LIQUID NICOTINE FORMULATION COMPRISING A SOLVENT PARTIALLY SOLUBLE IN WATER.

Abstract

A liquid nicotine formulation for use in an aerosol generating system, the liquid nicotine formulation comprising: water; and one or more partially water-soluble, water-immiscible solvents having a water solubility at 20°C of between approximately 20 mg / ml and approximately 100 mg / ml, wherein the liquid nicotine formulation has a water content greater than or equal to approximately 5 percent by weight and a partially water-soluble, water-immiscible solvent content greater than or equal to approximately 2 percent by weight. A liquid nicotine formulation for use in an aerosol generating system, the liquid nicotine formulation comprising: water; and one or more partially water-soluble, water-immiscible solvents having a partition coefficient (log P) at 20°C of between approximately 0.05 and approximately 0.5, wherein the liquid nicotine formulation has a water content greater than or equal to approximately 5 percent by weight and a partially water-soluble solvent content, immiscible in water, greater than or equal to approximately 2 percent by weight. A cartridge for use in an aerosol generating system, the cartridge containing the liquid nicotine formulation. An aerosol generating system comprising the liquid nicotine formulation and an atomizer configured to generate an aerosol from the liquid nicotine formulation.

Description

LIQUID NICOTINE FORMULATION COMPRISING A PARTIALLY WATER-SOLUBLE SOLVENT FIELD OF INVENTION The invention relates to a liquid nicotine formulation for use in an aerosol generating system. The invention also relates to a cartridge for an aerosol generating system comprising the liquid nicotine formulation and an aerosol generating system comprising the liquid nicotine formulation and an atomizer configured to generate an aerosol from the liquid nicotine formulation. BACKGROUND OF THE INVENTION Aerosol generating systems for delivering nicotine to a user are known to comprise an atomizer configured to generate an inhalable aerosol from a liquid nicotine formulation. Some known aerosol generating systems comprise a thermal atomizer, such as an electric heater, configured to heat and vaporize the liquid nicotine formulation to generate an aerosol. Other known aerosol generating systems comprise a non-thermal atomizer configured to generate an aerosol from the liquid nicotine formulation using, for example, impact jet, ultrasonic, or vibrating mesh technologies. Typical liquid nicotine formulations for use in aerosol generating systems comprise glycerin, propylene glycol, and water as solvents. In such aerosol-generating systems, the pulmonary delivery of the inhalable aerosol generated from the liquid nicotine formulation is important for palatability and user satisfaction. Nicotine adsorption through the pulmonary alveoli is rapid and efficient. Conversely, nicotine adsorption in the upper respiratory tract is slower and less efficient. Nicotine adsorption in the upper respiratory tract can also be perceived as unpleasant by a user with sensitive taste and induce irritation of the mouth and throat. It would be advantageous to provide a liquid nicotine formulation for use in an aerosol generating system that produces an aerosol offering improved nicotine satisfaction to the user compared to typical liquid nicotine formulations. Specifically, it would be advantageous to provide a liquid nicotine formulation for use in an aerosol generating system that produces an aerosol with improved nicotine deposition and pulmonary retention characteristics compared to aerosols generated from typical liquid nicotine formulations. BRIEF DESCRIPTION OF THE INVENTION According to a first aspect of the invention, a liquid nicotine formulation is provided for use in an aerosol generating system, the liquid nicotine formulation comprising: at least one water and one or more water-miscible solvents; and one or more partially water-soluble, water-immiscible solvents having a water solubility at 20°C of between approximately 20 mg / ml and approximately 100 mg / ml, wherein the liquid nicotine formulation has a water-soluble, water-immiscible solvent content greater than or equal to approximately 2 percent by weight. In accordance with the first aspect of the invention, a cartridge is also provided for use in an aerosol generating system, the cartridge containing a liquid nicotine formulation comprising: at least one water and one or more water-miscible solvents; and one or more partially water-soluble, water-immiscible solvents having a water solubility at 20°C of between approximately 20 mg / ml and approximately 100 mg / ml, wherein the liquid nicotine formulation has a water-soluble, water-immiscible solvent content greater than or equal to approximately 2 percent by weight. c^aynn / i ζηζ / E / γ In accordance with the first aspect of the invention, an aerosol generating system is further provided comprising: a liquid nicotine formulation comprising: at least one water and one or more water-miscible solvents; and one or more partially water-soluble, water-immiscible solvents having a water solubility at 20°C of between approximately 20 mg / ml and approximately 100 mg / ml, wherein the liquid nicotine formulation has a partially water-soluble, water-immiscible solvent content greater than or equal to approximately 2 percent by weight; and an atomizer configured to generate an aerosol from the liquid nicotine formulation. According to a second aspect of the invention, a liquid nicotine formulation is provided for use in an aerosol generating system, the liquid nicotine formulation comprising: at least one water and one or more water-miscible solvents; and one or more partially water-soluble, water-immiscible solvents having a partition coefficient (log P) at 20 °C of between approximately 0.05 and approximately 0.5, wherein the liquid nicotine formulation has a water-soluble, water-immiscible solvent content greater than or equal to approximately 2 percent by weight. In accordance with the second aspect of the invention, a cartridge is also provided for use in an aerosol generating system, the cartridge containing a liquid nicotine formulation comprising: at least one water and one or more water-miscible solvents; and one or more partially water-soluble, water-immiscible solvents having a partition coefficient (log P) at 20 °C of between approximately 0.05 and approximately 0.5, wherein the liquid nicotine formulation has a water-soluble, water-immiscible solvent content greater than or equal to approximately 2 percent by weight. In accordance with the second aspect of the invention, an aerosol generating system is further provided comprising: a liquid nicotine formulation comprising: at least one water and one or more water-miscible solvents; and one or more partially water-soluble, water-immiscible solvents having a partition coefficient (log P) at 20 °C of czaynn / i ζηζ / E / γ between approximately 0.05 and approximately 0.5, wherein the liquid nicotine formulation has a partially water-soluble, water-immiscible solvent content greater than or equal to approximately 2 percent by weight; and an atomizer configured to generate an aerosol from the liquid nicotine formulation. As used herein with reference to the invention, the term “liquid nicotine formulation” describes a liquid formulation comprising nicotine. As used herein with reference to the invention, the term “nicotine” describes nicotine, nicotine base, or a nicotine salt. In embodiments where the liquid nicotine formulation comprises a nicotine base or a nicotine salt, the amounts of nicotine referred to herein are the amount of nicotine base or the amount of protonated nicotine, respectively. As used herein with reference to the invention, the term “water miscible solvent” describes a compound other than water or an organic acid that is liquid at 20 °C and mixes with water in all proportions to form a homogeneous solution. As used herein with reference to the first aspect of the invention, the term “water-partially soluble, water-immiscible solvent” describes a compound that is liquid at 20 °C and has a solubility in water at 20 °C of between approximately 20 mg / ml and approximately 100 mg / ml. As used herein with reference to the second aspect of the invention, the term “water-partially soluble solvent, immiscible in water” describes a compound that is liquid at 20 °C and has a partition coefficient (log P) at 20 °C of between approximately 0.05 and approximately 0.5. Unless otherwise stated, the water solubility values ​​quoted herein are the water solubility measured on the basis of the OECD Preliminary Test (1995), Test No. 105: Water Solubility, OECD Guidelines for the Testing of Chemicals, Section 1, OECD Publishing, Paris, https: / / doi.org / 10.1787 / 9789264069589-en. In a stepwise procedure, increasing volumes of distilled water at 20 °C are added to 0.1 g of the sample (solid substances must be pulverized) in a 10 ml glass-stoppered graduated cylinder. However, when the substance is an acid, the sample is added to the distilled water in the first step. After each addition of water, the mixture is stirred for 10 minutes and visually checked for undissolved parts of the sample. If, after the addition of 10 ml of water, the sample or parts of it remain undissolved, the experiment is continued in a 100 ml graduated cylinder.The approximate solubility is given in Table 1 below under that volume of water in which complete dissolution of the sample occurs. When solubility is low, it may take a long time to dissolve a substance, and it should be left for at least 24 hours. If, after 24 hours, the substance is still not dissolved, the test tube is placed in an ultrasonic bath at 40 °C for 15 minutes and left for another 24 hours (up to a maximum of 96 hours). If the substance is still not dissolved, its solubility is considered to be below the limit value, or it is considered insoluble. czajnn / i znz / E / YiAi Approximate solubility (mg / ml) in which 0.1 g of the sample is soluble: 0.1 0.5 1 2 10 100 >100 >100 >100 1000 up to 200 200 up to 100 100 up to 50 50 up to 10 10 up to 1 <1 Table 1 Unless otherwise stated, the partition coefficient (log P) values ​​quoted herein are the octanol / water partition coefficient (log Pow) measured in accordance with: OECD (1995), Test No. 107: Partition Coefficient (n-octanol / water): Shake Flask Method, OECD Guidelines for the Testing of Chemicals, Section 1, OECD Publishing, Paris, https: / / doi.org / 10.1787 / 9789264069626-en (for values ​​in the log Pow range between -2 and 4); OECD (2004), Test No. 117: Partition Coefficient (n-octanol / water), HPLC Method, OECD Guidelines for the Testing of Chemicals, Section 1, OECD Publishing, Paris, https: / / doi.org / 10.1787 / 9789264069824-en (for values ​​in the log POw range between 0 and 6); and OECD (2006), Test No. 123: Partition Coefficient (1-Octanol / Water): Slow-Stirring Method, OECD Guidelines for the Testing of Chemicals, Section 1, OECD Publishing, Paris, https: / / doi.org / 10.1787 / 9789264015845-en (for values ​​in the log Pow range up to 8.2). The inclusion of a combination of at least one water and one or more water-miscible solvents and one or more partially water-soluble, water-immiscible solvents in the liquid nicotine formulation according to the invention advantageously allows the generation of an inhalable aerosol that provides improved nicotine satisfaction to a user compared to aerosols generated from typical liquid nicotine formulations. In particular, the inclusion of a combination of at least one water and one or more water-miscible solvents and one or more partially water-soluble, water-immiscible solvents in the liquid nicotine formulation according to the invention advantageously allows the generation of an inhalable aerosol that has improved nicotine deposition and pulmonary retention characteristics compared to aerosols generated from typical liquid nicotine formulations. Due to the inclusion of a combination of at least one water component and one or more water-miscible solvents and one or more partially water-soluble, water-immiscible solvents, when used in an aerosol generating system, the liquid nicotine formulation according to the invention generates an inhalable aerosol comprising dual-phase particles or droplets comprising an aqueous or water-miscible phase and a water-immiscible phase. This advantageously reduces nicotine adsorption in the upper respiratory tract and enhances pulmonary nicotine delivery and retention. Without wishing to be limited by theory, it is believed that the improvement in pulmonary nicotine delivery and retention is due to the coating or enveloping of the aqueous or water-miscible phase by the water-immiscible phase. This is believed to reduce nicotine evaporation and adsorption in the upper respiratory tract. czajnn / i ζηζ / Ε / γ Unless otherwise stated, the weight percentages of the liquid nicotine formulation components quoted in this description are based on the total weight of the liquid nicotine formulation. Liquid nicotine formulations may comprise natural nicotine or synthetic nicotine. Liquid nicotine formulations may have a nicotine content greater than or equal to approximately 0.5 percent by weight. Preferably, the liquid nicotine formulation has a nicotine content greater than or equal to approximately 1 percent by weight. More preferably, the liquid nicotine formulation has a nicotine content greater than or equal to approximately 1.5 percent by weight. The liquid nicotine formulation may have a nicotine content less than or equal to approximately 10 percent by weight. The liquid nicotine formulation may have a nicotine content less than or equal to approximately 8 percent by weight. Preferably, the liquid nicotine formulation has a nicotine content of approximately 5 percent by weight or less. More preferably, the liquid nicotine formulation has a nicotine content of approximately 3 percent by weight or less. The liquid nicotine formulation may have a nicotine content of between approximately 0.5 percent by weight and approximately 10 percent by weight. For example, the liquid nicotine formulation may have a nicotine content of between approximately 0.5 percent by weight and approximately 8 percent by weight, between approximately 0.5 percent by weight and approximately 5 percent by weight, or between approximately 0.5 percent by weight and approximately 3 percent by weight. Preferably, the liquid nicotine formulation has a nicotine content of between approximately 1 percent by weight and approximately 10 percent by weight. For example, the liquid nicotine formulation may have a nicotine content of between approximately 1 percent by weight and approximately 8 percent by weight, between approximately 1 percent by weight and approximately 5 percent by weight, or between approximately 1 percent by weight and approximately 3 percent by weight. Ideally, liquid nicotine formulations have a nicotine content of between approximately 1.5 percent and approximately 10 percent by weight. For example, a liquid nicotine formulation may have a nicotine content of between