus nicotine free base. Furthermore, when considering peak satisfaction levels (attained approximately 120 seconds from the start of puffs (time=0) and looking at the slope of the line for a normalized heart rate, the approximate slope of those salt formulations nicotine overruns for the nicotine free base formulation range from 0.0054 hrn / s to 0.0025 hrn / s In comparison, the slope of the line for the nicotine free base formulation is approximately 0.002. that the concentration of nicotine available will be delivered to the user at a rate that is between 1.25 and 2.7 times faster than a free base formulation. In another measure of performance; Cmax - Maximum concentration of nicotine in the blood; it is anticipated that similar rates of increase in blood nicotine concentration, such as those illustrated above, will be measured. That is, it was anticipated based on the findings herein, and unexpected based on the art known to date, that there would be comparable Cmax between the regular cigarette and certain nicotine salt formulations, but with a lower Cmax in a solution. nicotine free base. Similarly, it was anticipated based on the findings herein, and unexpected based on the art known to date, that certain nicotine salt formulations would have a higher rate of absorption levels of nicotine in the blood in periods of early time. In fact, Example 8 presents data for multiple salt formulations consistent with these predictions which were made based on the findings and tests reported herein, and were unexpected compared to the art available to date. Example 7: study of the heart rate of nicotine solutions through an electronic cigarette Exemplary 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 as indicated in Example 1 and administered in the same manner by electronic cigarette to the same human subject. Approximately 0.5 mL of each solution is loaded into an "eRoll" cartridge atomizer (joyetech.com) for use in the study. The atomizer is then connected to an "eRoll" electronic cigarette (from the same manufacturer). The operating temperature of the electronic cigarette is from about 150°C to about 250°C, or from about 180°C to about 220°C. Heart rate measurements are taken over 6 minutes; from 1 minute before the start of the puffs, for 3 minutes during the puffs, and continuing until 2 minutes after the end of the puffs. The test participant takes 10 puffs over 3 minutes in each case. Base heart rate is your average heart rate over the first minute before you start puffing. Heart rate after starting puffs is averaged over 20-second intervals. Normalized heart rate is defined as the ratio of the individual heart rate data point to the base heart rate. Final results are presented as normalized heart rate. Example 8: Blood Plasma Test Blood plasma tests were performed on three subjects (n = 3). Eight test items were used in this study: a reference cigarette and seven blends used in an e-cigarette device having an e-cigarette operating temperature of from about 150°C to about 250°C, or from about 180°C. C to about 220°C. The reference cigarette was Pall Mall (New Zealand). Seven blends were tested in the e-cigarette: 2% free base, 2% benzoate, 4% benzoate, 2% citrate, 2% malate, 2% salicylate, and 2% succinate. Except for 2% succinate (n=1), all other blends have n=3. All seven blends were liquid formulations prepared as described in Example 1. The concentration of nicotine in each of the formulations was confirmed using a UV spectrophotometer (Car y 60, manufactured by Agilent). Sample solutions for UV analysis were prepared by dissolving 20 mg of each of the formulations in 20 mL of 0.3% HCl in water. The sample solutions were then scanned in a UV spectrophotometer and the characteristic nicotine peak at 259 nm was used to quantify the nicotine in the sample against a standard solution of 19.8 pg / ml nicotine in the same. diluent. The stock solution was prepared by first dissolving 19.8 mg of nicotine in 10 ml of 0.3% HCl in water followed by a 1:100 dilution with 0.3% HCl in water. Reported nicotine concentrations for all formulations were within the range of 95%-105% of the declared concentrations. All subjects were able to consume 30-55 mg of the liquid formulation of each mixture tested using the electronic cigarette. Literature results: C. Bullen et al, Tobacco Control 2010, 19:98-103 Cigarette (5 min adlib, n=9): Tmax = 14.3 (8, 8-19.9), Cmax = 13, 4 (6.5-20.3) 1.4% E-cigarette (5 min adlib, n=8) : Tmax = 19.6 (4.9-34.2) , Cmax = 1.3 (0. 0-2.6) Nicorette inhaler (20 mg / 20 min, n=10) : Tmax = 32.0 (18.7-45.3) , Cmax = 2.1 (1.0-3.1) Estimated Cmax of 2% nicotine blends: Cmax = Mass Consumed * Potency * Bioavailability / (Vol. of Distribution * Body Weight) = 40 mg * 2% * 80% / (2.6L / kg * 75kg) = 3.3ng / mL Estimated Cmax of 4% nicotine blends: Cmax = Mass Consumed * Potency * Bioavailability / (Vol. of Distribution * Body Weight) = 40 mg * 4% * 80% / (2.6L / kg * 75kg) = 6.6ng / mL Figure 4 shows the pharmacokinetic profiles of the blood plasma tests; showing blood nicotine concentrations (ng / mL) over time after the first puff (inhalation) of e-cigarette aerosol or Pall Mall smoke. Ten puffs were taken at 30-s intervals starting at time = 0 and continuing for 4.5 minutes. For ease of reference and review of Figure 4, at the 5-minute time point, the curves on the graph show from top to bottom (from the highest average blood nicotine concentration to the lowest average blood nicotine concentration). low) are 4% benzoate, 2% succinate, 2% salicylate, 2% citrate, Pall Mall cigarette, 2% benzoate, 2% malate, and 2% blend. free base. Although listed from highest to lowest at this time point, this is not to say that there is a statistically significant difference between any of the salt formulations, or between any of the salt formulations and the Pall Mall cigarette. However, it is possible that there is a statistically significant difference between the Cmax of particular salt formulations, and it is also likely based on the data shown in Figure 4 and other studies herein that the free base formulation is statistically different from the salt formulations. and / or Pall Mall with respect to Cmax as it appears lower than others tested at various time points. One of ordinary skill in the art, upon review of the disclosure herein, could appropriately conduct a test to determine actual statistically based differences between one or more formulations and the cigarette, or between the formulations themselves in an electronic cigarette. For ease of reference, Tables 1 and 2 present the amount of nicotine detected (as an average across all users) for each formulation and the Pall Mall, presented in ng / mL, along with Cmax and Tmax and AUC. The data from these tables, along with the raw data therefore, were used to generate figures 4, 5 and 6. Table 1 Table 2 Figure 5 shows the comparison of Tmax and Cmax of the seven blends and the reference cigarette. The comparison of Cmax and AUC of the seven blends and the reference cigarette is shown in Figure 6. Due to the time limit of the washout period, the baseline blood nicotine concentration (at t=-2 and t=0 min) was higher for samples consumed later on the day of testing. The data in Figures 4-6 show corrected blood nicotine concentration values ​​(ie, apparent blood nicotine concentration at each time point minus the reference nicotine concentration from the same sample). Table 3 shows the absorption rates of nicotine in the blood of the users of each sample within the first 90 seconds. Table 3 Although the Tmax and Cmax values ​​are comparable between the tested blends and the reference cigarette (with the exception of the 2% free base blend), the nicotine absorption rates within the first 90 seconds differ between the tested blends. test items. In particular, four blends (2% salicylate, 2% benzoate, 4% benzoate, and 2% citrate) showed markedly higher absorption rates within the first 90 seconds compared to the other blends and the regular cigarette. reference. These four blends contain salts (salicylate, benzoate, and citrate) that performed well in the Example 3 satisfaction study. Additionally, 2% benzoate and 4% benzoate had comparable absorption rates, suggesting that a lower nicotinic salt concentration may not adversely impact absorption rate. Example 9: Blood plasma tests Blood plasma tests are carried out on 24 subjects (n = 24). Eight test items are used in this study: a reference cigarette and seven blends delivered to a user in an electronic cigarette as an aerosol. The operating temperature of the electronic cigarette is from about 150°C to about 250°C, or from about 180°C to about 220°C. The reference cigarette is Pall Mall (New Zealand). Seven blends are tested: 2% free base, 2% benzoate, 4% benzoate, 2% citrate, 2% malate, 2% salicylate, and 2% succinate. All seven blends are liquid formulations prepared according to protocols similar to that described below and in Example 1. All subjects should consume 30-55 mg of the liquid formulation of each mixture tested. Ten puffs should be taken at 30 s intervals starting at time = 0 and continuing for 4.5 min. Blood plasma testing must be performed for at least 60 minutes from the first puff (t=0) Pharmacokinetic data (eg, Cmax, Tmax, AUC) for nicotine are obtained in the plasma of users at various time periods during those 60 minutes, along with nicotine absorption rates within the first 90 seconds for each test item. Example 10: Blood plasma tests Twenty-four subjects (n=24) are tested for blood plasma. Eleven test items are used in this study: a reference cigarette and ten blends delivered to a user in an electronic cigarette as an aerosol. The reference cigarette is Pall Mall (New Zealand). The operating temperature of the electronic cigarette is from about 150°C to about 250°C, or from about 180°C to about 220°C. Ten mixtures are tested: 2% free base, 2% benzoate, 2% sorbate, 2% pyruvate, 2% laurate, 2% levulinate, 2% citrate, 2% malate, 2% salicylate and 2% succinate. All ten blends are liquid formulations prepared according to protocols similar to that described below and in Example 1. All subjects should consume 30-55 mg of the liquid formulation of each mixture tested. Ten puffs should be taken at 30 s intervals starting at time = 0 and continuing for 4.5 min. Blood plasma tests must be performed for at least 60 minutes from the first puff (t=0). Pharmacokinetic data (eg, Cmax, Tmax, AUC) for nicotine in the plasma of users are obtained at various time periods during those 60 minutes, along with nicotine absorption rates within the first 90 seconds for each item. test. Example 11: Blood plasma tests Twenty-four subjects (n=24) are tested for blood plasma. Twenty-one test items are used in this study: a reference cigarette and twenty blends delivered to a user in an electronic cigarette as an aerosol. The reference cigarette is Pall Mall (New Zealand). The operating temperature of the electronic cigarette is from about 150°C to about 250°C, or from about 180°C to about 220°C. Twenty mixtures are tested: 2% free base, 4% free base, 2% benzoate, 4% benzoate, 2% sorbate, 4% sorbate, 2% pyruvate, 4% pyruvate, 2 % Laurate, 4% Laurate, 2% Levulinate, 4% Levulinate, 