LOW VISCOSITY LIQUID NICOTINE FORMULATION

Abstract

A liquid nicotine formulation for use in an aerosol generating system, the liquid nicotine formulation comprising one or more water-miscible solvents and having a viscosity at 20°C less than or equal to approximately 20 mPa·s, wherein the liquid nicotine formulation has a water-miscible solvent content of between approximately 10 percent by weight and approximately 50 percent by weight. A liquid nicotine formulation for use in an aerosol generating system, the liquid nicotine formulation comprising glycerin and having a viscosity at 20°C less than or equal to approximately 20 mPa·s, wherein the liquid nicotine formulation has a glycerin content greater than or equal to approximately 6 percent by weight. A cartridge for use in an aerosol generating system, the cartridge containing the liquid nicotine formulation.An aerosol generating system comprising a liquid nicotine formulation and an atomizer configured to generate an aerosol from the liquid nicotine formulation.

Description

LOW VISCOSITY LIQUID NICOTINE FORMULATION FIELD OF INVENTION The invention relates to a liquid nicotine formulation for use in an aerosol generating system. In particular, the invention relates to a liquid nicotine formulation for use in an aerosol generating system comprising a non-thermal atomizer. 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, comprising 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. 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. In contrast, nicotine adsorption in the upper respiratory tract is slower and less efficient. Upper respiratory tract nicotine adsorption may also be perceived as having a harsh sensory experience and inducing irritation of the mouth and throat. Qza / nn / Lznz / e / YiAi The pulmonary deposition characteristics, and therefore the efficacy, of the inhalable aerosol generated from the liquid nicotine formulation depend on the size of the aerosol particles or droplets. Typically, a small particle or droplet size is desired to maximize pulmonary nicotine delivery and retention. In particular, a particle or droplet size of approximately 5 microns in diameter or less is believed to be suitable for maximizing pulmonary delivery. To improve nicotine delivery and pulmonary retention, it would be advantageous to provide a liquid nicotine formulation for use in an aerosol generating system that facilitates the generation of an aerosol with a small droplet size. For example, it would be advantageous to provide a liquid nicotine formulation for use in an aerosol generating system that facilitates the generation of an aerosol with a particle or droplet size less than or equal to approximately 5 microns in diameter. BRIEF DESCRIPTION OF THE INVENTION According to the invention, a liquid nicotine formulation is provided for use in an aerosol generating system; the liquid nicotine formulation has a viscosity at 20°C less than or equal to approximately 20 millipascal seconds (mPa s). In accordance with the invention, a cartridge is also provided for use in an aerosol generating system, the cartridge containing a liquid nicotine formulation having a viscosity at 20°C less than or equal to approximately 20 millipascal seconds (mPas). According to the invention, an aerosol generating system is further provided comprising: a liquid nicotine formulation having a viscosity at 20 °C less than or equal to approximately 20 millipascal seconds (mPa s); 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. QZQ / nn / Lznz / e / YiAi 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 freebase nicotine or the amount of protonated nicotine, respectively. When used in an aerosol generating system, the low viscosity of the liquid nicotine formulation according to the invention facilitates the generation of an inhalable aerosol with a small particle or droplet size. This can advantageously improve the delivery and retention of nicotine to the lungs. As discussed below, the use of the liquid nicotine formulation according to the invention in an aerosol generating system comprising a non-thermal atomizer is particularly advantageous. Liquid nicotine formulations may comprise natural nicotine or synthetic nicotine. Unless otherwise stated, the viscosity values ​​quoted herein are the viscosity of an 8 milliliter (mi) sample volume of liquid nicotine formulation measured using a Brookfield RVDVII +Pro viscometer equipped with a Brookfield small sample adapter comprising an SC4-13R cylindrical sample chamber and an SC4-21 cylindrical spindle at a speed of 100 revolutions per minute (rpm). The liquid nicotine formulation may have a viscosity at 20 °C less than or equal to approximately 18 mPa or less than or equal to approximately 16 mPa s. Preferably, the liquid nicotine formulation has a viscosity at 20 °C less than or equal to approximately 14 mPa s. More preferably, the liquid nicotine formulation has a viscosity at 20 °C less than or equal to approximately 12 mPa s. For example, the liquid nicotine formulation may have a viscosity at 20 °C less than or equal to approximately 10 mPa s. Preferably, the liquid nicotine formulation has a viscosity at 20 °C greater than or equal to approximately 0.75 mPa s. More preferably, the nicotine formulation QZQ / nn / Lznz / e / YiAi liquid has a viscosity at 20 °C greater than or equal to approximately 1 mPa s. For example, the liquid nicotine formulation may have a viscosity at 20 °C greater than or equal to approximately 1.25 mPa, greater than or equal to approximately 1.5 mPa or greater than or equal to approximately 1.75 mPa s. Liquid nicotine formulations can have a viscosity at 20°C of between approximately 0.75 mPa·s and approximately 18 mPa·s. For example, liquid nicotine formulations can have a viscosity at 20°C of between approximately 1 mPa·s and approximately 18 mPa·s, between approximately 1.25 mPa·s and approximately 18 mPa·s, between approximately 1.5 mPa·s and approximately 18 mPa·s, or between approximately 1.75 mPa·s and approximately 18 mPa·s. Liquid nicotine formulations can have a viscosity at 20°C of between approximately 0.75 mPa·s and approximately 16 mPa·s. For example, liquid nicotine formulations can have a viscosity at 20°C of between approximately 1 mPa·s and approximately 16 mPa·s, between approximately 1.25 mPa·s and approximately 16 mPa·s, between approximately 1.5 mPa·s and approximately 16 mPa·s, or between approximately 1.75 mPa·s and approximately 16 mPa·s. Preferably, the liquid nicotine formulation has a viscosity at 20 °C of between approximately 0.75 mPa·s and approximately 14 mPa·s. For example, the liquid nicotine formulation may have a viscosity at 20 °C of between approximately 1 mPa·s and approximately 14 mPa·s, between approximately 1.25 mPa·s and approximately 14 mPa·s, between approximately 1.5 mPa·s and approximately 14 mPa·s, or between approximately 1.75 mPa·s and approximately 14 mPa·s. Preferably, the liquid nicotine formulation has a viscosity at 20°C of between approximately 0.75 mPa s and approximately 12 mPa s. For example, the liquid nicotine formulation may have a viscosity at 20°C of between approximately 1 mPa and approximately 12 mPa s, between approximately 1.25 mPa s and approximately 12 mPa s, between approximately 1.5 mPa and approximately 12 mPa, or between approximately 1.75 mPa s and approximately 12 mPa s. QZQ / nn / Lznz / e / YiAi Liquid nicotine formulations can have a viscosity at 20°C of between approximately 0.75 mPas and approximately 10 mPa·s. For example, liquid nicotine formulations can have a viscosity at 20°C of between approximately 1 mPas and approximately 10 mPas, between approximately 1.25 mPa·s and approximately 10 mPas, between approximately 1.5 mPas and approximately 10 mPa·s, or between approximately 1.75 mPa·s and approximately 10 mPa·s. Liquid nicotine formulations may have a nicotine content greater than or equal to approximately 0.5 percent by weight. 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. 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 of approximately 10 percent by weight or less. The liquid nicotine formulation may have a nicotine content of approximately 8 percent by weight or less. 