approximately 1.5 percent and approximately 8 percent by weight, between approximately 1.5 percent and approximately 5 percent by weight, or between approximately 1.5 percent and approximately 3 percent by weight. Liquid nicotine formulations comprise at least water and one or more water-miscible solvents. That is, liquid nicotine comprises water, one or more miscible solvents, or both water and one or more miscible solvents. Preferably, the liquid nicotine formulation has a total water and water-miscible solvent content greater than or equal to approximately 50 percent by weight or greater than or equal to approximately 55 percent by weight. Preferably, the liquid nicotine formulation has a total water and water-miscible solvent content greater than or equal to approximately 60 percent by weight. For example, the liquid nicotine formulation may have a total water and water-miscible solvent content greater than or equal to approximately 65 percent by weight, greater than or equal to approximately 70 percent by weight, greater than or equal to approximately 75 percent by weight, greater than or equal to approximately 80 percent by weight, or greater than or equal to approximately 85 percent by weight. In formulations where the liquid nicotine formulation includes water, the water can advantageously help to dissolve and stabilize the polar and ionic components of the liquid nicotine formulation. In embodiments where the liquid nicotine formulation comprises water, preferably the liquid nicotine formulation has a water content greater than or equal to approximately 10 percent by weight. More preferably, the liquid nicotine formulation has a water content greater than or equal to approximately 10 percent by weight. For example, the liquid nicotine formulation may have a water content greater than or equal to approximately 15 percent by weight, greater than or equal to approximately 20 percent by weight, greater than or equal to approximately 25 percent by weight, greater than or equal to approximately 30 percent by weight, or greater than or equal to approximately 35 percent by weight. In the forms in which the liquid nicotine formulation comprises water, the liquid nicotine formulation may have a water content less than or equal to approximately 90 percent by weight. In embodiments where the liquid nicotine formulation comprises water, preferably the liquid nicotine formulation has a water content of approximately 85 percent by weight or less. More preferably, the liquid nicotine formulation has a water content of approximately 80 percent by weight or less. For example, the liquid nicotine formulation may have a water content of approximately 75 percent by weight or less, approximately 70 percent by weight or less, or approximately 65 percent by weight or less. In embodiments where the liquid nicotine formulation comprises water, the liquid nicotine formulation may have a water content of between approximately 5 percent by weight and approximately 90 percent by weight. Preferably, the liquid nicotine formulation has a water content of between approximately 5 percent by weight and approximately 85 percent by weight. For example, the liquid nicotine formulation may have a water content of between approximately 5 percent by weight and approximately 80 percent by weight, between approximately 5 percent by weight and approximately 75 percent by weight, between approximately 5 percent by weight and approximately 70 percent by weight, or between approximately 5 percent by weight and approximately 65 percent by weight. czaynn / i ζηζ / E / γ Liquid nicotine formulations may have a water content of between approximately 10 percent by weight and approximately 90 percent by weight. More preferably, liquid nicotine formulations have a water content of between approximately 10 percent by weight and approximately 85 percent by weight. For example, liquid nicotine formulations may have a water content of between approximately 10 percent by weight and approximately 80 percent by weight, between approximately 10 percent by weight and approximately 75 percent by weight, between approximately 10 percent by weight and approximately 70 percent by weight, or between approximately 10 percent by weight and approximately 65 percent by weight. In formulations where the liquid nicotine formulation includes water, the liquid nicotine formulation may have a water content of between approximately 15 percent by weight and approximately 90 percent by weight, or between approximately 15 percent by weight and approximately 85 percent by weight. For example, the liquid nicotine formulation may have a water content of between approximately 15 percent by weight and approximately 80 percent by weight, between approximately 15 percent by weight and approximately 75 percent by weight, between approximately 15 percent by weight and approximately 70 percent by weight, or between approximately 15 percent by weight and approximately 65 percent by weight. Liquid nicotine formulations can have a water content of between approximately 20 percent by weight and approximately 90 percent by weight, or between approximately 20 percent by weight and approximately 85 percent by weight. For example, liquid nicotine formulations can have a water content of between approximately 20 percent by weight and approximately 80 percent by weight, between approximately 20 percent by weight and approximately 75 percent by weight, between approximately 20 percent by weight and approximately 70 percent by weight, or between approximately 20 percent by weight and approximately 65 percent by weight. C7Q7nn / l 7Π7 / Β / Y Liquid nicotine formulations can have a water content of between approximately 25 percent by weight and approximately 90 percent by weight, or between approximately 25 percent by weight and approximately 85 percent by weight. For example, liquid nicotine formulations can have a water content of between approximately 25 percent by weight and approximately 80 percent by weight, between approximately 25 percent by weight and approximately 75 percent by weight, between approximately 25 percent by weight and approximately 70 percent by weight, or between approximately 25 percent by weight and approximately 65 percent by weight. Liquid nicotine formulations can have a water content of between approximately 30 percent by weight and approximately 90 percent by weight, or between approximately 30 percent by weight and approximately 85 percent by weight. For example, liquid nicotine formulations can have a water content of between approximately 30 percent by weight and approximately 80 percent by weight, between approximately 30 percent by weight and approximately 75 percent by weight, between approximately 30 percent by weight and approximately 70 percent by weight, or between approximately 30 percent by weight and approximately 65 percent by weight. Liquid nicotine formulations can have a water content of between approximately 35 percent by weight and approximately 90 percent by weight, or between approximately 35 percent by weight and approximately 85 percent by weight. For example, liquid nicotine formulations can have a water content of between approximately 35 percent by weight and approximately 80 percent by weight, between approximately 35 percent by weight and approximately 75 percent by weight, between approximately 35 percent by weight and approximately 70 percent by weight, or between approximately 35 percent by weight and approximately 65 percent by weight. In embodiments where the liquid nicotine formulation comprises one or more water-miscible solvents, the one or more water-miscible solvents can advantageously help to dissolve and stabilize the polar components and ionic components of the liquid nicotine formulation. In embodiments where the liquid nicotine formulation comprises one or more water-miscible solvents, preferably the liquid nicotine formulation has a water-miscible solvent content of approximately 5 percent by weight or greater. More preferably, the liquid nicotine formulation has a water-miscible solvent content of approximately 10 percent by weight or greater. For example, the liquid nicotine formulation may have a water-miscible solvent content of approximately 15 percent by weight or greater, approximately 20 percent by weight or greater, or approximately 25 percent by weight or greater. The liquid nicotine formulation may have a water miscible solvent content less than or equal to approximately 80 percent by weight or less than or equal to approximately 75 percent by weight. In embodiments where the liquid nicotine formulation comprises one or more water-miscible solvents, preferably, the liquid nicotine formulation has a water-miscible solvent content of approximately 70 percent by weight or less. More preferably, the liquid nicotine formulation has a water-miscible solvent content of approximately 60 percent by weight or less. For example, the liquid nicotine formulation may have a water-miscible solvent content of approximately 50 percent by weight or approximately 40 percent by weight or less. In embodiments where the liquid nicotine formulation comprises one or more water-miscible solvents, preferably the liquid nicotine formulation has a water-miscible solvent content of between approximately 5 percent by weight and approximately 70 percent by weight. For example, the liquid nicotine formulation may have a water-miscible solvent content of between approximately 5 percent by weight and approximately 60 percent by weight, between approximately 5 percent by weight and approximately 50 percent by weight, or between approximately 5 percent by weight and approximately 40 percent by weight. Preferably, the liquid nicotine formulation has a water-miscible solvent content of between approximately 10 percent by weight and approximately 70 percent by weight. For example, the liquid nicotine formulation may have a water-miscible solvent content of between approximately 10 percent by weight and approximately 60 percent by weight, between approximately 10 percent by weight and approximately 50 percent by weight, or between approximately 10 percent by weight and approximately 40 percent by weight. In embodiments where the liquid nicotine formulation comprises one or more water-miscible solvents, the liquid nicotine formulation may have a water-miscible solvent content of between approximately 15 percent by weight and approximately 70 percent by weight, between approximately 15 percent by weight and approximately 60 percent by weight, between approximately 15 percent by weight and approximately 50 percent by weight, or between approximately 15 percent by weight and approximately 40 percent by weight. The liquid nicotine formulation may have a water-miscible solvent content of between approximately 20 percent by weight and approximately 70 percent by weight, between approximately 20 percent by weight and approximately 60 percent by weight, between approximately 20 percent by weight and approximately 50 percent by weight, or between approximately 20 percent by weight and approximately 40 percent by weight. The liquid nicotine formulation may have a water-miscible solvent content of between approximately 25 percent by weight and approximately 70 percent by weight, between approximately 25 percent by weight and approximately 60 percent by weight, between approximately 25 percent by weight and approximately 50 percent by weight, or between approximately 25 percent by weight and approximately 40 percent by weight. czaynn / i ζηζ / E / γ In embodiments where the liquid nicotine formulation comprises one or more water-miscible solvents, preferably the one or more water-miscible solvents are one or more water-miscible polyhydric alcohols. As used herein with reference to the invention, the term “water miscible polyhydric alcohol” describes a polyhydric alcohol that is liquid at 20 °C and mixes with water in all proportions to form a homogeneous solution. According to a preferred embodiment of the first aspect of the invention, a liquid nicotine formulation is provided for use in an aerosol generating system, the liquid nicotine formulation comprising: at least one water and one or more water-miscible polyhydric alcohols; and one or more partially water-soluble, water-immiscible solvents having a water solubility at 20°C of between approximately 20 mg / ml and approximately 100 mg / ml, wherein the liquid nicotine formulation has a partially water-soluble, water-immiscible solvent content greater than or equal to approximately 2 percent by weight. In accordance with a preferred embodiment of the first aspect of the invention, a cartridge for use in an aerosol generating system is also provided, the cartridge containing a liquid nicotine formulation comprising: at least one water and one or more water-miscible polyhydric alcohols; and one or more partially water-soluble, water-immiscible solvents having a water solubility at 20°C of between approximately 20 mg / ml and approximately 100 mg / ml, wherein the liquid nicotine formulation has a partially water-soluble, water-immiscible solvent content greater than or equal to approximately 2 percent by weight. According to a preferred embodiment of the first aspect of the invention, an aerosol generating system is further provided comprising: a liquid nicotine formulation comprising: at least one water and one or more water-miscible polyhydric alcohols; and one or more partially water-soluble, water-immiscible solvents having a water solubility at 20 °C of between approximately 20 mg / ml and approximately 100 mg / ml, wherein the liquid nicotine formulation has a partially water-soluble, water-immiscible solvent content greater than or equal to approximately 2 percent by weight; and an atomizer configured to generate an aerosol from the liquid nicotine formulation. According to a preferred embodiment of the second aspect of the invention, a liquid nicotine formulation is provided for use in an aerosol generating system, the liquid nicotine formulation comprising: at least one water and one or more water-miscible polyhydric alcohols; and one or more partially water-soluble, water-immiscible solvents having a partition coefficient (log P) at 20 °C of between approximately 0.05 and approximately 0.5, wherein the liquid nicotine formulation has a water-soluble, water-immiscible solvent content greater than or equal to approximately 2 percent by weight. According to a preferred embodiment of the second aspect of the invention, a cartridge for use in an aerosol generating system is also provided, the cartridge containing a liquid nicotine formulation comprising: at least one water and one or more water-miscible polyhydric alcohols; and one or more partially water-soluble, water-immiscible solvents having a partition coefficient (log P) at 20 °C of between approximately 0.05 and approximately 0.5, wherein the liquid nicotine formulation has a partially water-soluble, water-immiscible solvent content greater than or equal to approximately 2 percent by weight. According to a preferred embodiment of the second aspect of the invention, an aerosol generating system is further provided comprising: a liquid nicotine