2% Citrate, 4% Citrate, 2% Malate, 4% Malate, 2% Salicylate, 4% Salicylate, 2 % succinate and 4% succinate. All twenty blends are liquid formulations prepared according to protocols similar to that described below and in Example 1. All subjects should consume 30-55 mg of the liquid formulation of each mixture tested. Ten puffs should be taken at 30 s intervals starting at time = 0 and continuing for 4.5 min. The blood plasma test must be performed for at least 60 minutes from the first puff (t=0). Pharmacokinetic data (eg, Cmax, Tmax, AUC) for nicotine in the plasma of users are obtained at various time periods during those 60 minutes, along with nicotine absorption rates within the first 90 seconds for each item. test. Example 12: Blood plasma tests Twenty-four subjects (n=24) are tested for blood plasma. Twenty-one test items are used in this study: a reference cigarette and twenty blends delivered to a user in an electronic cigarette as an aerosol. The reference cigarette is Pall Mall (New Zealand). The operating temperature of the electronic cigarette is from about 150°C to about 250°C, or from about 180°C to about 220°C. Twenty mixtures are tested: 2% free base, 1% free base, 2% benzoate, 1% benzoate, 2% sorbate, 1% sorbate, 2% pyruvate, 1% pyruvate, 2% % Laurate, 1% Laurate, 2% Levulinate, 1% Levulinate, 2% Citrate, 1% Citrate, 2% Malate, 1% Malate, 2% Salicylate, 1% Salicylate, 2 % succinate and 1% succinate. All twenty blends are liquid formulations prepared according to protocols similar to that described below and in Example 1. All subjects should consume 30-55 mg of the liquid formulation of each mixture tested. Ten puffs should be taken at 30 s intervals starting at time = 0 and continuing for 4.5 min. Blood plasma tests must be performed for at least 60 minutes from the first puff (t=0). Pharmacokinetic data (eg, Cmax, Tmax, AUC) for nicotine in the plasma of users are obtained at various time periods during those 60 minutes, along with nicotine absorption rates within the first 90 seconds for each item. test. The present disclosure provides the following illustrative examples that are useful in understanding the invention. Example E1: A method of delivering nicotine to a user comprising operating an electronic cigarette to a user wherein the electronic cigarette comprises a nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to forming said nicotine salt is characterized by a vapor pressure >20 mmHg at 200°C, and inhaling an aerosol generated from the heated nicotine salt formulation by the electronic cigarette. Example E2: A method of delivering nicotine to a user comprising operating an electronic cigarette to a user wherein the electronic cigarette comprises a nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to forming said nicotine salt is characterized by a vapor pressure of about 20 to 200 mmHg at 200°C, and inhaling an aerosol generated from the heated nicotine salt formulation by the electronic cigarette. Example E3: A method of delivering nicotine to a user comprising operating an electronic cigarette wherein the electronic cigarette comprises a nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said salt of nicotine is further characterized by a melting point <160°C, a boiling point >160°C, and at least a 50 degree difference between the melting point and the boiling point, and inhaling an aerosol generated from of the nicotine salt formulation heated by the electronic cigarette. Example E4: A method of delivering nicotine to a user comprising providing an electronic cigarette to a user wherein the electronic cigarette comprises a nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to forming said nicotine salt is further characterized by a melting point at least 40 degrees lower than the operating temperature of the electronic cigarette, a boiling point not more than 40 degrees lower than the operating temperature of the electronic cigarette, and at least one difference of 50 degrees between the melting point and the boiling point, and inhaling an aerosol generated from the nicotine salt formulation heated by the electronic cigarette. Example E5: The method of any one of Examples E1-3, wherein the operating temperature is from 150°C to 250°C. Example E6: The method of any one of Examples E1-3, wherein the operating temperature is from 180°C to 220°C. Example E7: The method of any one of Examples E1-3, wherein the operating temperature is about 200°C. Example E8: The method of Example E4, wherein the operating temperature is from 150°C to 250°C. Example E9: The method of Example E4, where the operating temperature is from 180°C to 220°C. Example E10: The method of Example E4, where the operating temperature is about 200°C. Example E11: The method of any one of Examples E1-10, wherein the aerosol comprises nicotine salt condensate. Example E12: The method of any one of Examples E1-10, wherein the aerosol comprises nicotine free base condensate. Example E13: The method of any one of Examples E1-10, wherein the aerosol comprises nicotine free base condensate and carrier condensate. Example E14: The method of any one of Examples E1-10, wherein the aerosol comprises nicotine free base condensate and acid condensate. Example E15: The method of any one of Examples E1-14, wherein the aerosol comprises condensate in particle sizes of from about 0.1 microns to about 5 microns. Example E16: The method of any one of Examples E1-14, wherein the aerosol comprises condensate in particle sizes of from about 0.1 microns to about 1 or 2 microns. Example E17: The method of any one of Examples E1-14, wherein the aerosol comprises condensate in particle sizes of from about 0.1 microns to about 0.7 microns. Example E18: The method of any one of Examples E1-14, wherein the aerosol comprises condensate in particle sizes of from about 0.3 microns to about 0.4 microns. Example E19: The method of any one of Examples E1-18, wherein an acid used to form the nicotine salt is benzoic acid. Example E20: The method of any one of examples E1-18, wherein said nicotine salt comprises nicotine benzoate. Example E21: The method of any one of Examples E1-20, wherein the liquid carrier comprises glycerol, propylene glycol, trimethylene glycol, water, ethanol, or combinations thereof. Example E22: The method of any one of Examples E1-20, wherein the liquid carrier comprises propylene glycol and vegetable glycerin. Example E23: The method of any one of Examples E1-20, wherein the liquid carrier comprises 20% to 50% propylene glycol and 80% to 50% vegetable glycerin. Example E24: The method of any one of Examples E1-20, wherein the liquid carrier comprises 30% propylene glycol and 70% vegetable glycerin. Example E25: The method of any one of Examples E1-24, wherein the nicotine salt is in an amount that forms from about 0.5% to about 20% of the nicotine in the inhalable aerosol. Example E26: The method of any one of Examples E1-24, wherein the nicotine salt is in an amount that forms from about 1% to about 20% of the nicotine in the inhalable aerosol. Example E27: The method of any one of Examples E1-26, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 25% (w / w). Example E28: The method of any one of Examples E1-26, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 20% (w / w). Example E29: The method of any one of Examples E1-26, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 18% (w / w). Example E30: The method of any one of Examples E1-26, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 15% (w / w). Example E31: The method of any one of Examples E1-26, wherein the liquid formulation has a nicotine concentration of from about 4% (w / w) to about 12% (w / w). Example E32: The method of any one of Examples E1-26, wherein the liquid formulation has a nicotine concentration of about 4% (w / w). Example E33: The method of any one of Examples E1-26, wherein the liquid formulation has a nicotine concentration of about 2% (w / w). Example E34: The method of any one of Examples E1-33, wherein the formulation further comprises a flavoring agent. Example E35: The method of any one of Examples E1-34, wherein the formulation is non-corrosive to an electronic cigarette. Example E36: ​​The method of any one of Examples E1-35, wherein the acid is stable at and below operating temperature or about 200°C. Example E37: The method of any one of Examples E1-36, wherein the acid does not decompose at or below operating temperature or about 200°C. Example E38: The method of any one of Examples E1-37, wherein the acid is not oxidized at or below operating temperature or about 200°C. Example E39: The method of any one of Examples E1-38, wherein the formulation is not corrosive to the electronic cigarette. Example E40: The method of any one of Examples E1-39, wherein the formulation is non-toxic to an electronic cigarette user. Example E41: The method of any one of Examples E1-40, wherein the formulation further comprises one or more additional nicotine salts in a biologically acceptable liquid carrier suitable for generating the inhalable aerosol upon heating. Example E42: The method of Example E41, wherein a 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. Example E43: A method of delivering nicotine to a user's blood, said method comprising providing an aerosol that the user inhales from an electronic cigarette comprising a nicotine salt formulation wherein providing the aerosol comprises the electronic cigarette heating the formulation thereby generating the aerosol, wherein the aerosol is effective to deliver a user's blood level of nicotine that is at least 5 ng / mL at about 1.5 minutes after a first ten-puff puff of the aerosol, each puff taken at 30 second intervals. Example E44: The method of Example E40, wherein the nicotine salt formulation comprises a nicotine salt in a biologically acceptable liquid carrier, wherein an acid used to form said nicotine salt is characterized by a vapor pressure >20 mmHg at 200°C. Example E45: The method of Example E40, wherein the nicotine salt formulation comprises a nicotine salt in a biologically acceptable liquid carrier, wherein an acid used to form said nicotine salt is characterized by a vapor pressure of about 20 at 200mmHg at 200°C. Example E46: The method of Example E40, wherein the nicotine salt formulation comprises a nicotine salt in a biologically acceptable liquid carrier, wherein an acid used to form said nicotine salt is further characterized by a melting point <160 °C, a boiling point >160°C, and at least a 50 degree difference between the melting point and the boiling point. Example E47: The method of any one of Examples E43-46, wherein the heating of the formulation is to a temperature of from 150°C to 250°C. Example E48: The method of any one of Examples E43-46, wherein the heating of the formulation is to a temperature of from 180°C to 220°C. Example E49: The method of any one of Examples E43-46, wherein the heating of the formulation is to a temperature of about 200°C. Example E50: The method of Example E40, wherein the nicotine salt formulation comprises a nicotine salt in a biologically acceptable liquid carrier, wherein an acid used to form said nicotine salt is further characterized by a melting point