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. Liquid nicotine formulations can have a nicotine content of between approximately 0.5 percent by weight and approximately 10 percent by weight. For example, liquid nicotine formulations can 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. QZQ / nn / Lznz / e / YiAi 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 might 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. Preferably, the liquid nicotine formulation comprises water. The liquid nicotine formulation may have a water content greater than or equal to approximately 10 percent by weight, greater than or equal to approximately 15 percent by weight, or greater than or equal to approximately 20 percent by weight. Preferably, the liquid nicotine formulation has a water content greater than or equal to approximately 25 percent by weight. More preferably, the liquid nicotine formulation has a water content greater than or equal to approximately 30 percent by weight. For example, the liquid nicotine formulation may have a water content greater than or equal to approximately 35 percent by weight or greater than or equal to approximately 40 percent by weight. The inclusion of at least approximately 25 percent by weight of water advantageously facilitates obtaining a liquid nicotine formulation that has a viscosity at 20 °C less than or equal to approximately 20 mPa s. Preferably, the liquid nicotine formulation has a water content of approximately 90 percent by weight or less. More preferably, the liquid nicotine formulation has a water content of approximately 85 percent by weight or less. QZQ / nn / Lznz / e / YiAi For example, the liquid nicotine formulation may have a water content less than or equal to approximately 80 percent by weight, less than or equal to approximately 75 percent by weight, less than or equal to approximately 70 percent by weight, or less than or equal to QZQ / nn / Lznz / e / Yi / u approximately 65 weight percent. Liquid nicotine formulations can have a water content of between approximately 10 percent by weight and approximately 90 percent by weight. For example, liquid nicotine formulations can have a water content of between approximately [missing information] and approximately [missing information] by weight, between approximately [missing information] and approximately [missing information] by weight, between approximately [missing information] and approximately [missing information] by weight, between approximately [missing information] and approximately 70 percent by weight, or between approximately 10 percent by weight and approximately 65 percent by weight. Liquid nicotine formulations can have a water content of between approximately 15 percent by weight and approximately 90 percent by weight. For example, liquid nicotine formulations can have a water content of 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. For example, liquid nicotine formulations can have a water content of between approximately 20 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. Preferably, the liquid nicotine formulation has a water content of between approximately 25 percent by weight and approximately 90 percent by weight. For example, the liquid nicotine formulation may have a water content of between approximately 25 percent by weight and approximately 85 percent by weight, 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. Ideally, liquid nicotine formulations have a water content of between approximately 30 percent and approximately 90 percent by weight. For example, liquid nicotine formulations may have a water content of between approximately 30 percent and approximately 85 percent by weight, between approximately 30 percent and approximately 80 percent by weight, between approximately 30 percent and approximately 75 percent by weight, between approximately 30 percent and approximately 70 percent by weight, or between approximately 30 percent 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. For example, liquid nicotine formulations can have a water content of between approximately 35 percent by weight and approximately 85 percent by weight, 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. Liquid nicotine formulations can have a water content of between approximately 40 percent and approximately 90 percent by weight. For example, liquid nicotine formulations can have a water content of between approximately 40 percent and approximately 85 percent by weight. QZQ / nn / Lznz / e / YiAi approximately 40 percent by weight and approximately 80 percent by weight, between approximately 40 percent by weight and approximately 75 percent by weight, between approximately 40 percent by weight and approximately 70 percent by weight or between approximately 40 percent by weight and approximately 65 percent by weight. Preferably, the liquid nicotine formulation comprises one or more water-miscible solvents. 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. Preferably, the liquid nicotine formulation comprises water and one or more water-miscible solvents. In combination, water and one or more water-miscible solvents can advantageously help to dissolve and stabilize the polar and ionic components of the liquid nicotine formulation. Preferably, the liquid nicotine formulation has a water-miscible solvent content greater than or equal to approximately 5 percent by weight. More preferably, the liquid nicotine formulation has a water-miscible solvent content greater than or equal to approximately 10 percent by weight. For example, the liquid nicotine formulation may have a water-miscible solvent content greater than or equal to approximately 15 percent by weight, greater than or equal to approximately 20 percent by weight, or greater than or equal to approximately 25 percent by weight. The liquid nicotine formulation may have a water miscible solvent content less than or equal to approximately 80 percent by weight, less than or equal to approximately 75 percent by weight, or less than or equal to approximately 70 percent by weight. Preferably, the liquid nicotine formulation has a water-miscible solvent content of approximately 60 percent by weight or less. More preferably, the liquid nicotine formulation has a water-miscible solvent content of approximately 50 percent by weight or less. For example, the liquid nicotine formulation azQ / nn / Lznz / e / YiAi may have a water-miscible solvent content of approximately 40 percent by weight or less. The liquid nicotine formulation may have a water-miscible solvent 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, or between approximately 5 percent by weight and approximately 70 percent by weight. Preferably, the liquid nicotine formulation has a water-miscible solvent content of between approximately 5 percent and approximately 60 percent by weight. For example, the liquid nicotine formulation may have a water-miscible solvent content of between approximately 5 percent and approximately 50 percent. Qza / nn / Lznz / e / YiAi one hundred percent by weight or between approximately 5 percent by weight and approximately 40 percent by weight. The liquid nicotine formulation may have a water miscible solvent 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, or between approximately 10 percent by weight and approximately 70 percent by weight. Preferably, the liquid nicotine formulation has a water-miscible solvent content of between approximately 10 percent by weight and approximately 60 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 50 percent by weight, or between approximately 10 percent by weight and approximately 40 percent by weight. The liquid nicotine formulation may have a water miscible solvent content of between approximately between approximately between approximately between approximately between approximately percent by weight percent by weight percent by weight percent by weight and approximately and approximately and approximately and approximately percent by weight, percent by weight, percent by weight 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 QZQ / nn / Lznz / e / YiAi between approximately between approximately between approximately between approximately percent by weight percent by weight percent by weight percent by weight and approximately and approximately and approximately and approximately percent by weight percent by weight percent by weight 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 between approximately between approximately between approximately between approximately percent by weight percent by weight percent by weight percent by weight and approximately and approximately and approximately and approximately percent by weight percent by weight percent by weight percent by weight percent 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 where the liquid nicotine formulation comprises water and one or more water-miscible solvents, the liquid nicotine formulation may have a combined water and water-miscible solvent content greater than or equal to approximately 50 percent by weight, greater than or equal to approximately 55 percent by weight, greater than or equal to approximately 60 percent by weight, greater than or equal to approximately 65 percent by weight, or greater than or equal to approximately 70 percent by weight. In embodiments where the liquid nicotine formulation comprises water and one or more water-miscible solvents, preferably, the liquid nicotine formulation has a combined water and water-miscible solvent content of approximately 75 percent by weight or