formulation comprising: at least one water and one or more water-miscible polyhydric alcohols; and one or more partially water-soluble, water-immiscible solvents having a partition coefficient (log P) at 20 °C of between approximately 0.05 and approximately 0.5, wherein the liquid nicotine formulation has a partially water-soluble, water-immiscible solvent content greater than or equal to approximately 2 percent by weight; and an atomizer configured to generate an aerosol from the liquid nicotine formulation. In embodiments where the liquid nicotine formulation comprises one or more water-miscible polyhydric alcohols, preferably the liquid nicotine formulation has a water-miscible polyhydric alcohol content of approximately 5 percent by weight or greater. More preferably, the liquid nicotine formulation has a water-miscible polyhydric alcohol content of approximately 10 percent by weight or greater. For example, the liquid nicotine formulation may have a water-miscible polyhydric alcohol content of approximately 15 percent by weight or greater, approximately 20 percent by weight or greater, or approximately 25 percent by weight or greater. In embodiments where the liquid nicotine formulation comprises one or more water-miscible polyhydric alcohols, the liquid nicotine formulation may have a water-miscible polyhydric alcohol content less than or equal to approximately 80 percent by weight or less than or equal to approximately 75 percent by weight. In embodiments where the liquid nicotine formulation comprises one or more water-miscible polyhydric alcohols, preferably the liquid nicotine formulation has a water-miscible polyhydric alcohol content of approximately 70 percent by weight or less. More preferably, the liquid nicotine formulation has a water-miscible polyhydric alcohol content of approximately 60 percent by weight or less. For example, the liquid nicotine formulation may have a water-miscible polyhydric alcohol content of approximately 50 percent by weight or less, or approximately 40 percent by weight or less. In embodiments where the liquid nicotine formulation comprises one or more water-miscible polyhydric alcohols, preferably the liquid nicotine formulation has a water-miscible polyhydric alcohol content of between approximately 5 percent by weight and approximately 70 percent by weight. For example, the liquid nicotine formulation may have a water-miscible polyhydric alcohol content of between approximately 5 percent by weight and approximately 60 percent by weight, between approximately 5 percent by weight and approximately 50 percent by weight, or between approximately 5 percent by weight and approximately 40 percent by weight. Preferably, the liquid nicotine formulation has a water-miscible polyhydric alcohol content of between approximately 10 percent by weight and approximately 70 percent by weight. For example, the liquid nicotine formulation may have a water-miscible polyhydric alcohol content of between approximately 10 percent by weight and approximately 60 percent by weight, between approximately 10 percent by weight and approximately 50 percent by weight, or between approximately 10 percent by weight and approximately 40 percent by weight. In embodiments where the liquid nicotine formulation comprises one or more water-miscible polyhydric alcohols, the liquid nicotine formulation may have a water-miscible polyhydric alcohol content of between approximately 15 percent by weight and approximately 70 percent by weight, between approximately 15 percent by weight and approximately 60 percent by weight, between approximately 15 percent by weight and approximately 50 percent by weight, or between approximately 15 percent by weight and approximately 40 percent by weight. The liquid nicotine formulation may have a water-miscible polyhydric alcohol content of between approximately 20 percent by weight and approximately 70 percent by weight, between approximately 20 percent by weight and approximately 60 percent by weight, between approximately 20 percent by weight and approximately 50 percent by weight, or between approximately 20 percent by weight and approximately 40 percent by weight. The liquid nicotine formulation may have a water miscible polyhydric alcohol content of between approximately 25 percent by weight and approximately 70 percent by weight, between approximately 25 percent by weight and approximately 60 percent by weight, between approximately 25 percent by weight and approximately 50 percent by weight, or between approximately 25 percent by weight and approximately 40 percent by weight. In embodiments in which the liquid nicotine formulation comprises one or more water-miscible polyhydric alcohols, preferably the one or more water-miscible polyhydric alcohols are selected from the group consisting of 1,3-butanediol, glycerin, propylene glycol, and triethylene glycol. Most preferably, the one or more water-miscible polyhydric alcohols are selected from the group consisting of glycerin and propylene glycol. With the highest preference, one or more water-miscible polyhydric alcohols are selected from the group consisting of vegetable glycerin and propylene glycol. According to a preferred embodiment of the first aspect of the invention, a liquid nicotine formulation is provided for use in an aerosol generating system, the liquid nicotine formulation comprising: at least one water and one or more water-miscible polyhydric alcohols selected from the group consisting of glycerin and propylene glycol; and one or more partially water-soluble, water-immiscible solvents having a water solubility at 20°C of between approximately 20 mg / ml and approximately 100 mg / ml, wherein the liquid nicotine formulation has a partially water-soluble, water-immiscible solvent content greater than or equal to approximately 2 percent by weight. According to a preferred embodiment of the first aspect of the invention, a cartridge for use in an aerosol generating system is also provided, the cartridge containing a liquid nicotine formulation comprising: at least one water and one or more water-miscible polyhydric alcohols selected from the group consisting of glycerin and propylene glycol; and one or more partially water-soluble, water-immiscible solvents having a water solubility at 20°C of between approximately 20 mg / ml and approximately 100 mg / ml. C7Q?nn / l 7Π7 / Β / Y where the liquid nicotine formulation has a water-in-water partially soluble solvent content greater than or equal to approximately 2 percent by weight. According to a preferred embodiment of the first aspect of the invention, an aerosol generating system is further provided comprising: a liquid nicotine formulation comprising: at least one water and one or more water-miscible polyhydric alcohols selected from the group consisting of glycerin and propylene glycol; and one or more partially water-soluble, water-immiscible solvents having a water solubility at 20°C of between approximately 20 mg / ml and approximately 100 mg / ml, wherein the liquid nicotine formulation has a partially water-soluble, water-immiscible solvent content greater than or equal to approximately 2 percent by weight; and an atomizer configured to generate an aerosol from the liquid nicotine formulation. According to a preferred embodiment of the second aspect of the invention, a liquid nicotine formulation is provided for use in an aerosol generating system, the liquid nicotine formulation comprising: at least one water and one or more water-miscible polyhydric alcohols selected from the group consisting of glycerin and propylene glycol; and one or more partially water-soluble, water-immiscible solvents having a partition coefficient (log P) at 20 °C of between approximately 0.05 and approximately 0.5, wherein the liquid nicotine formulation has a partially water-soluble, water-immiscible solvent content greater than or equal to approximately 2 percent by weight. According to a preferred embodiment of the second aspect of the invention, a cartridge for use in an aerosol generating system is also provided, the cartridge containing a liquid nicotine formulation comprising: at least one water and one or more water-miscible polyhydric alcohols selected from the group consisting of glycerin and propylene glycol; and one or more partially water-soluble, water-immiscible solvents having a partition coefficient (log P) at 20 °C of between approximately 0.05 and approximately 0.5. C7Q7nn / l 7Π7 / Β / Y where the liquid nicotine formulation has a water-in-water partially soluble solvent content greater than or equal to approximately 2 percent by weight. According to a preferred embodiment of the second aspect of the invention, an aerosol generating system is further provided comprising: a liquid nicotine formulation comprising: at least one water and one or more water-miscible polyhydric alcohols selected from the group consisting of glycerin and propylene glycol; and one or more partially water-soluble, water-immiscible solvents having a partition coefficient (log P) at 20 °C of between approximately 0.05 and approximately 0.5, wherein the liquid nicotine formulation has a partially water-soluble, water-immiscible solvent content greater than or equal to approximately 2 percent by weight; and an atomizer configured to generate an aerosol from the liquid nicotine formulation. In embodiments where the liquid nicotine formulation comprises one or more water-miscible polyhydric alcohols selected from the group consisting of glycerin and propylene glycol, the liquid nicotine formulation may have a combined glycerin and propylene glycol content less than or equal to approximately 80 percent by weight or less than or equal to approximately 75 percent by weight. In embodiments where the liquid nicotine formulation comprises one or more water-miscible polyhydric alcohols selected from the group consisting of glycerin and propylene glycol, preferably, the liquid nicotine formulation has a combined glycerin and propylene glycol content of approximately 70 percent by weight or less. More preferably, the liquid nicotine formulation has a combined glycerin and propylene glycol content of approximately 60 percent by weight or less. For example, the liquid nicotine formulation may have a combined glycerin and propylene glycol content of approximately 50 percent by weight or approximately 40 percent by weight or less. czajnn / i ζηζ / Ε / γ In embodiments in which the liquid nicotine formulation comprises one or more water-miscible polyhydric alcohols selected from the group consisting of glycerin and propylene glycol, the liquid nicotine formulation may have a combined glycerin and propylene glycol content of between approximately 5 percent by weight and approximately 80 percent by weight or between approximately 5 percent by weight and approximately 75 percent by weight. In embodiments where the liquid nicotine formulation comprises one or more water-miscible polyhydric alcohols selected from the group consisting of glycerin and propylene glycol, preferably, the liquid nicotine formulation has a combined glycerin and propylene glycol content of between approximately 5 percent by weight and approximately 70 percent by weight. For example, the liquid nicotine formulation may have a combined glycerin and propylene glycol content of between approximately 5 percent by weight and approximately 60 percent by weight, between approximately 5 percent by weight and approximately 50 percent by weight, or between approximately 5 percent by weight and approximately 40 percent by weight. In embodiments in which the liquid nicotine formulation comprises one or more water-miscible polyhydric alcohols selected from the group consisting of glycerin and propylene glycol, the liquid nicotine formulation may have a combined glycerin and propylene glycol content of between approximately 10 percent by weight and approximately 80 percent by weight or between approximately 10 percent by weight and approximately 75 percent by weight. Preferably, the liquid nicotine formulation has a combined glycerin and propylene glycol content of between approximately 10 percent and approximately 70 percent by weight. For example, the liquid nicotine formulation may have a combined glycerin and propylene glycol content of between approximately 10 percent and approximately 60 percent by weight, between approximately 10 percent and approximately 50 percent by weight, or between approximately 10 percent and approximately 40 percent by weight. czaynn / i ζηζ / E / γ In embodiments in which the liquid nicotine formulation comprises one or more water-miscible polyhydric alcohols selected from the group consisting of glycerin and propylene glycol, the liquid nicotine formulation may have a combined glycerin and propylene glycol content of between approximately 15 percent by weight and approximately 80 percent by weight, between approximately 15 percent by weight and approximately 75 percent by weight, between approximately 15 percent by weight and approximately 70 percent by weight, between approximately 15 percent by weight and approximately 60 percent by weight, between approximately 15 percent by weight and approximately 50 percent by weight, or between approximately 15 percent by weight and approximately 40 percent by weight. The liquid nicotine formulation may have a combined content of glycerin and propylene glycol of between approximately 20 percent by weight and approximately 80 percent by weight, between approximately 20 percent by weight and approximately 75 percent by weight, between approximately 20 percent by weight and approximately 70 percent by weight, between approximately 20 percent by weight and approximately 60 percent by weight, between approximately 20 percent by weight and approximately 50 percent by weight, or between approximately 20 percent by weight and approximately 40 percent by weight. The liquid nicotine formulation may have a combined glycerin and propylene glycol content of between approximately 25 percent by weight and approximately 80 percent by weight, between approximately 15 percent by weight and approximately 75 percent by weight, between approximately 25 percent by weight and approximately 70 percent by weight, between approximately 25 percent by weight and approximately 60 percent by weight, between approximately 25 percent by weight and approximately 50 percent by weight, or between approximately 25 percent by weight and approximately 40 percent by weight. Preferably, the liquid nicotine formulation comprises water and one or more water-miscible solvents. According to a preferred embodiment of the first aspect of the invention, a liquid nicotine formulation is provided for use in an aerosol generating system, the liquid nicotine formulation comprising: water; one or more water-miscible solvents; and one or more partially water-soluble, water-immiscible solvents having a water solubility at 20°C of between approximately 20 mg / ml and approximately 100 mg / ml, wherein the liquid nicotine formulation has a water-soluble, water-immiscible solvent content greater than or equal to approximately 2 percent by weight. In accordance with a preferred embodiment of the first aspect of