of at least 40 degrees lower than the operating temperature of the electronic cigarette, a boiling point not more than 40 degrees lower than the operating temperature of the electronic cigarette, and a difference of at least 50 degrees between the melting point and the boiling point; and the operating temperature is 200°C. Example E51: The method of any one of Examples E43-50, wherein the Cmax is above 10 ng / ml on average. Example E52: The method of any one of Examples E43-50, wherein the Cmax is above 11 ng / ml on average. Example E53: The method of any one of Examples E43-50, wherein Cmax is between 10 ng / ml and 16 ng / ml on average. Example E54: The method of any one of Examples E43-50, wherein Cmax is between 11 ng / ml and 15 ng / ml on average. Example E55: The method of any one of Examples E43-50, wherein Cmax is between 11 ng / ml and 14 ng / ml on average. Example E56: The method of any one of Examples E43-55, wherein the Tmax is below 10 minutes on average. Example E57: The method of any one of Examples E43-55, wherein the Tmax is below 9 minutes on average. Example E58: The method of any one of Examples E43-55, wherein the Tmax is below 8 minutes on average. Example E59: The method of any one of Examples E43-55, wherein the Tmax is below 7 minutes on average. Example E60: The method of any one of Examples E40-49, wherein the Tmax is from 3 minutes to 10 minutes on average. Example E61: The method of any one of Examples E43-55, wherein the Tmax is from 3 minutes to 7.5 minutes on average. Example E62: The method of any one of Examples E43-61, wherein the aerosol comprises nicotine salt condensate. Example E63: The method of any one of Examples E43-61, wherein the aerosol comprises nicotine free base condensate. Example E64: The method of any one of Examples E43-61, wherein the aerosol comprises nicotine free base condensate and carrier condensate. Example E65: The method of any one of Examples E43-61, wherein the aerosol comprises nicotine free base condensate and acid condensate. Example E66: The method of any one of Examples E43-65, wherein the aerosol comprises condensate in particle sizes of from about 0.1 microns to about 5 microns. Example E67: The method of any one of Examples E43-65, wherein the aerosol comprises condensate in particle sizes of from about 0.1 microns to about 1 or 2 microns. Example E68: The method of any one of Examples E43-65, wherein the aerosol comprises condensate in particle sizes of from about 0.1 microns to about 0.7 microns. Example E69: The method of any one of Examples E43-65, wherein the aerosol comprises condensate in particle sizes of from about 0.3 microns to about 0.4 microns. Example E70: The method of any one of Examples E43-69, wherein an acid used to form the nicotine salt is benzoic acid. Example E71: The method of any one of Examples E43-69, wherein said nicotine salt comprises nicotine benzoate. Example E72: The method of any one of Examples E43-71, wherein the liquid carrier comprises glycerol, propylene glycol, trimethylene glycol, water, ethanol, or combinations thereof. Example E73: The method of any one of Examples E43-71, wherein the liquid carrier comprises propylene glycol and vegetable glycerin. Example E74: The method of any one of Examples E43-71, wherein the liquid carrier comprises 20% to 50% propylene glycol and 80% to 50% vegetable glycerin. Example E75: The method of any one of Examples E43-71, wherein the liquid carrier comprises 30% propylene glycol and 70% vegetable glycerin. Example E76: The method of any one of Examples E43-75, wherein the nicotine salt is in an amount that forms from about 0.5% to about 20% of the nicotine in the inhalable aerosol. Example E77: The method of any one of Examples E43-75, wherein the nicotine salt is in an amount that forms from about 1% to about 20% of the nicotine in the inhalable aerosol. Example E78: The method of any one of Examples E43-77, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 25% (w / w). Example E79: The method of any one of Examples E43-77, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 20% (w / w). Example E80: The method of any one of Examples E43-77, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 18% (w / w). Example E81: The method of any one of Examples E43-77, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 15% (w / w). Example E82: The method of any one of Examples E43-77, wherein the liquid formulation has a nicotine concentration of from about 4% (w / w) to about 12% (w / w). Example E83: The method of any one of Examples E43-77, wherein the liquid formulation has a nicotine concentration of about 4% (w / w). Example E84: The method of any one of Examples E43-77, wherein the liquid formulation has a nicotine concentration of about 2% (w / w). Example E85: The method of any one of Examples E43-84, wherein the formulation further comprises a flavouring. Example E86: The method of any one of Examples E43-85, wherein the formulation is non-corrosive to an electronic cigarette. Example E87: The method of any one of Examples E43-86, wherein the acid is stable at and below operating temperature or about 200°C. Example E88: The method of any one of Examples E43-87, wherein the acid does not decompose at or below operating temperature or about 200°C. Example E89: The method of any one of Examples E43-88, wherein the acid is not oxidized at or below operating temperature or about 200°C. Example E90: The method of any one of Examples E43-89, wherein the formulation is not corrosive to the electronic cigarette. Example E91: The method of any one of Examples E43-90, wherein the formulation is non-toxic to an electronic cigarette user. Example E92: The method of any one of Examples E43-91, wherein the formulation further comprises one or more additional nicotine salts in a biologically acceptable liquid carrier suitable for generating the inhalable aerosol upon heating. Example E93: The method of Example E92, wherein a 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. Example E94: A liquid nicotine salt formulation in an electronic cigarette for generating an inhalable aerosol upon heating in the electronic cigarette, the cigarette formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is characterized by a vapor pressure >20 mmHg at 200°C. Example E95: A liquid nicotine salt formulation in an electronic cigarette for generating an inhalable aerosol upon heating in the electronic cigarette, the cigarette formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said Nicotine salt is characterized by a vapor pressure of about 20 to 200 mmHg at 200°C. Example E96: A liquid nicotine salt formulation in an electronic cigarette for generating an inhalable aerosol upon heating in the electronic cigarette, the cigarette formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is further characterized by a melting point <160°C, a boiling point >160°C, and at least a 50 degree difference between the melting point and the boiling point. Example E97: A liquid nicotine salt formulation in an electronic cigarette for generating an inhalable aerosol upon heating in the electronic cigarette, the cigarette formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is further characterized by a melting point at least 40 degrees lower than the operating temperature of the electronic cigarette, a boiling point not more than 40 degrees lower than the operating temperature of the electronic cigarette, and at least a difference of 50 degrees between the melting point and the boiling point. Example E98: The liquid nicotine salt formulation in the electronic cigarette of any one of Examples E94-96, wherein the electronic cigarette heats the nicotine salt formulation to an operating temperature of from 150°C to 250°C . Example E99: The liquid nicotine salt formulation in the electronic cigarette of any one of Examples E94-96, wherein the electronic cigarette heats the nicotine salt formulation to an operating temperature of from 180°C to 220°C . Example E100: The liquid nicotine salt formulation in the electronic cigarette of any one of Examples E94-96, wherein the electronic cigarette heats the nicotine salt formulation to an operating temperature of about 200°C. Example E101: The liquid nicotine salt formulation in the electronic cigarette of Example E97, wherein the operating temperature is from 150°C to 250°C. Example E102: The liquid nicotine salt formulation in the electronic cigarette of Example E97, wherein the operating temperature is from 180°C to 220°C. Example E103: The liquid nicotine salt formulation in the electronic cigarette of Example E97, wherein the operating temperature is about 200°C. Example E104: The liquid nicotine salt formulation in the electronic cigarette of any one of Examples E94-103, wherein the acid used to form the nicotine salt is benzoic acid. Example E105: The liquid formulation of nicotine salt in the electronic cigarette of any one of examples E94-103, wherein said nicotine salt comprises nicotine benzoate. Example E106: The liquid nicotine salt formulation in the electronic cigarette of any one of Examples E94-105, wherein the liquid carrier comprises glycerol, propylene glycol, trimethylene glycol, water, ethanol, or combinations thereof. Example E107: The liquid nicotine salt formulation in the electronic cigarette of any one of Examples E94-105, wherein the liquid carrier comprises propylene glycol and vegetable glycerin. Example E108: The liquid nicotine salt formulation in the electronic cigarette of any one of Examples E94-105, wherein the liquid carrier comprises 20% to 50% propylene glycol and 80% to 50% vegetable glycerin. Example E109: The liquid nicotine salt formulation in the electronic cigarette of any one of Examples E94-105, wherein the liquid carrier comprises 30% propylene glycol and 70% vegetable glycerin. Example E110: The liquid nicotine salt formulation in the electronic cigarette of any one of Examples E94-109, wherein the nicotine salt is in an amount that forms from about 0.5% to about 20% nicotine in the inhalable aerosol. Example E111: The liquid nicotine salt formulation in the electronic cigarette of any one of Examples E94-109, wherein the nicotine salt is in an amount that forms from about 1% to about 20% of nicotine in the inhalable aerosol. Example E112: The liquid nicotine salt formulation in the electronic cigarette of any one of Examples E94-111, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 25% ( w / w). Example E113: The liquid nicotine salt formulation in the electronic cigarette of any one of Examples E94-111, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 20% ( w / w). Example E114: The liquid nicotine salt formulation in the electronic cigarette of any one of Examples E94-111, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 18% ( w / w). Example E115: The liquid nicotine salt formulation in the electronic cigarette of any one of Examples E94-111, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 15% ( w / w). Example E116: The liquid nicotine salt formulation in the electronic cigarette of any one of Examples E94-111, wherein the liquid formulation has a nicotine concentration of from about 4% (w / w) to about 12% ( w / w). Example E117: The