greater. More preferably, the liquid nicotine formulation has a combined water and water-miscible solvent content of 80 percent by weight or greater. Most preferably, the liquid nicotine formulation has a combined water and water-miscible solvent content of approximately 85 percent by weight or greater. In embodiments where the liquid nicotine formulation comprises water and one or more water-miscible solvents, preferably, the weight percent of the water content of the liquid nicotine formulation is at least approximately 0.8 times the weight percent of the water-miscible solvent content of the liquid nicotine formulation. More preferably, the weight percent of the water content of the liquid nicotine formulation is at least approximately 1.5 times the weight percent of the water-miscible solvent content of the liquid nicotine formulation. That is, preferably, the ratio of the weight percent of water content to the weight percent of water-miscible solvent content of the liquid nicotine formulation is greater than or equal to approximately 0.8, more preferably greater than or equal to approximately 1.5. The weight percent of water content in the liquid nicotine formulation may be at least approximately 2 times the weight percent of water-miscible solvent content in the liquid nicotine formulation, at least approximately 3 times the weight percent of water-miscible solvent content in the liquid nicotine formulation, at least approximately 4 times the weight percent of water-miscible solvent content in the liquid nicotine formulation, or at least 5 times the weight percent of water-miscible solvent content in the liquid nicotine formulation. That is, the ratio of the weight percent of water content to the weight percent of water-miscible solvent content of the liquid nicotine formulation may be greater than or equal to approximately 2, greater than or equal to approximately 3, greater than or equal to approximately 4, or greater than or equal to approximately 5. Preferably, the weight percent water content of the liquid nicotine formulation is less than or equal to approximately 9 times the weight percent water-miscible solvent in the liquid nicotine formulation. More preferably, the weight percent water content of the liquid nicotine formulation is less than or equal to QZQ / nn / Lznz / e / YiAi approximately 8 times the weight percent of the water miscible solvent content of the liquid nicotine formulation. That is, preferably, the ratio of the weight percent of water content to the weight percent of water-miscible solvent content of the liquid nicotine formulation is less than or equal to approximately 9, more preferably less than or equal to approximately 8. The weight percent water content of the liquid nicotine formulation may be less than or equal to approximately 7 times the weight percent water-miscible solvent content of the liquid nicotine formulation. In other words, the ratio of the weight percent of water content to the weight percent of water-miscible solvent content of the liquid nicotine formulation may be less than or equal to approximately 7. Preferably, the weight percent water content of the liquid nicotine formulation is between approximately 0.8 times and approximately 9 times the weight percent water-miscible solvent content of the liquid nicotine formulation. For example, the weight percent water content of the liquid nicotine formulation may be between approximately 0.8 times and approximately 8 times the weight percent water-miscible solvent content of the liquid nicotine formulation, or between approximately 0.8 times and approximately 7 times the weight percent water-miscible solvent content of the liquid nicotine formulation. Ideally, the weight percent water content of the liquid nicotine formulation is between approximately 1.5 times and approximately 9 times the weight percent water-miscible solvent content of the liquid nicotine formulation. For example, the weight percent water content of the liquid nicotine formulation may be between approximately 1.5 times and approximately 8 times the weight percent water-miscible solvent content of the liquid nicotine formulation, or between approximately 1.5 times and approximately 7 times the weight percent water-miscible solvent content of the liquid nicotine formulation. QZQ / nn / Lznz / e / YiAi The weight percent of water content in the liquid nicotine formulation can range from approximately 2 times to approximately 9 times the weight percent of water-miscible solvent content in the liquid nicotine formulation. For example, the weight percent of water content in the liquid nicotine formulation can range from approximately 2 times to approximately 8 times the weight percent of water-miscible solvent content in the liquid nicotine formulation, or from approximately 2 times to approximately 7 times the weight percent of water-miscible solvent content in the liquid nicotine formulation. The weight percent of water content in the liquid nicotine formulation can range from approximately 3 times to approximately 9 times the weight percent of water-miscible solvent content in the liquid nicotine formulation. For example, the weight percent of water content in the liquid nicotine formulation can range from approximately 3 times to approximately 8 times the weight percent of water-miscible solvent content in the liquid nicotine formulation, or from approximately 3 times to approximately 7 times the weight percent of water-miscible solvent content in the liquid nicotine formulation. The weight percent of water content in the liquid nicotine formulation can be between approximately 4 times and approximately 9 times the weight percent of water-miscible solvent content in the liquid nicotine formulation. For example, the weight percent of water content in the liquid nicotine formulation can be between approximately 4 times and approximately 8 times the weight percent of water-miscible solvent content in the liquid nicotine formulation, or between approximately 4 times and approximately 7 times the weight percent of water-miscible solvent content in the liquid nicotine formulation. The weight percent of water content in the liquid nicotine formulation can be between approximately 5 times and approximately 9 times the weight percent of water-miscible solvent content in the liquid nicotine formulation. For example, the weight percent of water content in the liquid nicotine formulation can be between approximately 5 times and approximately 8 times the weight percent of water-miscible solvent content in the liquid nicotine formulation, or between approximately 5 times and approximately 7 times the weight percent of water-miscible solvent content in the liquid nicotine formulation. The one or more water-miscible solvents can be one or more water-miscible polyhydric alcohols. Preferably, the liquid nicotine formulation comprises 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. Preferably, the liquid nicotine formulation comprises water and one or more water-miscible polyhydric alcohols. Preferably, the liquid nicotine formulation has a water-miscible polyhydric alcohol content greater than or equal to approximately 5 percent by weight. More preferably, the liquid nicotine formulation has a water-miscible polyhydric alcohol content greater than or equal to approximately 10 percent by weight. For example, the liquid nicotine formulation may have a water-miscible polyhydric alcohol content greater than or equal to approximately 15 percent by weight, greater than or equal to approximately 20 percent by weight, or greater than or equal to approximately 25 percent by weight. The liquid nicotine formulation may have a water-miscible polyhydric alcohol content less than or equal to approximately 80 percent by weight, less than or equal to approximately 75 percent by weight, or less than or equal to approximately 70 percent by weight. Preferably, the liquid nicotine formulation has a water-miscible polyhydric alcohol content of approximately 60 percent or less by weight. More preferably, the liquid nicotine formulation has a polyhydric alcohol content QZQ / nn / Lznz / e / YiAi water-miscible at approximately 50 percent by weight or less. For example, the liquid nicotine formulation may have a water-miscible polyhydric alcohol content of approximately 40 percent by weight or less. The liquid nicotine formulation may have a water-miscible polyhydric alcohol 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, or between approximately 5 percent by weight and approximately 70 percent by weight. Preferably, the liquid nicotine formulation has a water-miscible polyhydric alcohol content of between approximately 5 percent by weight and approximately 60 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 50 percent by weight or between approximately 5 percent by weight and approximately 40 percent by weight. The