the invention, a cartridge for use in an aerosol generating system is also provided, the cartridge containing a liquid nicotine formulation comprising: water; one or more water-miscible solvents; and one or more partially water-soluble, water-immiscible solvents having a water solubility at 20°C of between approximately 20 mg / ml and approximately 100 mg / ml, wherein the liquid nicotine formulation has a water-soluble, water-immiscible solvent content greater than or equal to approximately 2 percent by weight. According to a preferred embodiment of the first aspect of the invention, an aerosol generating system is further provided comprising: a liquid nicotine formulation comprising: water; one or more water-miscible solvents; and one or more partially water-soluble, water-immiscible solvents having a water solubility at 20°C of between approximately 20 mg / ml and approximately 100 mg / ml, wherein the liquid nicotine formulation has a partially water-soluble, water-immiscible solvent content greater than or equal to approximately 2 percent by weight; and an atomizer configured to generate an aerosol from the liquid nicotine formulation. According to a preferred embodiment of the second aspect of the invention, a liquid nicotine formulation is provided for use in an aerosol generating system, the liquid nicotine formulation comprising: water; one or more water-miscible solvents; and one or more partially water-soluble, water-immiscible solvents having a partition coefficient (log P) at 20 °C of between approximately 0.05 and approximately 0.5, wherein the liquid nicotine formulation has a water-soluble, water-immiscible solvent content greater than or equal to approximately 2 percent by weight. According to a preferred embodiment of the second aspect of the invention, a cartridge for use in an aerosol generating system is also provided, the cartridge containing a liquid nicotine formulation comprising: water; one or more water-miscible solvents; and one or more partially water-soluble, water-immiscible solvents having a partition coefficient (log P) at 20 °C of between approximately 0.05 and approximately 0.5, wherein the liquid nicotine formulation has a water-soluble, water-immiscible solvent content greater than or equal to approximately 2 percent by weight. According to a preferred embodiment of the second aspect of the invention, an aerosol generating system is further provided comprising: a liquid nicotine formulation comprising: water; one or more water-miscible solvents; and one or more partially water-soluble, water-immiscible solvents having a partition coefficient (log P) at 20 °C of between approximately 0.05 and approximately 0.5, wherein the liquid nicotine formulation has a partially water-soluble, water-immiscible solvent content greater than or equal to approximately 2 percent by weight; and an atomizer configured to generate an aerosol from the liquid nicotine formulation. The liquid nicotine formulation may have a combined water and water-miscible solvent content greater than or equal to approximately 50 percent by weight, or greater than or equal to approximately 55 percent by weight. Preferably, the liquid nicotine formulation has a combined water and water-miscible solvent content greater than or equal to approximately 60 percent by weight. More preferably, the liquid nicotine formulation has a combined water and water-miscible solvent content greater than or equal to 65 percent by weight. For example, the liquid nicotine formulation may have a combined water and water-miscible solvent content greater than or equal to approximately 70 percent by weight, greater than or equal to approximately 75 percent by weight, greater than or equal to approximately 80 percent by weight, or greater than or equal to approximately 85 percent by weight. Preferably, the liquid nicotine formulation comprises water and one or more water-miscible polyhydric alcohols. According to a more preferred embodiment of the first aspect of the invention, a liquid nicotine formulation is provided for use in an aerosol generating system, the liquid nicotine formulation comprising: water; one or more water-miscible polyhydric alcohols; and one or more partially water-soluble, water-immiscible solvents having a water solubility at 20°C of between approximately 20 mg / ml and approximately 100 mg / ml, wherein the liquid nicotine formulation has a partially water-soluble, water-immiscible solvent content greater than or equal to approximately 2 percent by weight. In accordance with a more preferred embodiment of the first aspect of the invention, a cartridge is also provided for use in an aerosol generating system, the cartridge containing a liquid nicotine formulation comprising: water; one or more water-miscible polyhydric alcohols; and one or more partially water-soluble, water-immiscible solvents having a water solubility at 20°C of between approximately 20 mg / ml and approximately 100 mg / ml, wherein the liquid nicotine formulation has a partially water-soluble, water-immiscible solvent content greater than or equal to approximately 2 percent by weight. According to a more preferred embodiment of the first aspect of the invention, an aerosol generating system is further provided comprising: a liquid nicotine formulation comprising: water; one or more water-miscible polyhydric alcohols; and one or more partially water-soluble, water-immiscible solvents having a water solubility at 20°C of between approximately 20 mg / ml and approximately 100 mg / ml, wherein the liquid nicotine formulation has a water-soluble, partially water-immiscible solvent content greater than or equal to approximately 2 percent by weight; and an atomizer configured to generate an aerosol from the liquid nicotine formulation. According to a more preferred embodiment of the second aspect of the invention, a liquid nicotine formulation is provided for use in an aerosol generating system, the liquid nicotine formulation comprising: water; one or more water-miscible polyhydric alcohols; and one or more partially water-soluble, water-immiscible solvents having a partition coefficient (log P) at 20 °C of between approximately 0.05 and approximately 0.5, wherein the liquid nicotine formulation has a water-soluble, water-immiscible solvent content greater than or equal to approximately 2 percent by weight. In accordance with a more preferred embodiment of the second aspect of the invention, a cartridge is also provided for use in an aerosol generating system, the cartridge containing a liquid nicotine formulation comprising: water; one or more water-miscible polyhydric alcohols; and one or more partially water-soluble, water-immiscible solvents having a partition coefficient (log P) at 20 °C of between approximately 0.05 and approximately 0.5, wherein the liquid nicotine formulation has a partially water-soluble, water-immiscible solvent content greater than or equal to approximately 2 percent by weight. According to a more preferred embodiment of the second aspect of the invention, an aerosol generating system is further provided comprising: a liquid nicotine formulation comprising: water; one or more water-miscible polyhydric alcohols; and one or more partially water-soluble, water-immiscible solvents having a partition coefficient (log P) at 20 °C of between approximately 0.05 and approximately 0.5, wherein the liquid nicotine formulation has a partially water-soluble, water-immiscible solvent content greater than or equal to approximately 2 percent by weight; and an atomizer configured to generate an aerosol from the liquid nicotine formulation. czajnn / i ζηζ / Ε / γ In embodiments where the liquid nicotine formulation comprises water and one or more water-miscible polyhydric alcohols, the liquid nicotine formulation may have a combined water and water-miscible polyhydric alcohol content greater than or equal to approximately 50 percent by weight or greater than or equal to approximately 55 percent by weight. In embodiments where the liquid nicotine formulation comprises water and one or more water-miscible polyhydric alcohols, preferably, the liquid nicotine formulation has a combined water and water-miscible polyhydric alcohol content of approximately 60 percent by weight or greater. More preferably, the liquid nicotine formulation has a combined water and water-miscible polyhydric alcohol content of 65 percent by weight or greater. For example, the liquid nicotine formulation may have a combined water and water-miscible polyhydric alcohol content of approximately 70 percent by weight or greater, approximately 75 percent by weight or greater, approximately 80 percent by weight or greater, or approximately 85 percent by weight or greater. With the highest preference, the liquid nicotine formulation comprises water and one or more water-miscible polyhydric alcohols selected from the group consisting of glycerin and propylene glycol. According to a more preferred embodiment of the first aspect of the invention, a liquid nicotine formulation is provided for use in an aerosol generating system, the liquid nicotine formulation comprising: water; one or more water-miscible polyhydric alcohols selected from the group consisting of glycerin and propylene glycol; and one or more partially water-soluble, water-immiscible solvents having a water solubility at 20°C of between approximately 20 mg / ml and approximately 100 mg / ml, wherein the liquid nicotine formulation has a partially water-soluble, water-immiscible solvent content greater than or equal to approximately 2 percent by weight. czaynn / i ζηζ / E / γ In accordance with a more preferred embodiment of the first aspect of the invention, a cartridge for use in an aerosol generating system is also provided, the cartridge containing a liquid nicotine formulation comprising: water; one or more water-miscible polyhydric alcohols selected from the group consisting of glycerin and propylene glycol; and one or more partially water-soluble, water-immiscible solvents having a water solubility at 20°C of between approximately 20 mg / ml and approximately 100 mg / ml, wherein the liquid nicotine formulation has a partially water-soluble, water-immiscible solvent content greater than or equal to approximately 2 percent by weight. According to a more preferred embodiment of the first aspect of the invention, an aerosol generating system is further provided comprising: a liquid nicotine formulation comprising: water; one or more water-miscible polyhydric alcohols selected from the group consisting of glycerin and propylene glycol; and one or more partially water-soluble, water-immiscible solvents having a water solubility at 20°C of between approximately 20 mg / ml and approximately 100 mg / ml, wherein the liquid nicotine formulation has a partially water-soluble, water-immiscible solvent content greater than or equal to approximately 2 percent by weight; and an atomizer configured to generate an aerosol from the liquid nicotine formulation. According to a more preferred embodiment of the second aspect of the invention, an aerosol generating system is further provided comprising: a liquid nicotine formulation comprising: water; one or more water-miscible polyhydric alcohols selected from the group consisting of glycerin and propylene glycol; and one or more partially water-soluble, water-immiscible solvents having a partition coefficient (log P) at 20 °C of between approximately 0.05 and approximately 0.5, wherein the liquid nicotine formulation has a partially water-soluble, water-immiscible solvent content greater than or equal to approximately 2 percent by weight. czaynn / i ζηζ / E / γ In accordance with a more preferred embodiment of the second aspect of the invention, a cartridge for use in an aerosol generating system is also provided, the cartridge containing a liquid nicotine formulation comprising: water; one or more water-miscible polyhydric alcohols selected from the group consisting of glycerin and propylene glycol; and one or more partially water-soluble, water-immiscible solvents having a partition coefficient (log P) at 20 °C of between approximately 0.05 and approximately 0.5, wherein the liquid nicotine formulation has a partially water-soluble, water-immiscible solvent content greater than or equal to approximately 2 percent by weight. According to a more preferred embodiment of the second aspect of the invention, an aerosol generating system is further provided comprising: a liquid nicotine formulation comprising: water; one or more water-miscible polyhydric alcohols selected from the group consisting of glycerin and propylene glycol; and one or more partially water-soluble, water-immiscible solvents having a partition coefficient (log P) at 20 °C of between approximately 0.05 and approximately 0.5, wherein the liquid nicotine formulation has a partially water-soluble, water-immiscible solvent content greater than or equal to approximately 2 percent by weight; and an atomizer configured to generate an aerosol from the liquid nicotine formulation. In embodiments where the liquid nicotine formulation comprises water and one or more water-miscible polyhydric alcohols selected from the group consisting of glycerin and propylene glycol, the liquid nicotine formulation may have a combined content of water, glycerin, and propylene glycol greater than or equal to approximately 50 percent by weight or greater than or equal to approximately 55 percent by weight. In embodiments where the liquid nicotine formulation comprises water and one or more water-miscible polyhydric alcohols selected from the group consisting of glycerin and propylene glycol, preferably, the liquid nicotine formulation has a combined content of water, glycerin, and propylene glycol greater than or equal to approximately 60 percent by weight. C7Q?nn / l 7P7 / E / Y greater preference, the liquid nicotine formulation has a combined content of water, glycerin, and propylene glycol greater than or equal to 65 percent by weight. For example, the liquid nicotine formulation may have a combined content of water, glycerin, and propylene glycol greater than or equal to approximately 70 percent by weight, greater than or equal to approximately 75 percent by weight, greater than or equal to approximately 80 percent by weight, or greater than or equal to approximately 85 percent by weight. Preferably, the liquid nicotine formulation has a glycerin content greater than or equal to approximately 5 percent by weight. Ideally, the liquid nicotine formulation has a glycerin content of approximately 6 percent by weight or greater. For example, the liquid nicotine formulation may have a glycerin content of approximately 7 percent by weight or greater, or approximately 8 percent by weight or greater. The liquid nicotine formulation may have a glycerin content less than or equal to approximately 80 percent by weight or less than or equal to approximately 75 percent by weight. Preferably, the liquid nicotine formulation has a glycerin content of approximately 70 percent by weight or less. More preferably, the liquid nicotine formulation has a glycerin content of approximately 60 percent by weight or less. For example, the liquid