liquid nicotine salt formulation in the electronic cigarette of any one of Examples E94-111, wherein the liquid formulation has a nicotine concentration of approximately 4% (w / w). Example E118: The liquid nicotine salt formulation in the electronic cigarette of any one of Examples E94-111, wherein the liquid formulation has a nicotine concentration of approximately 2% (w / w). Example E119: The liquid nicotine salt formulation in the electronic cigarette of any one of Examples E94-118, wherein the formulation further comprises a flavoring agent. Example E120: The liquid nicotine salt formulation in the electronic cigarette of any one of Examples E94-119, wherein the formulation is non-corrosive to an electronic cigarette. Example E121: The liquid nicotine salt formulation in the electronic cigarette of any one of Examples E94-120, wherein the acid is stable at and below operating temperature or about 200°C. Example E122: The liquid nicotine salt formulation in the electronic cigarette of any one of Examples E94-121, wherein the acid does not decompose at or below operating temperature or about 200°C. Example E123: The liquid nicotine salt formulation in the electronic cigarette of any one of Examples E94-122, wherein the acid does not oxidize at or below operating temperature or about 200°C. Example E124: The liquid nicotine salt formulation in the electronic cigarette of any one of Examples E94-123, wherein the formulation is not corrosive to the electronic cigarette. Example E125: The liquid nicotine salt formulation in the electronic cigarette of any one of Examples E94-124, wherein the formulation is non-toxic to a user of the electronic cigarette. Example E126: The liquid nicotine salt formulation in the electronic cigarette of any one of Examples E94-125 further comprising one or more additional nicotine salts in a biologically acceptable liquid carrier suitable for generating the inhalable aerosol upon heating. Example E127: The liquid nicotine salt formulation in the electronic cigarette of Example E126, wherein a 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. Example E128: A liquid nicotine salt formulation for generating an inhalable aerosol upon heating in the electronic cigarette, the liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt Nicotine is characterized by a vapor pressure >20 mmHg at 200°C. Example E129: A liquid nicotine salt formulation for generating an inhalable aerosol upon heating in the electronic cigarette, the liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt Nicotine is characterized by a vapor pressure of approximately 20 to 200 mmHg at 200°C. Example E130: A liquid nicotine salt formulation for generating an inhalable aerosol upon heating in the electronic cigarette, the liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt Nicotine is further characterized by a melting point <160°C, a boiling point >160°C, and a difference of at least 50 degrees between the melting point and the boiling point. Example E131: A liquid nicotine salt formulation for generating an inhalable aerosol upon heating in the electronic cigarette, the liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt nicotine is further characterized by a melting point at least 40 degrees lower than the operating temperature of the electronic cigarette, a boiling point not more than 40 degrees lower than the operating temperature of the electronic cigarette, and at least a difference of 50 degrees between the melting point and the boiling point. Example E132: The liquid nicotine salt formulation of any one of Examples E128-130, wherein the electronic cigarette heats the nicotine salt formulation to an operating temperature of from 150°C to 250°C. Example E133: The liquid nicotine salt formulation of any one of Examples E128-130, wherein the electronic cigarette heats the nicotine salt formulation to an operating temperature of from 180°C to 220°C. Example E134: The liquid nicotine salt formulation of any one of Examples E128-130, wherein the electronic cigarette heats the nicotine salt formulation to an operating temperature of about 200°C. Example E135: The liquid nicotine salt formulation of Example E131, wherein the operating temperature is from 150°C to 250°C. Example E136: The liquid nicotine salt formulation of Example E131, wherein the operating temperature is from 180°C to 220°C. Example E137: The liquid nicotine salt formulation of Example E131, wherein the operating temperature is about 200°C. Example E138: The liquid nicotine salt formulation of any one of Examples E128-137, wherein the acid used to form the nicotine salt is benzoic acid. Example E139: The liquid nicotine salt formulation of any one of Examples E128-137, wherein said nicotine salt comprises nicotine benzoate. Example E140: The liquid nicotine salt formulation of any one of Examples E128-139, wherein the liquid carrier comprises glycerol, propylene glycol, trimethylene glycol, water, ethanol, or combinations thereof. Example E141: The liquid nicotine salt formulation of any one of Examples E128-139, wherein the liquid carrier comprises propylene glycol and vegetable glycerin. Example E142: The liquid nicotine salt formulation of any one of Examples E128-139, wherein the liquid carrier comprises 20% to 50% propylene glycol and 80% to 50% vegetable glycerin. Example E143: The liquid nicotine salt formulation of any one of Examples E128-139, wherein the liquid carrier comprises 30% propylene glycol and 70% vegetable glycerin. Example E144: The liquid nicotine salt formulation of any one of Examples E128-143, wherein the nicotine salt is in an amount that forms from about 0.5% to about 20% of the nicotine in the inhalable aerosol . Example E145: The liquid nicotine salt formulation of any one of Examples E128-143, wherein the nicotine salt is in an amount that forms from about 1% to about 20% of the nicotine in the inhalable aerosol. Example E146: The liquid nicotine salt formulation of any one of Examples E128-145, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 25% (w / w) . Example E147: The liquid nicotine salt formulation of any one of Examples E128-145, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 20% (w / w) . Example E148: The liquid nicotine salt formulation of any one of Examples E128-145, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 18% (w / w) . Example E149: The liquid nicotine salt formulation of any one of Examples E128-145, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 15% (w / w) . Example E150: The liquid nicotine salt formulation of any one of Examples E128-145, wherein the liquid formulation has a nicotine concentration of from about 4% (w / w) to about 12% (w / w) . Example E151: The liquid nicotine salt formulation of any one of Examples E128-145, wherein the liquid formulation has a nicotine concentration of about 4% (w / w). Example E152: The liquid nicotine salt formulation of any one of Examples E128-145, wherein the liquid formulation has a nicotine concentration of about 2% (w / w). Example E153: The liquid nicotine salt formulation of any one of Examples E128-152, wherein the formulation further comprises a flavouring. Example E154: The liquid nicotine salt formulation of any one of Examples E128-153, wherein the formulation is non-corrosive to an electronic cigarette. Example E155: The liquid nicotine salt formulation of any one of Examples E128-154, wherein the acid is stable at and below operating temperature or about 200°C. Example E156: The liquid nicotine salt formulation of any one of Examples E128-155, wherein the acid does not decompose at or below operating temperature or about 200°C. Example E157: The liquid nicotine salt formulation of any one of Examples E128-156, wherein the acid does not oxidize at or below operating temperature or about 200°C. Example E158: The liquid nicotine salt formulation of any one of Examples E128-157, wherein the formulation is non-corrosive to the electronic cigarette. Example E159: The liquid nicotine salt formulation of any one of Examples E128-158, wherein the formulation is non-toxic to an electronic cigarette user. Example E160: The liquid nicotine salt formulation of any one of Examples E128-159, further comprising one or more additional nicotine salts in a biologically acceptable liquid carrier suitable for generating the inhalable aerosol upon heating. Example E161: The liquid nicotine salt formulation of Example E160, wherein a 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 acid. levulinic. Example E162: A liquid nicotine salt formulation for use in an electronic cigarette, the liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is characterized by a vapor pressure >20 mmHg at 200°C. Example E163: A liquid nicotine salt formulation for use in an electronic cigarette, the liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is characterized by a vapor pressure of about 20 to 200 mmHg at 200°C. Example E164: A liquid nicotine salt formulation for use in an electronic cigarette, the liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is further characterized by a melting point <160°C, a boiling point >160°C, and at least a 50 degree difference between the melting point and the boiling point. Example E165: A liquid nicotine salt formulation for use in an electronic cigarette, the liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is further characterized by a melting point at least 40 degrees lower than the operating temperature of the electronic cigarette, a boiling point not more than 40 degrees lower than the operating temperature of the electronic cigarette, and a difference of at least 50 degrees between the point of melting and boiling point. Example E166: The liquid nicotine salt formulation of any one of Examples E162-164, wherein the electronic cigarette heats the nicotine salt formulation to an operating temperature of from 150°C to 2502C. Example E167: The liquid nicotine salt formulation of any one of Examples E162-164, wherein the electronic cigarette heats the nicotine salt formulation to an operating temperature of from 180°C to 220°C. Example E168: The liquid nicotine salt formulation of any one of Examples E162-164, wherein the electronic cigarette heats the nicotine salt formulation to an operating temperature of about 200°C. Example E169: The liquid nicotine salt formulation of Example E165, wherein the operating temperature is from 150°C to 250°C. Example E170: The liquid nicotine salt formulation of Example E165, wherein the operating temperature is from 180°C to 220°C. Example E171: The liquid nicotine salt formulation of Example E165, wherein the operating temperature is about 200°C. Example E172: The liquid nicotine salt formulation of any one of Examples E162-171, wherein the acid used to form the nicotine salt is benzoic acid. Example E173: The liquid nicotine salt formulation of any one of Examples E162-171, wherein said nicotine salt comprises nicotine benzoate. Example E174: The liquid nicotine salt formulation of any one of Examples E162-173, wherein the liquid carrier comprises glycerol, propylene glycol, trimethylene glycol, water, ethanol, or combinations thereof. Example E 175: The liquid nicotine salt formulation of any one of