liquid nicotine formulation may have a water-miscible polyhydric alcohol 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, or between approximately 10 percent by weight and approximately 70 percent by weight. Preferably, the liquid nicotine formulation has a water-miscible polyhydric alcohol content of between approximately 10 percent by weight and approximately 60 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 50 percent by weight, or between approximately 10 percent by weight and approximately 40 percent by weight. The liquid nicotine formulation may have a water-miscible polyhydric alcohol 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 water-miscible polyhydric alcohol content of between approximately 20 percent by weight and approximately 80 percent by weight, between approximately percent by weight and approximately percent by weight, between approximately percent by weight and approximately percent by weight, between approximately percent by weight and approximately percent by weight, between approximately percent by weight and approximately 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 80 percent by weight, between approximately 25 percent by weight, between approximately 25 percent by weight, between approximately 25 percent by weight, between approximately 25 percent by weight, between approximately 25 percent by weight and approximately 75 percent by weight and approximately 70 percent by weight and approximately 60 percent by weight and approximately 50 percent by weight, or between approximately 25 percent by weight and approximately 40 percent by weight. 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, greater than or equal to approximately 55 percent by weight, greater than or equal to approximately 60 percent by weight, greater than or equal to approximately 65 percent by weight, or greater than or equal to approximately 70 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 greater than or equal to approximately 75 percent by weight. More preferably, the liquid nicotine formulation has a combined water and water-miscible polyhydric alcohol content greater than or equal to 80 percent by weight. Most preferably, the liquid nicotine formulation has a combined water and water-miscible polyhydric alcohol content greater than or equal to approximately 85 percent by weight. In embodiments where the liquid nicotine formulation comprises water and one or more water-miscible polyhydric alcohols, preferably, the weight percent of the water content of the liquid nicotine formulation is at least approximately 0.8 times the weight percent of the water-miscible polyhydric alcohol content of the liquid nicotine formulation. More preferably, the weight percent of the water content of the liquid nicotine formulation is at least approximately 1.5 times the weight percent of the water-miscible polyhydric alcohol content of the liquid nicotine formulation. That is, preferably, the ratio of the weight percent of water content to the weight percent of water-miscible polyhydric alcohol content of the liquid nicotine formulation is greater than or equal to approximately 0.8, more preferably greater than or equal to approximately 1.5. The weight percent of water content in the liquid nicotine formulation may be at least approximately 2 times the weight percent of water-miscible polyhydric alcohol content in the liquid nicotine formulation, at least approximately 3 times the weight percent of water-miscible polyhydric alcohol in the liquid nicotine formulation, at least approximately 4 times the weight percent of water-miscible polyhydric alcohol in the liquid nicotine formulation, or at least approximately 5 times the weight percent of water-miscible polyhydric alcohol in the liquid nicotine formulation. QZQ / nn / Lznz / e / YiAi That is, the ratio of the weight percent of water content to the weight percent of water-miscible polyhydric alcohol content of the liquid nicotine formulation may be greater than or equal to approximately 2, greater than or equal to approximately 3, greater than or equal to approximately 4, or greater than or equal to approximately 5. Preferably, the weight percent water content of the liquid nicotine formulation is less than or equal to approximately 9 times the weight percent water-miscible polyhydric alcohol content of the liquid nicotine formulation. More preferably, the weight percent water content of the liquid nicotine formulation is less than or equal to approximately 8 times the weight percent water-miscible polyhydric alcohol content of the liquid nicotine formulation. That is, preferably, the ratio of the weight percent of water content to the weight percent of water-miscible polyhydric alcohol content of the liquid nicotine formulation is less than or equal to approximately 9, more preferably less than or equal to approximately 8. The weight percent of water content in the liquid nicotine formulation may be less than or equal to approximately 7 times the weight percent of water-miscible polyhydric alcohol content in the liquid nicotine formulation. In other words, the ratio of the weight percent of water content to the weight percent of water-miscible polyhydric alcohol content of the liquid nicotine formulation may be less than or equal to approximately 7. Preferably, the weight percent water content of the liquid nicotine formulation is between approximately 0.8 times and approximately 9 times the weight percent water-miscible polyhydric alcohol content of the liquid nicotine formulation. For example, the weight percent water content of the liquid nicotine formulation may be between approximately 0.8 times and approximately 8 times the weight percent water-miscible polyhydric alcohol content of the liquid nicotine formulation, or between approximately 0.8 times and approximately 7 times the weight percent water content of the liquid nicotine formulation. QZQ / nn / Lznz / e / YiAi by weight of the water miscible polyhydric alcohol content of the liquid nicotine formulation. Preferably, the weight percent water content of the liquid nicotine formulation is between approximately 1.5 times and approximately 9 times the weight percent water-miscible polyhydric alcohol content of the liquid nicotine formulation. For example, the weight percent water content of the liquid nicotine formulation may be between approximately 1.5 times and approximately 8 times the weight percent water-miscible polyhydric alcohol content of the liquid nicotine formulation, or between approximately 1.5 times and approximately 7 times the weight percent water-miscible polyhydric alcohol content of the liquid nicotine formulation. The weight percent of water content in the liquid nicotine formulation can range from approximately 2 times to approximately 9 times the weight percent of water-miscible polyhydric alcohol content in the liquid nicotine formulation. For example, the weight percent of water content in the liquid nicotine formulation can range from approximately 2 times to approximately 8 times the weight percent of water-miscible polyhydric alcohol content in the liquid nicotine formulation, or from approximately 2 times to approximately 7 times the weight percent of water-miscible polyhydric alcohol content in the liquid nicotine formulation. The weight percent of water content in the liquid nicotine formulation can be between approximately 3 times and approximately 9 times the weight percent of water-miscible polyhydric alcohol content in the liquid nicotine formulation. For example, the weight percent of water content in the liquid nicotine formulation can be between approximately 3 times and approximately 8 times the weight percent of water-miscible polyhydric alcohol content in the liquid nicotine formulation, or between approximately 3 times and approximately 7 times the weight percent of water-miscible polyhydric alcohol content in the liquid nicotine formulation. QZQ / nn / Lznz / e / YiAi The weight percent of water content in the liquid nicotine formulation can be between approximately 4 times and approximately 9 times the weight percent of water-miscible polyhydric alcohol content in the liquid nicotine formulation. For example, the weight percent of water content in the liquid nicotine formulation can be between approximately 4 times and approximately 8 times the weight percent of water-miscible polyhydric alcohol content in the liquid nicotine formulation, or between approximately 4 times and approximately 7 times the weight percent of water-miscible polyhydric alcohol content in the liquid nicotine formulation. The weight percent of water content in the liquid nicotine formulation can be between approximately 5 times and approximately 9 times the weight percent of water-miscible polyhydric alcohol content in the liquid nicotine formulation. For example, the weight percent of water content in the liquid nicotine