nicotine formulation may have a glycerin content of approximately 50 percent by weight or approximately 40 percent by weight or less. Preferably, the liquid nicotine formulation has a glycerin content of between approximately 5 percent by weight and approximately 70 percent by weight. For example, the liquid nicotine formulation may have a glycerin content of between approximately 5 percent by weight and approximately 60 percent by weight, between approximately 5 percent by weight and approximately 50 percent by weight, or between approximately 5 percent by weight and approximately 40 percent by weight. Preferably, the liquid nicotine formulation has a glycerin content of between approximately 6 percent by weight and approximately 70 percent by weight. For example, the liquid nicotine formulation may have a glycerin content of between approximately 6 percent by weight and approximately 60 percent by weight, between approximately 6 percent by weight and approximately 50 percent by weight, or between approximately 6 percent by weight and approximately 40 percent by weight. The liquid nicotine formulation may have a glycerin content of between approximately 7 percent by weight and approximately 70 percent by weight, between approximately 7 percent by weight and approximately 60 percent by weight, between approximately 7 percent by weight and approximately 50 percent by weight, or between approximately 7 percent by weight and approximately 40 percent by weight. Liquid nicotine formulations may have a glycerin content of between approximately 8 percent by weight and approximately 70 percent by weight, between approximately 8 percent by weight and approximately 60 percent by weight, between approximately 8 percent by weight and approximately 50 percent by weight, or between approximately 8 percent by weight and approximately 40 percent by weight. The liquid nicotine formulation comprises one or more water-immiscible solvents. As used herein with reference to the first aspect of the invention, the term “water-immiscible solvent” describes a compound that is liquid at 20 °C and has a solubility in water at 20 °C less than or equal to approximately 100 mg / ml. As used herein with reference to the second aspect of the invention, the term “water-immiscible solvent” describes a compound that is liquid at 20 °C and has a partition coefficient (log P) at 20 °C greater than or equal to approximately 0.05. c^aynn / i ζηζ / E / γ According to the first aspect of the invention, the liquid nicotine formulation comprises one or more partially water-soluble, water-immiscible solvents having a water solubility at 20°C of between approximately 20 mg / ml and approximately 100 mg / ml. In accordance with the second aspect of the invention, the liquid nicotine formulation comprises one or more partially water-soluble, water-immiscible solvents having a partition coefficient (log P) at 20 °C of between approximately 0.05 and approximately 0.5. One or more partially water-soluble, water-immiscible solvents can advantageously help to dissolve and stabilize the non-polar components of the liquid nicotine formulation. One or more partially water-soluble, water-immiscible solvents can reduce the hygroscopicity of an aerosol generated from a liquid nicotine formulation when used in an aerosol generating system. This can advantageously reduce or prevent increases in aerosol particle or droplet size when inhaled by a user as a result of water adsorption in the respiratory tract. The liquid nicotine formulation has a partially water-soluble solvent content, immiscible in water, greater than or equal to approximately 2 percent by weight. Preferably, the liquid nicotine formulation has a water-in-water, partially soluble solvent content greater than or equal to approximately 2.5 percent by weight. For example, the liquid nicotine formulation may have a water-in-water, partially soluble solvent content greater than or equal to approximately 3 percent by weight, greater than or equal to approximately 4 percent by weight, greater than or equal to approximately 5 percent by weight, greater than or equal to approximately 6 percent by weight, greater than or equal to approximately 7 percent by weight, or greater than or equal to approximately 8 percent by weight. czaynn / i ζηζ / E / γ Preferably, the liquid nicotine formulation has a water-insoluble, partially soluble solvent content of approximately 30 percent by weight or less. For example, the liquid nicotine formulation may have a water-insoluble, partially soluble solvent content of approximately 25 percent by weight or less, approximately 20 percent by weight or less, or approximately 15 percent by weight or less. Preferably, the liquid nicotine formulation has a water-in-water, partially soluble solvent content of between approximately 2 percent by weight and approximately 30 percent by weight. For example, the liquid nicotine formulation may have a water-in-water, partially soluble solvent content of between approximately 2 percent by weight and approximately 25 percent by weight, between approximately 2 percent by weight and approximately 20 percent by weight, or between approximately 2 percent by weight and approximately 15 percent by weight. Preferably, the liquid nicotine formulation has a water-in-water, partially soluble solvent content of between approximately 2.5 percent and approximately 30 percent by weight. For example, the liquid nicotine formulation may have a water-in-water, partially soluble solvent content of between approximately 2.5 percent and approximately 25 percent by weight, between approximately 2.5 percent and approximately 20 percent by weight, or between approximately 2.5 percent and approximately 15 percent by weight. The liquid nicotine formulation may have a water-in-water, partially soluble solvent content of between approximately 3 percent and approximately 30 percent by weight. For example, the liquid nicotine formulation may have a water-in-water, partially soluble solvent content of between approximately 3 percent and approximately 25 percent by weight, between approximately 3 percent and approximately 20 percent by weight, or between approximately 3 percent and approximately 15 percent by weight. Liquid nicotine formulations may have a water-in-water, partially soluble solvent content of between approximately 4 percent by weight and approximately 30 percent by weight. For example, liquid nicotine formulations may have a water-in-water, partially soluble solvent content of between approximately 4 percent by weight and approximately 25 percent by weight, between approximately 4 percent by weight and approximately 20 percent by weight, or between approximately 4 percent by weight and approximately 15 percent by weight. Liquid nicotine formulations may have a water-in-water, partially soluble solvent content of between approximately 5 percent and approximately 30 percent by weight. For example, liquid nicotine formulations may have a water-in-water, partially soluble solvent content of between approximately 5 percent and approximately 25 percent by weight, between approximately 5 percent and approximately 20 percent by weight, or between approximately 5 percent and approximately 15 percent by weight. Liquid nicotine formulations may have a water-in-water, partially soluble solvent content of between approximately 6 percent and approximately 30 percent by weight. For example, liquid nicotine formulations may have a water-in-water, partially soluble solvent content of between approximately 6 percent and approximately 25 percent by weight, between approximately 6 percent and approximately 20 percent by weight, or between approximately 6 percent and approximately 15 percent by weight. Liquid nicotine formulations may contain a partially water-soluble, water-immiscible solvent of between approximately 7 percent and approximately 30 percent by weight. For example, a liquid nicotine formulation may contain C7Q7nn / l 7Π7 / Β / Y solvent partially soluble in water, immiscible in water from approximately 7 percent by weight to approximately 25 percent by weight, from approximately 7 percent by weight to approximately 20 percent by weight or from approximately 7 percent by weight to approximately 15 percent by weight. Liquid nicotine formulations may have a water-in-water, partially soluble solvent content of between approximately 8 percent and approximately 30 percent by weight. For example, liquid nicotine formulations may have a water-in-water, partially soluble solvent content of between approximately 8 percent and approximately 25 percent by weight, between approximately 8 percent and approximately 20 percent by weight, or between approximately 8 percent and approximately 15 percent by weight. The ratio of the weight percent of water-soluble, water-immiscible solvent content to the weight percent of nicotine content of the liquid nicotine formulation may be greater than or equal to approximately 0.75. That is, the weight percent of the water-in-water partially soluble solvent content of the liquid nicotine formulation can be at least approximately 0.75 times the weight percent of the nicotine content of the liquid nicotine formulation. Preferably, the ratio of the weight percent of water-in-partially soluble, water-immiscible solvent content to the weight percent of nicotine content in the liquid nicotine formulation is greater than or equal to approximately 1. For example, the ratio of the weight percent of water-in-partially soluble, water-immiscible solvent content to the weight percent of nicotine content in the liquid nicotine formulation may be greater than or equal to approximately 1.25, greater than or equal to approximately 1.5, or greater than or equal to approximately 1.75. C7Q7nn / l 7Π7 / Β / Y The ratio of the weight percent of water-soluble, water-immiscible solvent content to the weight percent of nicotine content of the liquid nicotine formulation may be less than or equal to approximately 20. In other words, the weight percent of water-soluble, water-immiscible solvent content of the liquid nicotine formulation may be less than or equal to 20 times the weight percent of nicotine content of the liquid nicotine formulation. Preferably, the ratio of the weight percent of water-in-partially soluble, water-immiscible solvent content to the weight percent of nicotine content in the liquid nicotine formulation is less than or equal to approximately 18. For example, the ratio of the weight percent of water-in-partially soluble, water-immiscible solvent content to the weight percent of nicotine content in the liquid nicotine formulation may be less than or equal to approximately 16, less than or equal to approximately 14, or greater than or equal to approximately 12. The weight percent ratio of water-in-water partially soluble solvent content, immiscible in water, to the weight percent nicotine content of the liquid nicotine formulation may be between approximately 0.75 and approximately 20, between approximately 0.75 and approximately 18, between approximately 0.75 and approximately 16, between approximately 0.75 and approximately 14, or between approximately 0.75 and approximately 12. Preferably, the ratio of the weight percent of water-soluble, water-immiscible solvent content to the weight percent of nicotine content of the liquid nicotine formulation is between approximately 1 and approximately 20, between approximately 1 and approximately 18, between approximately 1 and approximately 16, between approximately 1 and approximately 14, or between approximately 1 and approximately 12. C7Q?nn / l 7Π7 / Β / Y The weight percent ratio of water-partially soluble, water-immiscible solvent content to weight percent of nicotine content in the liquid nicotine formulation may be between approximately 1.25 and approximately 20, between approximately 1.25 and approximately 18, between approximately 1.25 and approximately 16, between approximately 1.25 and approximately 14, or between approximately 1.25 and approximately 12. The weight percent ratio of water-partially soluble, water-immiscible solvent content to weight percent of nicotine content in the liquid nicotine formulation may be between approximately 1.5 and approximately 20, between approximately 1.5 and approximately 18, between approximately 1.5 and approximately 16, between approximately 1.5 and approximately 14, or between approximately 1.5 and approximately 12. The weight percent ratio of water-in-partially soluble, water-immiscible solvent content to weight percent of nicotine content in the liquid nicotine formulation may be between approximately 1.75 and approximately 20, between approximately 1.75 and approximately 18, between approximately 1.75 and approximately 16, between approximately 1.75 and approximately 14, or between approximately 1.75 and approximately 12. The ratio of the weight percent of water-soluble, water-immiscible solvent content to the weight percent of water-miscible solvent content of the liquid nicotine formulation may be greater than or equal to approximately 0.06. That is, the weight percent of water-soluble, water-immiscible solvent content of the liquid nicotine formulation can be at least approximately 0.06 times the weight percent of water-miscible solvent content of the liquid nicotine formulation. czajnn / i ζηζ / Ε / γ Preferably, the ratio of the weight percent of water-partially soluble, water-immiscible solvent content to the weight percent of water-miscible solvent content in the liquid nicotine formulation is greater than or equal to approximately 0.08. For example, the ratio of the weight percent of water-partially soluble, water-immiscible solvent content to the weight percent of water-miscible solvent content in the liquid nicotine formulation may be greater than or equal to approximately 0.1, greater than or equal to approximately 0.12, or greater than or equal to approximately 0.14. The ratio of the weight percent of water-partially soluble, water-immiscible solvent content to the weight percent of water-miscible solvent content of the liquid nicotine formulation may be less than or equal to approximately 1.2. That is, the weight percent of water-soluble, water-immiscible solvent content of the liquid nicotine formulation may be less than or equal to approximately 1.2 times the weight percent of water-miscible solvent content of the liquid nicotine formulation. Preferably, the ratio of the weight percent of water-partially soluble, water-immiscible solvent content to the weight percent of water-miscible solvent content in the liquid nicotine formulation is less than or equal to approximately 1. For example, the ratio of the weight percent of water-partially soluble, water-immiscible solvent content to the weight percent of water-miscible solvent content in the liquid nicotine formulation may be less than or equal to approximately 0.8, less than or equal to approximately 0.6, or less than or equal to approximately 0.4. The weight percent ratio of water-partially soluble, water-immiscible solvent content to the weight percent of water-miscible solvent content of the liquid nicotine formulation may be between approximately 0.06 and approximately 