Examples E162-173, wherein the liquid carrier comprises propylene glycol and vegetable glycerin. Example E176: The liquid nicotine salt formulation of any one of Examples E162-173, wherein the liquid carrier comprises 20% to 50% propylene glycol and 80% to 50% vegetable glycerin. Example E177: The liquid nicotine salt formulation of any one of Examples E162-173, wherein the liquid carrier comprises 30% propylene glycol and 70% vegetable glycerin. Example E178: The liquid nicotine salt formulation of any one of Examples E162-177, wherein the nicotine salt is in an amount that forms from about 0.5% to about 20% of the nicotine in the inhalable aerosol . Example E179: The liquid nicotine salt formulation of any one of Examples E162-177, wherein the nicotine salt is in an amount that forms from about 1% to about 20% of the nicotine in the inhalable aerosol. Example E180: The liquid nicotine salt formulation of any one of Examples E162-177, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 25% (w / w) . Example E181: The liquid nicotine salt formulation of any one of Examples E162-177, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 20% (w / w) . Example E 182: The liquid nicotine salt formulation of any one of Examples E162-177, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 18% (w / w). ) . Example E183: The liquid nicotine salt formulation of any one of Examples E162-177, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 15% (w / w) . Example E184: The liquid nicotine salt formulation of any one of Examples E162-177, wherein the liquid formulation has a nicotine concentration of from about 4% (w / w) to about 12% (w / w) . Example E185: The liquid nicotine salt formulation of any one of Examples E162-177, wherein the liquid formulation has a nicotine concentration of about 4% (w / w). Example E186: The liquid nicotine salt formulation of any one of Examples E162-177, wherein the liquid formulation has a nicotine concentration of about 2% (w / w). Example E187: The liquid nicotine salt formulation of any one of Examples E162-186, wherein the formulation further comprises a flavouring. Example E188: The liquid nicotine salt formulation of any one of Examples E162-187, wherein the formulation is non-corrosive to an electronic cigarette. Example E189: The liquid nicotine salt formulation of any one of Examples E162-188, wherein the acid is stable at and below operating temperature or about 200°C. Example E190: The liquid nicotine salt formulation of any one of Examples E162-189, wherein the acid does not decompose at or below operating temperature or about 200°C. Example E191: The liquid nicotine salt formulation of any one of Examples E162-190, wherein the acid does not oxidize at or below operating temperature or about 200°C. Example E192: The liquid nicotine salt formulation of any one of Examples E162-191, wherein the formulation is not corrosive to the electronic cigarette. Example E193: The liquid nicotine salt formulation of any one of Examples E162-192, wherein the formulation is non-toxic to an electronic cigarette user. Example E194: The liquid nicotine salt formulation of any one of Examples E162-193, further comprising one or more additional nicotine salts in a biologically acceptable liquid carrier suitable for generating the inhalable aerosol upon heating. Example E195: The liquid nicotine salt formulation of Example E194, wherein a 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 acid levulinic. Example E196: Use of a nicotine salt formulation for delivery of nicotine to a user from an electronic cigarette wherein the nicotine salt formulation comprises a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is characterized by a vapor pressure >20 mmHg at 200°C, and the electronic cigarette heats the nicotine salt formulation to generate an aerosol inhalable by the user. Example E197: Use of a nicotine salt formulation for delivery of nicotine to a user from an electronic cigarette wherein the nicotine salt formulation comprises a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said Nicotine salt is characterized by a vapor pressure of about 20 to 200 mmHg at 200°C, and the electronic cigarette heats the nicotine salt formulation to generate an aerosol inhalable by the user. Example E198: Use of a nicotine salt formulation for delivery of nicotine to a user from an electronic cigarette wherein the nicotine salt formulation comprises a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is further characterized by a melting point <160°C, a boiling point >160°C, and at least a 50 degree difference between the melting point and the boiling point, and the electronic cigarette heats the nicotine salt formulation to generate an inhalable aerosol for the user. Example E199: Use of a nicotine salt formulation for delivery of 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 that delivers a high level of nicotine in the user's blood that is at least 5 ng / ml at about 1.5 minutes after a first puff of ten puffs of the aerosol, each puff taken at 30-second intervals. Example E200: Use of a nicotine salt formulation for delivery of nicotine to a user from an electronic cigarette wherein the nicotine salt formulation comprises a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is further characterized by a melting point at least 40 degrees lower than the operating temperature of the electronic cigarette, a boiling point not more than 40 degrees lower than the operating temperature of the electronic cigarette and at least no difference of 50 degrees between the melting point and the boiling point, and the electronic cigarette heats the nicotine salt formulation to generate an inhalable aerosol for the user. Example E201: Use of any one of Examples E196-199, wherein the electronic cigarette heats the nicotine salt formulation to an operating temperature of from 150°C to 250°C. Example E202: Use of any one of Examples E196-199, wherein the electronic cigarette heats the nicotine salt formulation to an operating temperature of from 180°C to 220°C. Example E203: The use of any one of Examples E196-199, wherein the electronic cigarette heats the nicotine salt formulation to an operating temperature of about 200°C. Example E204: Using example E200, where the operating temperature is from 150°C to 250°C. Example E205: The use of example E200, where the operating temperature is from 180°C to 220°C. Example E206: The use of example E200, where the operating temperature is approximately 200°C. Example E207: The use of any one of Examples E196-206, wherein the aerosol comprises nicotine salt condensate. Example E208: The use of any one of Examples E196-206, wherein the aerosol comprises nicotine free base condensate. Example E209: The use of any one of Examples E196-206, wherein the aerosol comprises nicotine free base condensate and carrier condensate. Example E210: The use of any one of Examples E196-206, wherein the aerosol comprises nicotine free base condensate and acid condensate. Example E211: The use of any one of Examples E196-210, wherein the aerosol comprises condensate in particle sizes of from about 0.1 microns to about 5 microns. Example E212: The use of any one of Examples E196-210, wherein the aerosol comprises condensate in particle sizes of from about 0.1 microns to about 1 or 2 microns. Example E213: The use of any one of Examples E196-210, wherein the aerosol comprises condensate in particle sizes of from about 0.1 microns to about 0.7 microns. Example E214: The use of any one of Examples E196-210, wherein the aerosol comprises condensate in particle sizes of from about 0.3 microns to about 0.4 microns. Example E215: The use of any one of Examples E196-214, wherein an acid used to form the nicotine salt is benzoic acid. Example E216: The use of any one of examples E196-214, wherein said nicotine salt comprises nicotine benzoate. Example E217: The use of any one of Examples E196-216, wherein the liquid carrier comprises glycerol, propylene glycol, trimethylene glycol, water, ethanol, or combinations thereof. Example E218: The use of any one of Examples E196-216, wherein the liquid carrier comprises propylene glycol and vegetable glycerin. Example E219: The use of any one of Examples E196-216, wherein the liquid carrier comprises 20% to 50% propylene glycol and 80% to 50% vegetable glycerin. Example E220: The use of any one of Examples E196-216, wherein the liquid carrier comprises 30% propylene glycol and 70% vegetable glycerin. Example E221: The use of any one of Examples E196-220, wherein the nicotine salt is in an amount that forms from about 0.5% to about 20% of the nicotine in the inhalable aerosol. Example E222: The use of any one of Examples E196-220, wherein the nicotine salt is in an amount that forms from about 1% to about 20% of the nicotine in the inhalable aerosol. Example E223: The use of any one of Examples E196-222, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 25% (w / w). Example E224: The use of any one of Examples E196-222, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 20% (w / w). Example E225: The use of any one of Examples E196-222, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 18% (w / w). Example E226: The use of any one of Examples E196-222, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 15% (w / w). Example E227: The use of any one of Examples E196-222, wherein the liquid formulation has a nicotine concentration of from about 4% (w / w) to about 12% (w / w). Example E228: The use of any one of Examples E196-222, wherein the liquid formulation has a nicotine concentration of about 4% (w / w). Example E229: The use of any one of Examples E196-222, wherein the liquid formulation has a nicotine concentration of about 2% (w / w). Example E230: The use of any one of examples E196-229, wherein the formulation further comprises a flavouring. Example E231: The use of any one of Examples E196-230, wherein the formulation is non-corrosive to an electronic cigarette. Example E232: The use of any one of Examples E196-231, wherein the acid is stable at and below operating temperature or about 200°C. Example E233: The use of any one of Examples E196-232, wherein the acid does not decompose at or below operating temperature or about 200°C. Example E234: The use of any one of Examples E196-233, wherein the acid does not oxidize at or below operating temperature or about 200°C. Example E235: The use of any one of examples E196-234, where the formulation is not corrosive to the electronic cigarette. Example E236: The use of any one of Examples E196-235, wherein the formulation is non-toxic to an electronic cigarette user. Example E237: The use of any one of Examples E196-236, wherein the formulation further comprises one or more additional nicotine salts in a biologically acceptable liquid carrier suitable for generating the inhalable aerosol upon heating. Example E238: The use of Example E237, wherein a 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. Example E239: A cartomizer for an electronic cigarette comprising: a liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is characterized by a vapor pressure of >20 mmHg at 200°C; an atomizer comprising a heating element in fluid communication with