formulation can be between approximately 5 times and approximately 8 times the weight percent of water-miscible polyhydric alcohol content in the liquid nicotine formulation, or between approximately 5 times and approximately 7 times the weight percent of water-miscible polyhydric alcohol content in the liquid nicotine formulation. Preferably, the liquid nicotine formulation comprises one or more water-miscible polyhydric alcohols selected from the group consisting of 1,3-butanediol, glycerin, propylene glycol, and triethylene glycol. Most preferably, the liquid nicotine formulation comprises water and one or more water-miscible polyhydric alcohols selected from the group consisting of 1,3-butanediol, glycerin, propylene glycol, and triethylene glycol. Preferably, the liquid nicotine formulation comprises glycerin. Preferably, the liquid nicotine formulation comprises vegetable glycerin. Preferably, the liquid nicotine formulation comprises water and glycerin. Preferably, the liquid nicotine formulation comprises water and vegetable glycerin. Preferably, the liquid nicotine formulation comprises glycerin and propylene glycol. QZQ / nn / Lznz / e / YiAi Most preferably, the liquid nicotine formulation comprises vegetable glycerin and propylene glycol. Preferably, the liquid nicotine formulation comprises water, glycerin, and propylene glycol. More preferably, the liquid nicotine formulation comprises water, vegetable glycerin, and propylene glycol. In embodiments where the liquid nicotine formulation comprises one or both of glycerin and propylene glycol, preferably, the liquid nicotine formulation has a combined glycerin and propylene glycol content greater than or equal to approximately 5 percent by weight. More preferably, the liquid nicotine formulation has a combined glycerin and propylene glycol content greater than or equal to approximately 10 percent by weight. For example, the liquid nicotine formulation may have a combined glycerin and propylene glycol content greater than or equal to approximately 15 percent by weight, greater than or equal to approximately 20 percent by weight, or greater than or equal to approximately 25 percent by weight. In embodiments where the liquid nicotine formulation comprises one or both 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, less than or equal to approximately 75 percent by weight, or less than or equal to approximately 70 percent by weight. In embodiments where the liquid nicotine formulation comprises one or both of glycerin and propylene glycol, preferably, the liquid nicotine formulation has a combined glycerin and propylene glycol content of approximately 60 percent by weight or less. More preferably, the liquid nicotine formulation has a combined glycerin and propylene glycol content of approximately 50 percent by weight or less. For example, the liquid nicotine formulation may have a combined glycerin and propylene glycol content of approximately 40 percent by weight or less. In forms where the liquid nicotine formulation comprises one or both of glycerin and propylene glycol, the liquid nicotine formulation may have a content QZQ / nn / Lznz / e / YiAi combined glycerin and propylene glycol 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, or between approximately 5 percent by weight and approximately 70 percent by weight. In embodiments where the liquid nicotine formulation comprises one or both 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 60 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 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 both 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, between approximately 10 percent by weight and approximately 75 percent by weight, or between approximately 10 percent by weight and approximately 70 percent by weight. Preferably, the liquid nicotine formulation has a combined glycerin and propylene glycol content of between approximately 10 percent and approximately 60 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 50 percent by weight, or between approximately 10 percent and approximately 40 percent by weight. The liquid nicotine formulation may have a combined glycerin and propylene glycol content of between approximately 15 percent by weight, between approximately 15 percent by weight, between approximately 15 percent by weight, between approximately 15 percent by weight and approximately 80 percent by weight and approximately 75 percent by weight and approximately 70 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 percent by weight, between approximately 20 percent by weight and approximately percent by weight, between approximately 20 percent by weight and approximately percent by weight, between approximately 20 percent by weight and approximately percent by weight, between approximately 20 percent by weight and approximately percent by weight, between approximately 20 percent by weight and approximately 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 25 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 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. QZQ / nn / Lznz / e / YiAi In embodiments where the liquid nicotine formulation comprises water and one or both 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, greater than or equal to approximately 55 percent by weight, greater than or equal to approximately 60 percent by weight, greater than or equal to approximately 65 percent by weight, or greater than or equal to approximately 70 percent by weight. In embodiments where the liquid nicotine formulation comprises water and one or both 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 75 percent by weight. More preferably, the liquid nicotine formulation has a combined content of water, glycerin, and propylene glycol greater than or equal to 80 percent by weight. Most preferably, the liquid nicotine formulation has a combined content of water, glycerin, and propylene glycol greater than or equal to approximately 85 percent by weight. In embodiments where the liquid nicotine formulation comprises water and one or both of glycerin and propylene glycol, preferably, the weight percent of the water content of the liquid nicotine formulation is at least approximately 0.8 times the combined weight percent of the glycerin and propylene glycol content of the liquid nicotine formulation. More preferably, the weight percent of the water content of the liquid nicotine formulation is at least approximately 1.5 times the combined weight percent of the glycerin and propylene glycol content of the liquid nicotine formulation. That is, preferably, the ratio of the weight percent of water content to the combined weight percent of glycerin and propylene glycol content of the liquid nicotine formulation is greater than or equal to approximately 0.8, more preferably greater than or equal to approximately 1.5. The weight percent of water content in the liquid nicotine formulation may be at least approximately 2 times the combined weight percent of glycerin and propylene glycol content in the liquid nicotine formulation, at least approximately 3 times the QZQ / nn / Lznz / e / YiAi percent combined weight of the glycerin and propylene glycol content of the liquid nicotine formulation, at least approximately 4 times the percent combined weight of the glycerin and propylene glycol content of the liquid nicotine formulation or at least approximately 5 times the percent combined weight of the glycerin and propylene glycol content of the liquid nicotine formulation. That is, the ratio of the weight percent of water content to the combined weight percent of glycerin and propylene glycol content of the liquid nicotine formulation may be greater than or equal to approximately 2, greater than or equal to approximately 3, greater than or equal to approximately 4, or greater than or equal to approximately 5. Preferably, the weight percent water content of the liquid nicotine formulation is less than or equal to approximately 9 times the combined weight percent glycerin and propylene glycol content of the liquid nicotine formulation. More preferably, the weight percent water content of the liquid nicotine formulation is less than or equal to approximately 8 times the combined weight percent glycerin and propylene glycol content of the liquid nicotine formulation. That is, preferably, the ratio of the weight percent of water content to the combined weight percent of glycerin and propylene glycol content of the liquid nicotine formulation is less than or equal to approximately 9, more preferably less than or equal to approximately 8. The weight percent of water content in the liquid nicotine formulation may be less than or equal to approximately 7 times the combined weight percent of glycerin and propylene glycol content in the liquid nicotine formulation. In other words, the ratio of the weight percent of water content to