1.2, between approximately 0.06 and approximately 1, between approximately 0.06 and approximately 0.8, between approximately 0.06 and approximately 0.6, or between approximately 0.06 and approximately 0.4. Preferably, the weight percent ratio of water-partially soluble, water-immiscible solvent content to weight percent of water-miscible solvent content of the liquid nicotine formulation is between approximately 0.08 and approximately 1.2, between approximately 0.08 and approximately 1, between approximately 0.08 and approximately 0.8, between approximately 0.08 and approximately 0.6, or between approximately 0.08 and approximately 0.4. The weight percent ratio of water-partially soluble, water-immiscible solvent content to the weight percent of water-miscible solvent content of the liquid nicotine formulation may be between approximately 0.1 and approximately 1.2, between approximately 0.1 and approximately 1, between approximately 0.1 and approximately 0.8, between approximately 0.1 and approximately 0.6, or between approximately 0.1 and approximately 0.4. The weight percent ratio of water-partially soluble, water-immiscible solvent content to the weight percent of water-miscible solvent content of the liquid nicotine formulation may be between approximately 0.12 and approximately 1.2, between approximately 0.12 and approximately 1, between approximately 0.12 and approximately 0.8, between approximately 0.1 and approximately 0.6, or between approximately 0.12 and approximately 0.4. The weight percent ratio of water-partially soluble, water-immiscible solvent content to the weight percent of water-miscible solvent content of the liquid nicotine formulation may be between approximately 0.14 and approximately 1.2, between approximately 0.14 and approximately 1, between approximately 0.14 and approximately 0.8, between approximately 0.14 and approximately 0.6, or between approximately 0.14 and approximately 0.4. czaynn / i ζηζ / E / γ The ratio of the weight percent of water-soluble, water-immiscible solvent content to the weight percent of water content of the liquid nicotine formulation may be greater than or equal to approximately 0.025. That is, the weight percent of water-soluble, water-immiscible solvent content of the liquid nicotine formulation can be at least approximately 0.02 times the weight percent of water content of the liquid nicotine formulation. Preferably, the ratio of the weight percent of water-partially soluble, water-immiscible solvent content to the weight percent of water content in the liquid nicotine formulation is greater than or equal to approximately 0.03. For example, the ratio of the weight percent of water-partially soluble, water-immiscible solvent content to the weight percent of water content in the liquid nicotine formulation may be greater than or equal to approximately 0.05, greater than or equal to approximately 0.075, or greater than or equal to approximately 0.1. The ratio of the weight percent of water-partially soluble solvent content, immiscible in water, to the weight percent of water content of the liquid nicotine formulation may be less than or equal to approximately 5. That is, the weight percent of water-soluble, water-immiscible solvent content of the liquid nicotine formulation may be less than or equal to approximately 5 times the weight percent of water content of the liquid nicotine formulation. Preferably, the ratio of the weight percent of water-partially soluble, water-immiscible solvent content to the weight percent of water content in the liquid nicotine formulation is less than or equal to approximately 1. For example, the ratio of the weight percent of water-partially soluble, water-immiscible solvent content to the weight percent of water content in the liquid nicotine formulation may be less than or equal to approximately 0.8, less than or equal to approximately 0.6, or less than or equal to approximately 0.4. czajnn / i ζηζ / Ε / γ The ratio of the weight percent of water-soluble, water-immiscible solvent content to the weight percent of water content of the liquid nicotine formulation may be between approximately 0.02 and approximately 1.2, between approximately 0.02 and approximately 1, between approximately 0.02 and approximately 0.8, between approximately 0.02 and approximately 0.6, or between approximately 0.02 and approximately 0.4. Preferably, the weight percent ratio of water-partially soluble, water-immiscible solvent content to weight percent of water content in the liquid nicotine formulation is between approximately 0.03 and approximately 1.2, between approximately 0.03 and approximately 1, between approximately 0.03 and approximately 0.8, between approximately 0.03 and approximately 0.6, or between approximately 0.03 and approximately 0.4. The ratio of the weight percent of water-soluble, water-immiscible solvent content to the weight percent of water content of the liquid nicotine formulation may be between approximately 0.05 and approximately 1.2, between approximately 0.05 and approximately 1, between approximately 0.05 and approximately 0.8, between approximately 0.05 and approximately 0.6, or between approximately 0.05 and approximately 0.4. The ratio of the weight percent of water-soluble, water-immiscible solvent content to the weight percent of water content of the liquid nicotine formulation may be between approximately 0.75 and approximately 1.2, between approximately 0.75 and approximately 1, between approximately 0.75 and approximately 0.8, between approximately 0.75 and approximately 0.6, or between approximately 0.75 and approximately 0.4. The weight percent ratio of water-partially soluble solvent content, immiscible in water, to the weight percent water content of the liquid nicotine formulation czajnn / i ζηζ / E / γ may be between approximately 0.1 and approximately 1.2, between approximately 0.1 and approximately 1, between approximately 0.1 and approximately 0.8, between approximately 0.1 and approximately 0.6, or between approximately 0.1 and approximately 0.4. One or more partially water-soluble, water-immiscible solvents may have a maximum carbon chain length less than or equal to 12. For example, one or more partially water-soluble, water-immiscible solvents may have a maximum carbon chain length less than or equal to 10. Preferably, one or more partially water-soluble, water-immiscible solvents are selected from the group consisting of polysorbate 80, triethyl citrate, and triacetin. Preferably, one or more partially water-soluble, water-immiscible solvents are selected from the group consisting of triethyl citrate and triacetin. The liquid nicotine formulation may comprise one or more water-insoluble solvents, immiscible in water. As used herein with reference to the first aspect of the invention, the term “water-insoluble, water-immiscible solvent” describes a compound that is liquid at 20 °C and has a solubility in water at 20 °C less than or equal to approximately 5 mg / ml. As used herein with reference to the second aspect of the invention, the term “water-insoluble, water-immiscible solvent” describes a compound that is liquid at 20 °C and has a partition coefficient (log P) at 20 °C greater than approximately 5. The liquid nicotine formulation may have a water-insoluble, water-immiscible solvent content greater than or equal to approximately 0.5 percent by weight, or greater than or equal to approximately 1 percent by weight. For example, the liquid nicotine formulation may have a water-insoluble, water-immiscible solvent content greater than or equal to approximately 2 percent by weight, greater than or equal to approximately 3 percent by weight, greater than or equal to approximately 4 percent by weight, or greater than or equal to approximately 6 percent by weight. The liquid nicotine formulation may have a water-insoluble, water-immiscible solvent content of approximately 30 percent by weight or less, or approximately 25 percent by weight or less. For example, the liquid nicotine formulation may have a water-insoluble, water-immiscible solvent content of approximately 20 percent by weight or less, approximately 15 percent by weight or less, or approximately 10 percent by weight or less. Liquid nicotine formulations may have a water-insoluble, water-immiscible solvent content of between approximately 0.5 percent and approximately 30 percent by weight, or between approximately 0.5 percent and approximately 25 percent by weight. For example, liquid nicotine formulations may have a water-insoluble, water-immiscible solvent content of between approximately 0.5 percent and approximately 20 percent by weight, between approximately 0.5 percent and approximately 15 percent by weight, or between approximately 0.5 percent and approximately 10 percent by weight. Liquid nicotine formulations may have a water-insoluble, water-immiscible solvent content of between approximately 1 percent by weight and approximately 30 percent by weight, or between approximately 1 percent by weight and approximately 25 percent by weight. For example, liquid nicotine formulations may have a water-insoluble, water-immiscible solvent content of between approximately 1 percent by weight and approximately 20 percent by weight, between approximately 1 percent by weight and approximately 15 percent by weight, or between approximately 1 percent by weight and approximately 10 percent by weight. The liquid nicotine formulation may have a water-insoluble, water-immiscible solvent content of between approximately 2 percent by weight and approximately 30 percent by weight, or between approximately 2 percent by weight and approximately 25 percent by weight. For example, the liquid nicotine formulation may have a water-insoluble, water-immiscible solvent content of between approximately 2 percent by weight and approximately 20 percent by weight, between approximately 2 percent by weight and approximately 15 percent by weight, or between approximately 2 percent by weight and approximately 10 percent by weight. Liquid nicotine formulations may have a water-insoluble, water-immiscible solvent content of between approximately 3 percent by weight and approximately 30 percent by weight, or between approximately 3 percent by weight and approximately 25 percent by weight. For example, liquid nicotine formulations may have a water-insoluble, water-immiscible solvent content of between approximately 3 percent by weight and approximately 20 percent by weight, between approximately 3 percent by weight and approximately 15 percent by weight, or between approximately 3 percent by weight and approximately 10 percent by weight. Liquid nicotine formulations may have a water-insoluble, water-immiscible solvent content of between approximately 4 percent by weight and approximately 30 percent by weight, or between approximately 4 percent by weight and approximately 25 percent by weight. For example, liquid nicotine formulations may have a water-insoluble, water-immiscible solvent content of between approximately 4 percent by weight and approximately 20 percent by weight, between approximately 4 percent by weight and approximately 15 percent by weight, or between approximately 4 percent by weight and approximately 10 percent by weight. The liquid nicotine formulation may have a water-insoluble, water-immiscible solvent content of between approximately 6 percent by weight and approximately 30 percent by weight, or between approximately 6 percent by weight and approximately 25 percent by weight. For example, the liquid nicotine formulation may have a water-insoluble, water-immiscible solvent content of between approximately 6 percent by weight and approximately 20 percent by weight, between approximately 6 percent by weight and approximately 15 percent by weight, or between approximately 6 percent by weight and approximately 10 percent by weight. The one or more water-insoluble, water-immiscible solvents may have a maximum carbon chain length less than or equal to 30. For example, the one or more water-insoluble, water-immiscible solvents may have a maximum carbon chain length less than or equal to 20, less than or equal to 18, less than or equal to 16, less than or equal to 14, or less than or equal to 12. Suitable water-insoluble, water-immiscible solvents include, but are not limited to, oleic acid and MIGLYOL® (a mixture of decanoyl and octanoyl glycerides). The ratio of the weight percent of water-partially soluble, water-immiscible solvent content to the weight percent of water-insoluble, water-immiscible solvent content of the liquid nicotine formulation may be greater than or equal to approximately 0.2. That is, the weight percent of water-partially soluble, water-immiscible solvent content of the liquid nicotine formulation may be at least approximately 0.2 times the weight percent of water-insoluble, water-immiscible solvent content of the liquid nicotine formulation. Preferably, the weight percent ratio of water-partially soluble, water-immiscible solvent content to the weight percent of water-insoluble, water-immiscible solvent content in the liquid nicotine formulation is greater than or equal to approximately 0.4. For example, the weight percent ratio of water-partially soluble, water-immiscible solvent content to the weight percent of water-insoluble, water-immiscible solvent content in the liquid nicotine formulation may be greater than or equal to approximately 0.6, greater than or equal to approximately 0.8, or greater than or equal to approximately 1. czajnn / i ζηζ / Ε / γ The weight percent ratio of partially water-soluble, water-immiscible solvent content to the weight percent of water-insoluble, water-immiscible solvent content of the liquid nicotine formulation may be less than or equal to approximately 35. That is, the weight percent of water-partially soluble, water-immiscible solvent content of the liquid nicotine formulation may be less than or equal to 35 times the weight percent of water-insoluble, water-immiscible solvent content of the liquid nicotine formulation. Preferably, the weight percent ratio of water-partially soluble, water-immiscible solvent content to the weight percent of water-insoluble, water-immiscible solvent content in the liquid nicotine formulation is less than or equal to approximately 30. For example, the weight percent ratio of water-partially soluble, water-immiscible solvent content to the weight percent of water-insoluble, water-immiscible solvent content in the liquid nicotine formulation may be less than or equal to approximately 25, less than or equal to approximately 20, or less than or equal to approximately 15. The weight percent ratio of partially water-soluble, water-immiscible solvent content to weight percent of water-insoluble, water-immiscible solvent content in the liquid nicotine formulation may be between approximately 0.2 and approximately 35, between approximately 0.2 and approximately 30, between approximately 0.2 and approximately 25, between approximately 0.2 and approximately 20, or between approximately 0.2 and approximately 15. Preferably, the weight percent ratio of water-partially soluble, water-immiscible solvent content to weight percent of water-insoluble, water-immiscible