the liquid nicotine salt formulation; Y a fluid storage compartment that stores the liquid nicotine salt formulation. Example E240: A cartomizer for an electronic cigarette comprising: a liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is characterized by a vapor pressure of from about 20 to 200 mmHg at 200°C; an atomizer comprising a heating element in fluid communication with the liquid nicotine salt formulation; Y a fluid storage compartment that stores the liquid nicotine salt formulation. Example E241: A cartomizer for an electronic cigarette comprising: a liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is further characterized by a melting point <1602C, a boiling point >1602C, and at minus a difference of 50°C degrees between the melting point and the boiling point; an atomizer comprising a heating element in fluid communication with the liquid nicotine salt formulation; Y a fluid storage compartment that stores the liquid nicotine salt formulation. Example E242: A cartomizer for an electronic cigarette comprising: a liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is further characterized by a melting point at least 40 degrees lower than the operating temperature of the cigarette electronic, a boiling point not more than 40 degrees lower than the operating temperature of the electronic cigarette, and at least a 50 degree difference between the melting point and the boiling point; an atomizer comprising a heating element in fluid communication with the liquid nicotine salt formulation; Y a fluid storage compartment that stores the liquid nicotine salt formulation. Example E243: The cartomizer of any one of Examples E239-241, wherein the electronic cigarette heats the nicotine salt formulation to an operating temperature of from 150°C to 250°C. Example E244: The cartomizer of any one of Examples E239-241, wherein the electronic cigarette heats the nicotine salt formulation to an operating temperature of from 180°C to 220°C. Example E245: The cartomizer of any one of Examples E239-241, wherein the electronic cigarette heats the nicotine salt formulation to an operating temperature of about 200°C. Example E246: The cartomizer of example E242, where the operating temperature is from 150°C to 250°C. Example E247: The cartomizer of example E242, where the operating temperature is from 180°C to 220°C. Example E248: The cartomizer of example E242, where the operating temperature is about 200°C. Example E249: The cartomizer of any one of examples E239-248, wherein the cartomizer further comprises a mouthpiece. Example E250: The cartomizer of any one of Examples E239-249, wherein an acid used to form the nicotine salt is benzoic acid. Example E251: The cartomizer of any one of examples E239-249, wherein said nicotine salt comprises nicotine benzoate. Example E252: The cartomizer of any one of Examples E239-251, wherein the liquid carrier comprises glycerol, propylene glycol, trimethylene glycol, water, ethanol, or combinations thereof. Example E253: The cartomizer of any one of Examples E239-251, wherein the liquid carrier comprises propylene glycol and vegetable glycerin. Example E254: The cartomizer of any one of Examples E239-251, wherein the liquid carrier comprises 20% to 50% propylene glycol and 80% to 50% vegetable glycerin. Example E255: The cartomizer of any one of Examples E239-251, wherein the liquid carrier comprises 30% propylene glycol and 70% vegetable glycerin. Example E256: The cartomizer of any one of Examples E239-255, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 25% (w / w). Example E257: The cartomizer of any one of Examples E239-255, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 20% (w / w). Example E258: The cartomizer of any one of Examples E239-255, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 18% (w / w). Example E259: The cartomizer of any one of Examples E239-255, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 15% (w / w). Example E260: The cartomizer of any one of Examples E239-255, wherein the liquid formulation has a nicotine concentration of from about 4% (w / w) to about 12% (w / w). Example E261: The cartomizer of any one of examples E239-255, wherein the liquid formulation has a nicotine concentration of approximately 4% (w / w). Example E262: The cartomizer of any one of examples E239-255, wherein the liquid formulation has a nicotine concentration of approximately 2% (w / w). Example E263: The cartomizer of any one of Examples E239-262, wherein the electronic cigarette is configured to generate an aerosol inhalable by a user. Example E264: The cartomizer of example E263, wherein the aerosol comprises a nicotine salt condensate. Example E265: The cartomizer of example E263, wherein the aerosol comprises nicotine free base condensate. Example E266: The cartomizer of example E263, wherein the aerosol comprises nicotine free base condensate and carrier condensate. Example E267: The cartomizer of example E263, wherein the aerosol comprises nicotine free base condensate and acid condensate. Example E268: The cartomizer of any one of Examples E263-267, wherein the aerosol comprises condensate in particle sizes from about 0.1 microns to about 5 microns. Example E269: The cartomizer of any one of Examples E263-267, wherein the aerosol comprises condensate in particle sizes of from about 0.1 microns to about 1 or 2 microns. Example E270: The cartomizer of any one of Examples E263-267, wherein the aerosol comprises condensate in particle sizes from about 0.1 microns to about 0.7 microns. Example E271: The cartomizer of any one of Examples E263-267, wherein the aerosol comprises condensate in particle sizes from about 0.3 microns to about 0.4 microns. Example E272: The cartomizer of any one of Examples E263-271, wherein the nicotine salt is in an amount that forms from about 0.5% to about 20% of the nicotine in the inhalable aerosol. Example E273: The cartomizer of any one of Examples E263-271, wherein the nicotine salt is in an amount that forms from about 1% to about 20% of the nicotine in the inhalable aerosol. Example E274: The cartomizer of any one of the examples E263-273, wherein the formulation further comprises a flavoring agent. Example E275: The cartomizer of any one of Examples E263-274, wherein the formulation is non-corrosive to an electronic cigarette. Example E276: The cartomizer of any one of Examples E263-275, wherein the acid is stable at and below operating temperature or about 200°C. Example E277: The cartomizer of any one of Examples E263-276, wherein the acid does not decompose at or below operating temperature or about 200°C. Example E278: The cartomizer of any one of Examples E263-277, wherein the acid does not oxidize at or below operating temperature or about 200°C. Example E279: The cartomizer of any one of the examples E263-278, where the formulation is not corrosive to the electronic cigarette. Example E280: The cartomizer of any one of Examples E263-279, wherein the formulation is non-toxic to an electronic cigarette user. Example E281: The cartomizer of any one of Examples E263-280, wherein the formulation further comprises one or more additional nicotine salts in a biologically acceptable liquid carrier suitable for generating the inhalable aerosol upon heating. Example E282: The cartomizer of Example E281, wherein a 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. Example E283: An electronic cigarette to generate an inhalable aerosol comprising: a fluid storage compartment; a heater; Y a liquid nicotine salt formulation in the fluid storage compartment, the liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is characterized by a vapor pressure >20 mmHg at 200°C; A battery; Y a mouthpiece. Example E284: An electronic cigarette to generate an inhalable aerosol comprising: a fluid storage compartment; a heater; Y a liquid nicotine salt formulation in the fluid storage compartment, the liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is characterized by a vapor pressure of about 20 at 200mmHg at 200°C; A battery; Y a mouthpiece. Example E285: An electronic cigarette to generate an inhalable aerosol comprising: a fluid storage compartment; a heater; Y a liquid nicotine salt formulation in the fluid storage compartment, the liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is further characterized by a melting point <160 °C, a boiling point >160°C, and at least a 50 degree difference between the melting point and the boiling point; A battery; Y a mouthpiece. Example E286: An electronic cigarette to generate an inhalable aerosol comprising: a fluid storage compartment; a heater; Y a liquid nicotine salt formulation in the fluid storage compartment, the liquid formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is further characterized by a melting point of at least 40 degrees lower than the operating temperature of the electronic cigarette, a boiling point not more than 40 degrees lower than the operating temperature of the electronic cigarette, and a difference of at least 50 degrees between the melting point and the boiling point; A battery; Y a mouthpiece. Example E287: The electronic cigarette of any one of Examples E283-286, wherein the heater comprises a heater chamber, a fluid wick, and a resistive heating element in contact with the fluid wick. Example E288: The electronic cigarette of any one of Examples E283-286, wherein the mouthpiece, heater, and fluid storage compartment form a cartomizer separable from the battery. Example E289: The electronic cigarette of any one of Examples E283-286, wherein the heater and fluid storage compartment form a cartomizer separable from the battery and mouthpiece. Example E290: The electronic cigarette of any one of Examples E283-286, wherein the fluid storage compartment is separable from the heater, battery, and mouthpiece. Example E291: The electronic cigarette of any one of Examples E283-285, wherein the electronic cigarette heats the nicotine salt formulation to an operating temperature of from 150°C to 250°C. Example E292: The electronic cigarette of any one of Examples E283-285, wherein the electronic cigarette heats the nicotine salt formulation to an operating temperature of from 180°C to 220°C. Example E293: The electronic cigarette of any one of Examples E283-285, wherein the electronic cigarette heats the nicotine salt formulation to an operating temperature of about 200°C. Example E294: The electronic cigarette of example E286, wherein the operating temperature is from 150°C to 2502C. Example E295: The electronic cigarette of example E286, wherein the operating temperature is from 180°C to 220°C. Example E296: The electronic cigarette of example E286, wherein the operating temperature is about 200°C. Example E297: The electronic cigarette of any one of examples E283-296, wherein the aerosol comprises nicotine salt condensate. Example E298: The electronic cigarette of any one of Examples E283-296, wherein the aerosol comprises a nicotine free base condensate. Example E299: The electronic cigarette of any one of Examples E283-296, wherein the aerosol comprises nicotine free base condensate and carrier condensate. Example E300: The electronic cigarette of any one of Examples E283-296, wherein the