the combined weight percent of glycerin and propylene glycol content of the liquid nicotine formulation may be less than or equal to approximately 7. Preferably, the weight percent water content of the liquid nicotine formulation is between approximately 0.8 times and approximately 9 times the combined weight percent glycerin and propylene glycol of the liquid nicotine formulation. For example, QZQ / nn / Lznz / e / YiAi The weight percent of water content of the liquid nicotine formulation may be between approximately 0.8 times and approximately 8 times the combined weight percent of glycerin and propylene glycol content of the liquid nicotine formulation or between approximately 0.8 and approximately 7 times the combined weight percent of glycerin and propylene glycol content of the liquid nicotine formulation. Ideally, the weight percent of water content in the liquid nicotine formulation is between approximately 1.5 times and approximately 9 times the combined weight percent of glycerin and propylene glycol in the liquid nicotine formulation. For example, the weight percent of water content in the liquid nicotine formulation may be between approximately 1.5 times and approximately 8 times the combined weight percent of glycerin and propylene glycol in the liquid nicotine formulation, or between approximately 1.5 and approximately 7 times the combined weight percent of glycerin and propylene glycol in the liquid nicotine formulation. The weight percent of water content in the liquid nicotine formulation may be between approximately 2 times and approximately 9 times the combined weight percent of glycerin and propylene glycol content in the liquid nicotine formulation. For example, the weight percent of water content in the liquid nicotine formulation may be between approximately 2 times and approximately 8 times the combined weight percent of glycerin and propylene glycol content in the liquid nicotine formulation, or between approximately 2 times and approximately 7 times the combined weight percent of glycerin and propylene glycol content in the liquid nicotine formulation. The weight percent of water content in the liquid nicotine formulation can be between approximately 3 times and approximately 9 times the combined weight percent of glycerin and propylene glycol content in the liquid nicotine formulation. For example, the weight percent of water content in the liquid nicotine formulation can be between approximately 3 times and approximately 8 times the combined weight percent of glycerin and propylene glycol content in the liquid nicotine formulation, or between QZQ / nn / Lznz / e / YiAi approximately 3 times and approximately 7 times the combined weight percent of the glycerin and propylene glycol content of the liquid nicotine formulation. The weight percent of water content in the liquid nicotine formulation may be between approximately 4 times and approximately 9 times the combined weight percent of glycerin and propylene glycol content in the liquid nicotine formulation. For example, the weight percent of water content in the liquid nicotine formulation may be between approximately 4 times and approximately 8 times the combined weight percent of glycerin and propylene glycol content in the liquid nicotine formulation, or between approximately 4 times and approximately 7 times the combined weight percent of glycerin and propylene glycol content in the liquid nicotine formulation. The weight percent of water content in the liquid nicotine formulation may be between approximately 5 times and approximately 9 times the combined weight percent of glycerin and propylene glycol content in the liquid nicotine formulation. For example, the weight percent of water content in the liquid nicotine formulation may be between approximately 5 times and approximately 8 times the combined weight percent of glycerin and propylene glycol content in the liquid nicotine formulation, or between approximately 5 times and approximately 7 times the combined weight percent of glycerin and propylene glycol content in the liquid nicotine formulation. Preferably, the liquid nicotine formulation comprises one or more water-immiscible solvents. As used herein with reference to 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. 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 Publications, Paris, https: / / doi.org / 10.1787 / 9789264069589-en. In a stepwise procedure, the following are added: 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 graduated cylinder with a glass stopper. However, when the substance is an acid, the sample is added to the distilled water in the first stage. 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 for the 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 then 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. azQ / nn / Lznz / e / YiAi Approximate solubility (mg / ml) in which 0.1 g of 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 One or more water-immiscible solvents can advantageously help to dissolve and stabilize the non-polar components of the liquid nicotine formulation. The addition of one or more 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 the size of the aerosol particles or droplets when inhaled by a user as a result of water adsorption in the respiratory tract. Preferably, the liquid nicotine formulation comprises water and one or more water-immiscible solvents. Preferably, the liquid nicotine formulation comprises water, one or more water-miscible solvents, and one or more water-immiscible solvents. Preferably, the liquid nicotine formulation comprises water, one or more water-miscible polyhydric alcohols, and one or more water-immiscible solvents. When used in an aerosol-generating system, the liquid nicotine formulation produces an aerosol comprising dual-phase particles or droplets consisting of a water-miscible phase and a water-immiscible phase. This can advantageously reduce nicotine adsorption in the upper respiratory tract and enhance 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 water-miscible phase by the water-immiscible phase. This is thought to reduce nicotine evaporation and adsorption in the upper respiratory tract. Preferably, the liquid nicotine formulation has a water-immiscible solvent content greater than or equal to approximately 1 percent by weight. More preferably, the liquid nicotine formulation has a water-immiscible solvent content greater than or equal to approximately 2 percent by weight. For example, the liquid nicotine formulation may have a water-immiscible solvent content greater than or equal to approximately 4 percent by weight, greater than or equal to approximately 6 percent by weight, or greater than or equal to approximately 8 percent by weight. The liquid nicotine formulation may have a water-immiscible solvent content less than or equal to approximately 40 percent by weight. Preferably, the liquid nicotine formulation has a water-immiscible solvent content of approximately 35 percent by weight or less. More preferably, the liquid nicotine formulation has a water-immiscible solvent content of approximately 30 percent by weight or less. For example, the liquid nicotine formulation may have a water-immiscible 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. QZQ / nn / Lznz / e / YiAi The liquid nicotine formulation may have a water-immiscible solvent content of between approximately 1 percent by weight and approximately 40 percent by weight. Preferably, the liquid nicotine formulation has a water-immiscible solvent content of between approximately 1 percent by weight and approximately 35 percent by weight. For example, the liquid nicotine formulation may have a water-immiscible solvent content of between approximately 1 percent by weight and approximately 30 percent by weight, between approximately 1 percent by weight and approximately 25 percent by weight, between approximately 1 percent by weight and approximately 20 percent by weight, or between approximately 1 percent by weight and approximately 15 percent by weight. Liquid nicotine formulations may have a water-immiscible solvent content of between approximately 2 percent by weight and approximately 40 percent by weight. Preferably, liquid nicotine formulations have a water-immiscible solvent content of between approximately 2 percent by weight and approximately 35 percent by weight. For example, liquid nicotine formulations may have a water-immiscible solvent content of between approximately 2 percent by weight and approximately 30 percent by weight, 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. Liquid nicotine formulations may have a water-immiscible solvent content of between approximately 4 percent by weight and approximately 40 percent by weight, or between approximately 4 percent by weight and approximately 35 percent by weight. For example, liquid nicotine formulations may