solvent content of the liquid nicotine formulation is between approximately 0.4 and approximately 35, between approximately 0.4 and approximately czaynn / i ζηζ / E / γ, between approximately 0.4 and approximately 25, between approximately 0.4 and approximately 20, or between approximately 0.4 and approximately 15. The weight percent ratio of partially water-soluble, water-immiscible solvent content to weight percent of water-insoluble, water-immiscible solvent content in the liquid nicotine formulation may be between approximately 0.6 and approximately 35, between approximately 0.6 and approximately 30, between approximately 0.6 and approximately 25, between approximately 0.6 and approximately 20, or between approximately 0.6 and approximately 15. The weight percent ratio of partially water-soluble, water-immiscible solvent content to weight percent of water-insoluble, water-immiscible solvent content in the liquid nicotine formulation may be between approximately 0.8 and approximately 35, between approximately 0.8 and approximately 30, between approximately 0.8 and approximately 25, between approximately 0.8 and approximately 20, or between approximately 0.8 and approximately 15. The liquid nicotine formulation can be a liquid nicotine formulation that is substantially caffeine-free. As used herein with reference to the invention, the term “substantially caffeine-free liquid nicotine formulation” describes a liquid nicotine formulation having a caffeine content of less than 0.5 percent by weight. For example, the liquid nicotine formulation may have a caffeine content of less than approximately 0.4 percent by weight, less than approximately 0.3 percent by weight, or less than approximately 0.2 percent by weight. The liquid nicotine formulation can be a liquid nicotine formulation that is substantially caffeine-free. czaynn / i ζηζ / E / γ As used herein with reference to the invention, the term “substantially caffeine-free liquid nicotine formulation” describes a liquid nicotine formulation having a caffeine content of less than approximately 0.1 percent by weight. The liquid nicotine formulation may be a caffeine-free liquid nicotine formulation. As used herein with reference to the invention, the term “caffeine-free liquid nicotine formulation” describes a liquid nicotine formulation having a caffeine content of 0 percent by weight. As used herein with reference to the invention, the term “caffeine” describes caffeine or a caffeine salt. When referring to a caffeine salt, the amounts of caffeine quoted herein are the amounts of caffeine cation. The liquid nicotine formulation may comprise one or more solid emulsifiers. As used herein with reference to the invention, the term “solid emulsifier” describes an emulsifier that is solid at 20°C. Suitable solid emulsifiers include, but are not limited to, 1-stearoyl-rac-glycerol, Kolliphor® P 188, sodium caseinate, sodium dodecanoate, and sodium docusate. Preferably, the liquid nicotine formulation has a solid emulsifier content of approximately 8 percent by weight or less. More preferably, the liquid nicotine formulation has a solid emulsifier content of approximately 5 percent by weight or less. Preferably, the liquid nicotine formulation comprises one or more water-soluble organic acids. As used herein, with reference to the invention, the term “water-soluble organic acid” describes an organic acid having a solubility in water at 20 °C greater than or equal to approximately 500 mg / ml. One or more water-soluble organic acids can be advantageously combined with nicotine in the liquid nicotine formulation by forming one or more nicotine salts. czaynn / i ζηζ / E / γ One or more nicotine salts can be advantageously dissolved and stabilized in at least one water and one or more water-miscible solvents. This can advantageously reduce nicotine adsorption in the upper respiratory tract and enhance nicotine delivery and pulmonary retention, as discussed previously. Most preferably, the liquid nicotine formulation comprises one or more water-soluble carboxylic acids. Suitable water-soluble carboxylic acids include, but are not limited to, acetic acid, citric acid, lactic acid, levulinic acid, malic acid, malonic acid, and pyruvic acid. With the highest preference, the liquid nicotine formulation comprises lactic acid. Preferably, the liquid nicotine formulation has a water-soluble organic acid content greater than or equal to approximately 2 percent by weight. More preferably, the liquid nicotine formulation has a water-soluble organic acid content greater than or equal to approximately 3 percent by weight. Preferably, the liquid nicotine formulation has a water-soluble organic acid content of approximately 8 percent by weight or less. More preferably, the liquid nicotine formulation has a water-soluble organic acid content of approximately 6 percent by weight or less. Preferably, the liquid nicotine formulation has a water-soluble organic acid content of between approximately 2 percent by weight and approximately 8 percent by weight. For example, the liquid nicotine formulation may have a water-soluble organic acid content of between approximately 2 percent by weight and approximately 6 percent by weight. Preferably, the liquid nicotine formulation has a water-soluble organic acid content of between approximately 3 percent by weight and approximately 8 percent by weight. For example, the liquid nicotine formulation may have a water-soluble organic acid content of between approximately 2 percent by weight and approximately 6 percent by weight. Liquid nicotine formulations may include one or more flavorings. Suitable flavorings include, but are not limited to, menthol. Preferably, the liquid nicotine formulation has a flavoring content of approximately 4 percent by weight or less. More preferably, the liquid nicotine formulation has a flavoring content of approximately 3 percent by weight or less. A cartridge for use in an aerosol generating system is also provided according to the invention; the cartridge contains a liquid nicotine formulation according to the invention. The cartridge may comprise an atomizer configured to generate an aerosol from the liquid nicotine formulation. A cartridge containing the liquid nicotine formulation and an atomizer configured to generate an aerosol from the liquid nicotine formulation may be called a “cartomizer”. The atomizer can be a thermal atomizer. As used herein with reference to the invention, the term “thermal atomizer” describes an atomizer configured to heat the liquid nicotine formulation to generate an aerosol. The cartridge can comprise any suitable type of thermal atomizer. The thermal atomizer may comprise a heater and a liquid transport element configured to transport the liquid nicotine formulation to the heater. The liquid transport element may comprise a capillary wick. The heater may comprise a heating coil. C7Q?nn / l 7Π7 / Β / Y The thermal atomizer may include an electric heater. For example, the thermal atomizer may include an electric heater comprising a resistive heating element or an inductive heating element. The atomizer can be a non-thermal atomizer. As used herein with reference to the invention, the term “non-thermal atomizer” describes an atomizer configured to generate an aerosol from the liquid nicotine formulation by means other than heating. The cartridge can comprise any suitable type of non-thermal atomizer. For example, a non-thermal atomizer can be an impact jet atomizer, an ultrasonic atomizer, or a vibrating mesh atomizer. In accordance with the invention, an aerosol generating system is further provided comprising a liquid nicotine formulation according to the invention and an atomizer configured to generate an aerosol from the liquid nicotine formulation. The atomizer can be a thermal atomizer. The aerosol generating system may comprise any suitable type of thermal atomizer. The thermal atomizer may comprise a heater and a liquid transport element configured to transport the liquid nicotine formulation to the heater. The liquid transport element may comprise a capillary wick. The heater may comprise a heating coil. The thermal atomizer may include an electric heater. For example, the thermal atomizer may include an electric heater comprising a resistive heating element or an inductive heating element. The atomizer can be a non-thermal atomizer. The aerosol generating system may comprise any suitable type of non-thermal atomizer. c^aynn / i ζηζ / E / γ For example, a non-thermal atomizer can be an impact jet atomizer, an ultrasonic atomizer, or a vibrating mesh atomizer. The aerosol generating system may comprise: a cartridge according to the invention containing the liquid nicotine formulation; and an aerosol generating device comprising a housing defining a device cavity configured to receive at least a portion of the cartridge. The aerosol generating system may comprise: a consumable cartridge according to the invention containing the liquid nicotine formulation; and a reusable aerosol generating device comprising a housing defining a device cavity configured to receive at least a portion of the cartridge. The aerosol generating device may comprise a battery and electronic control elements. The aerosol generating system may comprise: a cartridge according to the invention containing the liquid nicotine formulation and the atomizer; and an aerosol generating device comprising a housing defining a device cavity configured to receive at least a portion of the cartridge. The aerosol generating system may comprise: a cartridge according to the invention containing the liquid nicotine formulation; and an aerosol generating device comprising a housing defining a device cavity configured to receive at least a portion of the cartridge and atomizer. To avoid any doubt, the features described above in relation to one aspect of the invention may also apply to other aspects of the invention. In particular, the features described above in relation to the liquid nicotine formulation of the invention may also, where appropriate, relate to the cartridge of the invention and the aerosol generating system of the invention. Similarly, the features described C7Q7nn / l 7Π7 / Β / Y previously related to the cartridge of the invention may also be related, where appropriate, to the aerosol generating system of the invention and vice versa. The embodiments of the invention will now be described, by way of example only, with reference to the following examples: Examples 1-3 Three liquid nicotine formulations were prepared in accordance with the invention (Examples 1, 2 and 3) that have the compositions shown in Tables 2, 3 and 4. czajnn / i ζηζ / Ε / γ Example 1 Component % by weight Nicotine 5 Water 7 Vegetable glycerin water-miscible solvent 24 Propylene glycol 24 Triethyl citrate partially water-soluble solvent, immiscible in water 30 Polysorbate 80 1 Lactic acid water-soluble organic acid 7 Flavoring 2 Table 2 Example 2 Component % by weight Nicotine 2 Water 31 Vegetable glycerin water-miscible solvent 31 Triethyl citrate partially water-soluble solvent, immiscible in water 30 Polysorbate 80 1 Lactic acid water-soluble organic acid 3 Flavoring 2 Table 3 czaynn / i ζηζ / ε / γ Example 3 Component % by weight Nicotine 5 Water 7 Vegetable glycerin water-miscible solvent 24 Propylene glycol 24 Triacetin partially water-soluble solvent, immiscible in water 30 Polysorbate 80 1 Lactic acid water-soluble organic acid 7 Flavoring 2 Table 4 AF Examples Six liquid nicotine formulations were prepared in accordance with the invention (Examples A, B, C, D, E, and F) having the compositions shown in Table 5. For comparison, two liquid nicotine formulations not in accordance with the invention (Examples G and H) were also prepared having the composition shown in Table 5. The liquid nicotine formulations from Examples AH were each loaded into a cartridge for a Solaris electronic cigarette. The nicotine retention of the aerosols generated when using the cartridges in a Solaris electronic cigarette was measured using denuder tube technology essentially as described in Seeman, JI; Lipowicz, PJ; Piadé, J.-J.; Poget, L.; Sanders, EB; Snyder, JP; Trowbridge, CG, On the Deposition of Volatiles and Semivolatiles from Cigarette Smoke Aerosols: Relative Rates of Transfer of Nicotine and Ammonia from Particles to the Gas Phase.Chemical Research in Toxicology 2004, 17, 10SOI 037, with the following modifications: the aerosol was drawn out rather than pushed; 55 ml puffs were used instead of 35 ml puffs; the denuder used was a 30 m Tygon® tube; the difference in nicotine yield was measured by comparing the amount collected from the product on a Cambridge pad with and without the Tygon® tube, rather than measuring the amount collected with the denuder and with the Cambridge pad placed after the denuder. For comparison, the nicotine retention of the smoke generated by burning a conventional cigarette was also measured (Example I). The results are shown in Table 5. As shown in Table 5, aerosols generated from liquid nicotine formulations according to the invention (Examples AF) provide nicotine retentions greater than 40 percent. In contrast, aerosols generated from liquid formulations not according to the invention (Examples G and H) provide lower nicotine retentions of less than 30 percent. The nicotine retention properties of the aerosols generated from the liquid nicotine formulations according to the invention (Examples AF) are at least 13.5 times C7Q?nn / l 7Π7 / B / Y superior to the liquid formulation not in conformity with the invention comprising a partially water-soluble solvent, immiscible in water having a water solubility at 20 °C of between approximately 20 mg / ml and approximately 100 mg / ml or a water-soluble organic acid (Example G). The nicotine retention properties of aerosols generated from liquid nicotine formulations according to the invention (Examples AF) are at least approximately 1.5 times higher than the liquid formulation not according to the invention comprising a water-soluble organic acid, but not comprising a partially water-soluble, water-immiscible solvent having a water solubility at 20 °C of between approximately 20 mg / ml and approximately 100 mg / ml (Example H). The nicotine retention properties of aerosols generated from liquid nicotine formulations according to the invention (Examples AF), comprising a partially water-soluble, water-immiscible solvent having a water solubility at 20°C of between approximately 20 mg / ml and approximately 100 mg / ml, are similar to the nicotine retention properties of smoke generated from a conventional cigarette (Example I). czaynn / i ζηζ / E / γ — • ι t 1' í » 36-39 % X 10 O CN 34.7 34.7 O o 5.6 o co sP to 01 ο 10 o 37.5 37.5 QO o 1 % U. 4.2 01 04 o 4.3 53.5 D 80 8.7 ίο 05 Ó 04 o 4.3 O s Ο 2.7 40 45 4.2 01 04 4.3 o to Μ 2.4 r 8.7 1.5 0.9 CN 4.3 or 73.7 Ο α Ε ω UI water-miscible solvent partially water-soluble solvent, water-immiscible organic acid Nicotine (wt%) Gycerine (wt%) Water (wt% (wt%) Pmpiiengglycol (wt%) Triacetin (wt%) Methyl Citrate (wt%) Lactic Acid (wt%) Levulinic Acid (wt%) Nicotine Retention (%) “η m « czajnn / i ζηζ / Ε / γίΛΐ