aerosol comprises nicotine free base condensate and acid condensate. Example E301: The electronic cigarette of any one of Examples E283-300, wherein the aerosol comprises condensate in particle sizes from about 0.1 microns to about 5 microns. Example E302: The electronic cigarette of any one of Examples E283-300, wherein the aerosol comprises condensate in particle sizes from about 0.1 microns to about 1 or 2 microns. Example E303: The electronic cigarette of any one of Examples E283-300, wherein the aerosol comprises condensate in particle sizes from about 0.1 microns to about 0.7 microns. Example E304: The electronic cigarette of any one of Examples E283-300, wherein the aerosol comprises condensate in particle sizes from about 0.3 microns to about 0.4 microns. Example E305: The electronic cigarette of any one of Examples E283-304, wherein the acid used to form the nicotine salt is benzoic acid. Example E306: The electronic cigarette of any one of the examples E283-304, wherein said nicotine salt comprises nicotine benzoate. Example E307: The electronic cigarette of any one of Examples E283-306, wherein the liquid carrier comprises glycerol, propylene glycol, trimethylene glycol, water, ethanol, or combinations thereof. Example E308: The electronic cigarette of any one of Examples E283-306, wherein the liquid carrier comprises propylene glycol and vegetable glycerin. Example E309: The electronic cigarette of any one of Examples E283-306, wherein the liquid carrier comprises 20% to 50% propylene glycol and 80% to 50% vegetable glycerin. Example E310: The electronic cigarette of any one of Examples E283-306, wherein the liquid carrier comprises 30% propylene glycol and 70% vegetable glycerin. Example E311: The electronic cigarette of any one of Examples E283-310, wherein the nicotine salt is in an amount that forms from about 0.5% to about 20% of the nicotine in the inhalable aerosol. Example E312: The electronic cigarette of any one of Examples E283-310, wherein the nicotine salt is in an amount that forms from about 1% to about 20% of the nicotine in the inhalable aerosol. Example E313: The electronic cigarette of any one of Examples E283-312, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 25% (w / w). Example E314: The electronic cigarette of any one of Examples E283-312, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 20% (w / w). Example E315: The electronic cigarette of any one of Examples E283-312, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 18% (w / w). Example E316: The electronic cigarette of any one of Examples E283-312, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 15% (w / w). Example E317: The electronic cigarette of any one of Examples E283-312, wherein the liquid formulation has a nicotine concentration of from about 4% (w / w) to about 12% (w / w). Example E318: The electronic cigarette of any one of the examples E283-312, wherein the liquid formulation has a nicotine concentration of approximately 4% (w / w). Example E319: The electronic cigarette of any one of the examples E283-312, wherein the liquid formulation has a nicotine concentration of approximately 2% (w / w). Example E320: The electronic cigarette of any one of the examples E283-319, where the formulation further comprises a flavoring agent. Example E321: The electronic cigarette of any one of Examples E283-320, wherein the formulation is non-corrosive to an electronic cigarette. Example E322: The electronic cigarette of any one of Examples E283-321, wherein the acid is stable at and below operating temperature or about 200°C. Example E323: The electronic cigarette of any one of Examples E283-322, wherein the acid does not decompose at or below operating temperature or about 200°C. Example E324: The electronic cigarette of any one of Examples E283-323, wherein the acid does not oxidize at or below operating temperature or about 200°C. Example E325: The electronic cigarette of any one of examples E283-324, wherein the formulation is not corrosive to the electronic cigarette. Example E326: The electronic cigarette of any one of Examples E283-325, wherein the formulation is non-toxic to a user of the electronic cigarette. Example E327: The electronic cigarette of any one of Examples E283-326, wherein the formulation further comprises one or more additional nicotine salts in a biologically acceptable liquid carrier suitable for generating the inhalable aerosol upon heating. Example E328: The electronic cigarette of Example E327, wherein a 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. Example E329: A cartridge in an electronic cigarette comprising a fluid storage compartment, wherein the fluid storage compartment stores a liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is characterized by a vapor pressure >20 mmHg at 200°C. Example E330: A cartridge in an electronic cigarette comprising a fluid storage compartment, wherein the fluid storage compartment stores a liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is characterized by a vapor pressure of about 20 to 200 mmHg at 200°C. Example E331: A cartridge in an electronic cigarette comprising a fluid storage compartment, wherein the fluid storage compartment stores a liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is further characterized by a melting point <1602C, a boiling point >1602C, and at least a 50 degree difference between the melting point and the boiling point. Example E332: A cartridge in an electronic cigarette comprising a fluid storage compartment, wherein the fluid storage compartment stores a liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is further characterized by a melting point at least 40 degrees lower than the operating temperature of the electronic cigarette, a boiling point not more than 40 degrees lower than the operating temperature of the electronic cigarette, and at minus a difference of 50 degrees between the melting point and the boiling point. Example E333: The cartridge of any one of Examples E329-332, wherein the cartridge is separable from the electronic cigarette. Example E334: The cartridge of any one of Examples E329-333, wherein an acid used to form the nicotine salt is benzoic acid. Example E335: The cartridge of any one of Examples E329-333, wherein said nicotine salt comprises nicotine benzoate. Example E336: The cartridge of any one of Examples E329-335, wherein the liquid carrier comprises glycerol, propylene glycol, trimethylene glycol, water, ethanol, or combinations thereof. Example E337: The cartridge of any one of Examples E329-335, wherein the liquid carrier comprises propylene glycol and vegetable glycerin. Example E338: The cartridge of any one of Examples E329-335, wherein the liquid carrier comprises 20% to 50% propylene glycol and 80% to 50% vegetable glycerin. Example E339: The cartridge of any one of Examples E329-335, wherein the liquid carrier comprises 30% propylene glycol and 70% vegetable glycerin. Example E340: The cartridge of any one of Examples E329-339, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 25% (w / w). Example E341: The cartridge of any one of Examples E329-339, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 20% (w / w). Example E342: The cartridge of any one of Examples E329-339, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 18% (w / w). Example E343: The cartridge of any one of Examples E329-339, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 15% (w / w). Example E344: The cartridge of any one of Examples E329-339, wherein the liquid formulation has a nicotine concentration of from about 4% (w / w) to about 12% (w / w). Example E345: The cartridge of any one of Examples E329-339, wherein the liquid formulation has a nicotine concentration of approximately 4% (w / w). Example E346: The cartridge of any one of Examples E329-339, wherein the liquid formulation has a nicotine concentration of approximately 2% (w / w). Example E347: The cartridge of any one of examples E329-346, wherein the formulation further comprises a flavoring agent. Example E348: The cartridge of any one of Examples E329-347, wherein the formulation is non-corrosive to an electronic cigarette. Example E349: The cartridge of any one of Examples E329-348, wherein the acid is stable at and below operating temperature or about 200°C. Example E350: The cartridge of any one of Examples E329-349, wherein the acid does not decompose at or below operating temperature or about 200°C. Example E351: The cartridge of any one of Examples E329-350, wherein the acid does not oxidize at or below operating temperature or about 200°C. Example E352: The cartridge of any one of the examples E329-351, where the formulation is not corrosive to the electronic cigarette. Example E353: The cartridge of any one of Examples E329-352, wherein the formulation is non-toxic to an electronic cigarette user. Example E354: The cartridge of any one of Examples E329-353, wherein the formulation further comprises one or more additional nicotine salts in a biologically acceptable liquid carrier suitable for generating the inhalable aerosol upon heating. Example E355: The cartridge of Example E354, wherein a 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. Example E356: A kit comprising: (a) an electronic cigarette for generating an inhalable aerosol comprising Yo. a device body comprising a cartridge receptacle; ii. a cartridge comprising a fluid storage compartment, wherein the fluid storage compartment stores a liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt characterized by a vapor pressure >20 mmHg at 200°C; iii. a heater; IV. A battery; Y v. a mouthpiece; Y (b) instructions for using the electronic cigarette to generate an inhalable aerosol. Example E357: A kit comprising: (a) an electronic cigarette for generating an inhalable aerosol comprising Yo. a device body comprising a cartridge receptacle; ii. a cartridge comprising a fluid storage compartment, wherein the fluid storage compartment stores a liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt it is characterized by a vapor pressure of about 20 to 200 mmHg at 200°C; iii. a heater; IV. A battery; Y v. a mouthpiece; Y (b) instructions for using the electronic cigarette to generate an inhalable aerosol. Example E358: A kit comprising: (a) an electronic cigarette for generating an inhalable aerosol comprising Yo. a device body comprising a cartridge receptacle; ii. a cartridge comprising a fluid storage compartment, wherein the fluid storage compartment stores a liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt it is further characterized by a melting point <160°C, a boiling point >160°C, and a difference of at least 50 degrees between the melting point and the boiling point; iii. a heater; IV. A battery; Y v. a mouthpiece; Y (b) instructions for using the electronic cigarette to generate an inhalable aerosol. Example E359: A kit comprising: (a) an electronic cigarette for generating an inhalable aerosol comprising Yo. a device body comprising a cartridge receptacle; ii. a cartridge comprising a fluid storage compartment, wherein the fluid storage compartment stores a liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is further characterized by a melting point at least 