have a water-immiscible solvent content of between approximately 4 percent by weight and approximately 30 percent by weight, 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. QZQ / nn / Lznz / e / YiAi Liquid nicotine formulations may have a water-immiscible solvent content of between approximately 6 percent by weight and approximately 40 percent by weight, or between approximately 6 percent by weight and approximately 35 percent by weight. For example, liquid nicotine formulations may have a water-immiscible solvent content of between approximately 6 percent by weight and approximately 30 percent by weight, between approximately 6 percent by weight and approximately 25 percent by weight, between approximately 6 percent by weight and approximately 20 percent by weight, or between approximately 6 percent by weight and approximately 15 percent by weight. Liquid nicotine formulations may have a water-immiscible solvent content of between approximately 8 percent by weight and approximately 40 percent by weight, or between approximately 8 percent by weight and approximately 35 percent by weight. For example, liquid nicotine formulations may have a water-immiscible solvent content of between approximately 8 percent by weight and approximately 30 percent by weight, between approximately 8 percent by weight and approximately 25 percent by weight, between approximately 8 percent by weight and approximately 20 percent by weight, or between approximately 8 percent by weight and approximately 15 percent by weight. Preferably, the one or more water-immiscible solvents comprise one or more solvents that are partially soluble in water. As used herein with reference to the invention, the term “partially water-soluble 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. One or more partially water-soluble solvents may have a maximum carbon chain length less than or equal to 12. For example, one or more partially water-soluble solvents may have a maximum carbon chain length less than or equal to 10. Suitable partially water-soluble solvents include, but are not limited to, polysorbate 80, triacetin, and triethyl citrate. azQ / nn / Lznz / e / YiAi Preferably, the one or more water-immiscible solvents comprise one or more water-insoluble solvents. As used herein with reference to the invention, the term “water-insoluble 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. One or more water-insoluble solvents may have a maximum carbon chain length less than or equal to 30. For example, one or more water-insoluble 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 solvents include, but are not limited to, oleic acid and MIGLYOL® (mixture of decanoyl and octanoyl glycerides). Preferably, the one or more water-immiscible solvents comprise one or more partially water-soluble solvents and one or more water-insoluble solvents. 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. In embodiments where the liquid nicotine formulation comprises water and one or more water-miscible solvents, the one or more nicotine salts can be advantageously dissolved and stabilized in the water and one or more water-miscible solvents. In embodiments where the liquid nicotine formulation comprises water, one or more water-miscible solvents, and one or more water-immiscible solvents, this can advantageously reduce nicotine adsorption in the upper respiratory tract and improve pulmonary nicotine delivery and retention, as discussed above. azQ / nn / Lznz / e / YiAi 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, melic 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. Ideally, liquid nicotine formulations have a water-soluble organic acid content of between approximately 3 percent and approximately 8 percent by weight. For example, liquid nicotine formulations may have a water-soluble organic acid content of between approximately 2 percent and approximately 6 percent by weight. 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 that has a Qza / nn / Lznz / e / YiAi caffeine content 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. 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 can 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 cations. 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. In accordance with the invention, a cartridge is also provided for use in an aerosol generating system, the cartridge containing a liquid nicotine formulation in accordance with the invention. The cartridge may comprise an atomizer configured to generate an aerosol from the liquid nicotine formulation. azQ / nn / Lznz / e / YiAi 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. In cartridge models that include a heated atomizer, the heating of the liquid nicotine formulation by the atomizer during use increases its temperature. This can reduce the viscosity of the liquid nicotine formulation and facilitate the generation of an inhalable aerosol with a small particle or droplet size. This can advantageously improve nicotine delivery and retention in the lungs. 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. 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. Preferably, the atomizer is 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. In models where the cartridge includes a non-thermal atomizer, the temperature of the liquid nicotine formulation does not increase significantly during use. QZQ / nn / Lznz / e / YiAi Consequently, it is particularly advantageous in such configurations that the liquid nicotine formulation has a viscosity at 20 °C of approximately 20 mPas or less. The cartridge may 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. According to 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 may 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. Preferably, the atomizer is a non-thermal atomizer. The aerosol generating system may 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. 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. QZQ / nn / Lznz / e / YiAi 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 relate, where appropriate, to the cartridge of the invention and the aerosol generating system of the invention. Similarly, the features described above in relation to the cartridge of the invention may also relate, 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 and accompanying drawings, in which: Figures 1A and 1B show the aerodynamic size distribution of aerosols generated from a liquid nicotine composition according to the invention by using four aerosol generating systems comprising non-thermal atomizers. azQ / nn / Lznz / e / YiAi Examples Four liquid nicotine formulations were prepared in accordance with the invention (Examples A, B, C, and D) having the viscosities and compositions shown in Table 2. For comparison, a liquid formulation not in accordance with the invention (Example E) was also prepared having the viscosity and composition shown in Table 2. QZQ / nn / Lznz / e / YiAi Example ABCDE Viscosity (mPa s) 2 4 6 9 29 Nicotine (% by weight) 2.7 2.7 2.7 2.7 0 Water (% by weight) 80 60 60 40 20 Vegetable glycerin (% by weight) polyhydric alcohol miscible in water 8.7 25 25 45 40 Propylene glycol (% by weight) 1.5 4.2 4.2 4.2 40 Triacetin (% by weight) solvent partially soluble in water 0.9 2 2 2 0 Triethyl citrate (% by weight) 2 2 10 2 0 Lactic acid (% by weight) organic acid soluble in water 4.3 4.3 4.3 4.3 0 Table 2 Aerosols were generated from the liquid nicotine composition according to the invention of Example A by using the four aerosol generating systems comprising the non-thermal atomizers shown in Table 3. The aerodynamic size distributions of the aerosols were measured using a TSI Incorporated Model 3321 Aerodynamic Part Sizer® (APS™) spectrometer. The results are shown in Figures 1A and 1B. Example Non-thermal aerosol generating system Example A1 Impact jet nebulizer (nozzle opening: 10 microns; driving force: 51 N) Example A2 OMRON Healthcare MicroAIR U100 passive mesh nebulizer (driven by 50 Vpp at 177 kHz with 2 Hz modulation; mesh orifice diameter: approximately 4 microns; distance between mesh orifices approximately 60 microns) Example A3 Air Wick® Essential Mist Diffuser active mesh nebulizer (120 - 180 kHz; mesh orifice diameter: 4-8 microns) Example A4 Surface acoustic wave (SAW) device (dual motor operation with each side driven by 600 mVpp at 42.122 MHz with 500 Hz modulation) QZQ / nn / Lznz / e / YiAi Table 3 Figure 1A shows the differential mass concentration (dM) versus the aerodynamic diameter (APS diameter) of the aerosols and Figure 1B shows the differential number of particles (dN) concentration versus the aerodynamic diameter (APS diameter) of the aerosols. As shown in Figures 1A and 1B, the use of the liquid nicotine composition according to the invention of Example A in the four aerosol generating systems advantageously generates aerosols exhibiting a small droplet size.