Claims

1. A liquid nicotine formulation for use in an aerosol generating system, the liquid nicotine formulation comprising: water; and one or more partially water-soluble, water-immiscible solvents having a water solubility at 20°C of between approximately 20 mg / ml and approximately 100 mg / ml, wherein the liquid nicotine formulation has a water content greater than or equal to approximately 5 percent by weight and a partially water-soluble, water-immiscible solvent content of between approximately 2 percent by weight and approximately 30 percent by weight.

2. A liquid nicotine formulation according to claim 1, comprising one or more water-insoluble, water-immiscible solvents having a water solubility at 20°C less than or equal to approximately 5 mg / ml.

3. A liquid nicotine formulation for use in an aerosol generating system, the liquid nicotine formulation comprising: water; and one or more partially water-soluble, water-immiscible solvents having a partition coefficient (log P) at 20°C of between approximately 0.05 and approximately 0.5, wherein the liquid nicotine formulation has a water content greater than or equal to approximately 5 percent by weight and a partially water-soluble, water-immiscible solvent content of between approximately 2 percent by weight and approximately 30 percent by weight. czajnn / i ζηζ / E / γ 4. A liquid nicotine formulation according to claim 3 comprising one or more water-insoluble, water-immiscible solvents having a partition coefficient (log P) at 20 °C greater than approximately 5.

5. A liquid nicotine formulation according to any of claims 1 to 4, having a partially water-soluble, water-immiscible solvent content greater than or equal to approximately 2.5 percent by weight.

6. A liquid nicotine formulation according to any of claims 1 to 5 wherein the one or more partially water-soluble, water-immiscible solvents are selected from the group consisting of triacetin and triethyl citrate.

7. A liquid nicotine formulation according to any of claims 1 to 6, comprising water and one or more water-miscible solvents.

8. A liquid nicotine formulation according to claim 7, having a total water and water-miscible solvent content greater than or equal to approximately 60 percent by weight.

9. A liquid nicotine formulation according to claim 7 or 8, wherein the one or more water-miscible solvents are one or more water-miscible polyhydric alcohols selected from the group consisting of 1,3-butanediol, glycerin, propylene glycol, and triethylene glycol.

10. A liquid nicotine formulation according to any of claims 1 to 9 comprising one or more solid emulsifiers. czaynn / i ζηζ / E / γ 11. A liquid nicotine formulation according to any of claims 1 to 10 comprising one or more water-soluble organic acids, wherein the liquid nicotine formulation has a water-soluble organic acid content greater than or equal to approximately 2 percent by weight.

12. A cartridge for use in an aerosol generating system, the cartridge containing a liquid nicotine formulation in accordance with any of claims 1 to 11.

13. A cartridge according to claim 12, comprising an atomizer 10 configured to generate an aerosol from the liquid nicotine formulation.

14. An aerosol generating system comprising: a liquid nicotine formulation according to any of claims 1 to 11; and 15 an atomizer configured to generate an aerosol from the liquid nicotine formulation.