40 degrees lower than the operating temperature of the electronic cigarette, a boiling point not more than 40 degrees lower than the operating temperature of the electronic cigarette, and at least a 50 degree difference between the melting point and the boiling point; iii. a heater; IV. A battery; Y v. a mouthpiece; Y (b) instructions for using the electronic cigarette to generate an inhalable aerosol. Example E360: The kit of any one of Examples E356-359, wherein the acid used to form the nicotine salt is benzoic acid. Example E361: The kit of any one of examples E356-359, wherein said nicotine salt comprises nicotine benzoate. Example E362: The kit of any one of Examples E356-361, wherein the liquid carrier comprises glycerol, propylene glycol, trimethylene glycol, water, ethanol, or combinations thereof. Example E363: The kit of any one of Examples E356-361, wherein the liquid carrier comprises propylene glycol and vegetable glycerin. Example E364: The kit of any one of Examples E356-361, wherein the liquid carrier comprises 20% to 50% propylene glycol and 80% to 50% vegetable glycerin. Example E365: The kit of any one of Examples E356-361, wherein the liquid carrier comprises 30% propylene glycol and 70% vegetable glycerin. Example E366: The kit of any one of Examples E356-365, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 25% (w / w). Example E367: The kit of any one of Examples E356-365, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 20% (w / w). Example E368: The kit of any one of Examples E356-365, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 18% (w / w). Example E369: The kit of any one of Examples E356-365, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 15% (w / w). Example E370: The kit of any one of Examples E356-365, wherein the liquid formulation has a nicotine concentration of from about 4% (w / w) to about 12% (w / w). Example E371: The kit of any one of examples E356-365, wherein the liquid formulation has a nicotine concentration of approximately 4% (w / w). Example E372: The kit of any one of Examples E356-365, wherein the liquid formulation has a nicotine concentration of approximately 2% (w / w). Example E373: The kit of any one of examples E356-372, wherein the formulation further comprises a flavoring agent. Example E374: The kit of any one of Examples E356-373, wherein the formulation is non-corrosive to an electronic cigarette. Example E375: The kit of any one of Examples E356-374, wherein the acid is stable at and below operating temperature or about 200°C. Example E376: The kit of any one of Examples E356-375, wherein the acid does not decompose at or below operating temperature or about 200°C. Example E377: The kit of any one of Examples E356-376, wherein the acid does not oxidize at or below operating temperature or about 200°C. Example E378: The kit of any one of the examples E356-377, where the formulation is not corrosive to the electronic cigarette. Example E379: The kit of any one of Examples E356-378, wherein the formulation is non-toxic to an electronic cigarette user. Example E380: The kit of any one of Examples E356-379, wherein the formulation further comprises one or more additional nicotine salts in a biologically acceptable liquid carrier suitable for generating the inhalable aerosol upon heating. Example E381: The kit of Example E380, wherein a 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. Example E382: A cartridge comprising a fluid storage compartment, wherein the fluid storage compartment stores a liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is characterized by a vapor pressure >20 mmHg at 200°C. Example E383: A cartridge comprising a fluid storage compartment, wherein the fluid storage compartment stores a liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said Nicotine salt is characterized by a vapor pressure of approximately 20 to 200 mmHg at 200°C. Example E384: A cartridge comprising a fluid storage compartment, wherein the fluid storage compartment stores a liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is further characterized by a melting point <160°C, a boiling point >160°C, and at least a 50 degree difference between the melting point and the boiling point. Example E385: A cartridge comprising a fluid storage compartment, wherein the fluid storage compartment stores a liquid nicotine salt formulation comprising a nicotine salt in a biologically acceptable liquid carrier wherein an acid used to form said nicotine salt is further characterized by a melting point at least 40 degrees lower than the operating temperature of the electronic cigarette, a boiling point not more than 40 degrees lower than the operating temperature of the electronic cigarette, and at least a difference of 50 degrees between the melting point and the boiling point. Example E386: The cartridge of any one of Examples E383-385, wherein the cartridge is connectable to an electronic cigarette. Example E387: The cartridge of any one of Examples E383-386, wherein the acid used to form the nicotine salt is benzoic acid. Example E388: The cartridge of any one of examples E383-386, wherein said nicotine salt comprises nicotine benzoate. Example E389: The cartridge of any one of Examples E383-388, wherein the liquid carrier comprises glycerol, propylene glycol, trimethylene glycol, water, ethanol, or combinations thereof. Example E390: The cartridge of any one of Examples E383-388, wherein the liquid carrier comprises propylene glycol and vegetable glycerin. Example E391: The cartridge of any one of Examples E383-388, wherein the liquid carrier comprises 20% to 50% propylene glycol and 80% to 50% vegetable glycerin. Example E392: The cartridge of any one of Examples E383-388, wherein the liquid carrier comprises 30% propylene glycol and 70% vegetable glycerin. Example E393: The cartridge of any one of Examples E383-392, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 25% (w / w). Example E394: The cartridge of any one of Examples E383-392, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 20% (w / w). Example E395: The cartridge of any one of Examples E383-392, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 18% (w / w). Example E396: The cartridge of any one of Examples E383-392, wherein the liquid formulation has a nicotine concentration of from about 1% (w / w) to about 15% (w / w). Example E397: The cartridge of any one of Examples E383-392, wherein the liquid formulation has a nicotine concentration of from about 4% (w / w) to about 12% (w / w). Example E398: The cartridge of any one of Examples E383-392, wherein the liquid formulation has a nicotine concentration of approximately 4% (w / w). Example E399: The cartridge of any one of Examples E383-392, wherein the liquid formulation has a nicotine concentration of approximately 2% (w / w). Example E400: The cartridge of any one of Examples E383-399, wherein the formulation further comprises a flavoring agent. Example E401: The cartridge of any one of Examples E383-400, wherein the formulation is non-corrosive to an electronic cigarette. Example E402: The cartridge of any one of Examples E383-401, wherein the acid is stable at and below operating temperature or about 200°C. Example E403: The cartridge of any one of Examples E383-402, wherein the acid does not decompose at or below operating temperature or about 200°C. Example E404: The cartridge of any one of Examples E383-403, wherein the acid does not oxidize at or below operating temperature or about 200°C. Example E405: The cartridge of any one of the examples E383-404, where the formulation is not corrosive to the electronic cigarette. Example E406: The cartridge of any one of Examples E383-405, wherein the formulation is non-toxic to an electronic cigarette user. Example E407: The cartridge of any one of Examples E383-406, wherein the formulation further comprises one or more additional nicotine salts in a biologically acceptable liquid carrier suitable for generating the inhalable aerosol upon heating. Example E408: The cartridge of Example E407, wherein a 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.

Claims

1. An electronic cigarette for generating an inhalable aerosol comprising: a liquid nicotine salt formulation comprising at least one nicotine salt, the at least one nicotine salt comprising a nicotine salt and benzoic acid in a biologically acceptable liquid carrier, wherein the at least one nicotine salt in the liquid nicotine salt formulation is present in an amount forming from 0.5% (w / w) to 20% (w / w) of nicotine in the inhalable aerosol; and the molar ratio of benzoic acid to nicotine in the liquid nicotine salt formulation is 1:

1.

2. The electronic cigarette of claim 1, wherein the concentration of nicotine salt in the liquid nicotine salt formulation is from 0.5% (w / w) to 20% (w / w), optionally from 1% (w / w) to 20% (w / w), optionally from 1% (w / w) to 18% (w / w), optionally from 1% (w / w) to 15% (w / w), optionally from 4% (w / w) to 12% (w / w). 3.The electronic cigarette of claim 1 or 2, wherein the liquid nicotine salt formulation is contained in a cartridge configured to serve as a mouthpiece and reservoir for the liquid nicotine salt formulation.

4. The electronic cigarette of claim 3, further comprising an atomizer configured to vaporize the liquid nicotine salt formulation, and a battery.

5. The electronic cigarette of any one of claims 1 to 4, wherein the liquid carrier comprises glycerol and propylene glycol.

6. The electronic cigarette of any one of claims 1 to 5, wherein the liquid nicotine salt formulation further comprises a flavoring agent. 7.A method for delivering nicotine to an electronic cigarette user, the method comprising: heating a liquid nicotine salt formulation in an electronic cigarette to produce an inhalable aerosol, wherein the liquid nicotine salt formulation comprises at least one nicotine salt, the at least one nicotine salt comprising a nicotine salt and benzoic acid in a biologically acceptable liquid carrier, wherein the at least one nicotine salt in the liquid nicotine salt formulation is present in an amount forming from 0.5% (w / w) to 20% (w / w) of nicotine in the inhalable aerosol; and the molar ratio of benzoic acid to nicotine in the liquid nicotine salt formulation is 1:

1. 8.The method of claim 7, wherein the concentration of nicotine salt in the liquid nicotine salt formulation is from 0.5% (w / w) to 20% (w / w), optionally from 1% (w / w) to 20% (w / w), optionally from 1% (w / w) to 18% (w / w), optionally from 1% (w / w) to 15% (w / w), or optionally from 4% (w / w) to 12% (w / w).

9. The method of claim 7 or 8, wherein the electronic cigarette comprises a cartridge, and the cartridge is configured to serve as a mouthpiece and reservoir containing the liquid nicotine salt formulation.

10. The method of claim 9, wherein the electronic cigarette further comprises an atomizer configured to vaporize the liquid nicotine salt formulation, and a battery.

11. The cartridge of any one of claims 7 to 10, wherein the liquid carrier comprises glycerol and propylene glycol. 12.The method of any one of claims 7 to 11, wherein the liquid nicotine salt formulation further comprises a flavoring agent.