Claims

1. A liquid nicotine formulation for use in an aerosol generating system, the liquid nicotine formulation comprising glycerin and having a viscosity at 20°C less than or equal to approximately 20 mPa-s, wherein the liquid nicotine formulation is a substantially caffeine-free liquid nicotine formulation and wherein the liquid nicotine formulation has a glycerin content greater than or equal to approximately 6 percent by weight.

2. A liquid nicotine formulation according to claim 1 having a viscosity at 20 °C less than or equal to approximately 12 mPa s.

3. A liquid nicotine formulation according to claim 1 or 2 having a viscosity at 20 °C greater than or equal to approximately 1 mPa s.

4. A liquid nicotine formulation according to any of claims 1 to 3 comprising water, wherein the liquid nicotine formulation has a water content greater than or equal to approximately 30 percent by weight.

5. A liquid nicotine formulation according to claim 4, wherein the weight percent of the water content of the liquid nicotine formulation is at least approximately 0.8 times the weight percent of the water-miscible solvent content of the liquid nicotine formulation.

6. A liquid nicotine formulation according to any of claims 3 to 5, comprising one or more water-immiscible solvents having a water solubility at 20°C less than or equal to approximately 100 mg / ml, wherein the liquid nicotine formulation has a water-immiscible solvent content greater than or equal to approximately 2 percent by weight.

7. A liquid nicotine formulation according to claim 6, wherein the one or more water-immiscible solvents comprise one or more partially water-soluble solvents having a water solubility at 20°C of between approximately 20 mg / ml and approximately 100 mg / ml. QZQ / nn / Lznz / e / YiAi 8. A liquid nicotine formulation according to claim 7, wherein the one or more water-immiscible solvents comprise one or more water-insoluble solvents having a water solubility at 20 °C less than or equal to approximately 5 mg / ml.

9. A liquid nicotine formulation according to any of claims 3 to 8, 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.

10. A cartridge for use in an aerosol generating system, the cartridge containing a liquid nicotine formulation in accordance with any of claims 1 to 9.

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

12. An aerosol generating system comprising: a liquid nicotine formulation according to any of claims 1 to 9; and an atomizer configured to generate an aerosol from the liquid nicotine formulation.

13. A cartridge according to claim 11 or an aerosol generating system according to claim 12, wherein the atomizer is a non-thermal atomizer.

14. A cartridge according to claim 11 or an aerosol generating system according to claim 12, wherein the atomizer is a thermal atomizer comprising a heater and a liquid delivery element configured to deliver the liquid nicotine formulation to the heater.