CN115166070A

CN115166070A - Method for testing nicotine content in tobacco tar or aerosol and method for preparing electronic cigarette tobacco tar

Info

Publication number: CN115166070A
Application number: CN202210680606.9A
Authority: CN
Inventors: 邓杰; 苏凌铖; 杨何辉; 钟家鸣
Original assignee: Shenzhen Satwa Biotechnology Co ltd
Current assignee: Shenzhen Satwa Biotechnology Co ltd
Priority date: 2022-06-16
Filing date: 2022-06-16
Publication date: 2022-10-11

Abstract

The invention relates to a method for testing nicotine content in tobacco tar or aerosol and a method for preparing electronic cigarette tobacco tar. The method for testing the nicotine content in the tobacco tar or the aerosol comprises the following steps: mixing a sample to be detected with water, and then adding an organic solvent immiscible with water for extraction to obtain an aqueous phase solution and an organic phase solution; the sample to be detected is tobacco tar or aerosol after smoking the tobacco tar; testing the content of the combined nicotine in the aqueous phase solution by using liquid chromatography; the organic phase solution was tested for free nicotine content by gas chromatography. The testing method has high detection precision.

Description

Method for testing nicotine content in tobacco tar or aerosol and method for preparing electronic cigarette tobacco tar

Technical Field

The invention relates to the field of electronic cigarettes, in particular to a method for testing nicotine content in tobacco tar or aerosol and a method for preparing electronic cigarette tobacco tar.

Background

The e-cigarette can provide a user with the satisfaction of a puff similar to that of traditional burning tobacco. The electronic cigarette comprises an appliance and tobacco tar, wherein the appliance is used for atomizing the tobacco tar to generate aerosol to be supplied to a user for smoking. The e-liquid includes nicotine to provide a satisfaction similar to smoking conventional tobacco. Since the nicotine structure contains two N-containing groups, pyridine and pyrrole, there are 3 morphologies at different pH conditions: the gemini proton state, the simple proton state and the free state, wherein the gemini proton state and the simple proton state are collectively called as a combined state, which is shown as follows:

when the content of free nicotine in the tobacco tar is too high, the user inhales the atomized aerosol to generate strong throat feeling, so that the user is easy to choke. Because nicotine is an alkaline substance, the organic acid is added in the tobacco tar, the reaction of nicotine and organic acid can be promoted to generate salt, so that the content of free nicotine in the tobacco tar is reduced, and simultaneously, because the process is in dynamic balance, the mixing ratio of nicotine and organic acid is an important factor influencing the taste of aerosol.

At present, the existing method tests the content of free nicotine and combined nicotine in electronic tobacco tar, but because the precision of the detection result is low, when the tobacco tar is prepared according to the tested result, the taste difference of users during smoking is large, and the consistency is poor.

Disclosure of Invention

Based on this, it is necessary to provide a test method for detecting the nicotine content in tobacco tar or aerosol with high accuracy.

In addition, a method for preparing the electronic cigarette tobacco tar is also needed.

A method for testing the nicotine content in tobacco tar or aerosol comprises the following steps:

mixing a sample to be detected with water, and then adding an organic solvent immiscible with water for extraction to obtain an aqueous phase solution and an organic phase solution; the sample to be detected is tobacco tar or aerosol after the tobacco tar is sucked;

measuring the content of bound nicotine in the aqueous solution by liquid chromatography;

the content of free nicotine in the organic phase solution was tested by gas chromatography.

In one embodiment, the organic solvent is selected from at least one of dichloromethane, chloroform and dichlorobenzene; and/or the presence of a catalyst in the reaction mixture,

the water is deionized water, high-purity water or ultrapure water; and/or the like, and/or,

the volume ratio of the organic solvent to the water is 1 (1-200); and/or the presence of a catalyst in the reaction mixture,

in the step of adding the organic solvent immiscible with water for extraction, shaking for extraction for 30-60 min.

In one embodiment, the sample to be detected is tobacco tar, and the mass-to-volume ratio of the sample to be detected to water is 1g (100 mL-200 mL).

In one embodiment, the sample to be tested is aerosol after smoking tobacco, and the sample to be tested is obtained by the following steps:

the tobacco tar is placed on an electronic cigarette appliance, smoking is carried out on smoking equipment, and 5-30 mouthes of aerosol are collected.

In one embodiment, the parameters of the pumping are: the volume of aerosol sucked by each port is 55mL, the suction time of each port is 3s, and the process is stopped for 27s; and/or the presence of a catalyst in the reaction mixture,

the volume ratio of the tobacco tar to the water is (0.5-2): 10.

In one embodiment, the sample to be tested further contains an organic acid, and in the step of testing the content of the bound nicotine in the aqueous phase solution by liquid chromatography, the content of the bound organic acid in the aqueous phase solution is tested simultaneously;

in the step of testing the content of free nicotine in the organic phase solution by gas chromatography, the content of free organic acid in the organic phase solution is simultaneously tested.

In one embodiment, the organic acid comprises at least one of benzoic acid, tartaric acid, citric acid, succinic acid, fumaric acid, and malic acid.

In one embodiment, in the step of testing the content of the combined nicotine in the aqueous phase solution by liquid chromatography, an external standard method is adopted; and/or the like, and/or,

in the step of testing the content of free nicotine in the organic phase solution by using the gas chromatography, an external standard method is adopted.

In one embodiment, the procedure parameters of the liquid chromatograph used in the liquid chromatography for measuring the content of the bound nicotine in the aqueous solution include: the mobile phase A is acetonitrile, and the mobile phase B is phosphoric acid aqueous solution with pH less than 3; gradient program: 0-2.5min, 100% of mobile phase B;3.0 min-5.0 min, the mobile phase B with the volume percentage of 90 percent and the mobile phase A with the volume percentage of 10 percent; 7.0min to 11.0min, wherein the volume percentage of the mobile phase B is 70 percent and the volume percentage of the mobile phase A is 30 percent; 11.5 min-16.0 min,100% mobile phase B; and/or the presence of a catalyst in the reaction mixture,

in the process of testing the content of free nicotine in the organic phase solution by using the gas chromatography, the program parameters of the gas chromatograph comprise: sample inlet temperature: 220 ℃; detector temperature: 220 ℃; temperature programming: the initial temperature is 100 ℃, the temperature is kept for 0min, the temperature is increased from 100 ℃ to 230 ℃ at the heating rate of 20 ℃/min, and the temperature is kept for 5min.

In one embodiment, the method further comprises the following steps:

providing a validation tobacco tar, wherein the validation tobacco tar contains a known amount of combined nicotine and/or free nicotine;

adding water into the verified tobacco tar for mixing, and then extracting by using the organic solvent to obtain a verified water phase solution and a verified organic phase solution;

measuring the amount of bound nicotine in said validated aqueous solution by liquid chromatography and comparing it to a theoretical amount of bound nicotine;

the content of free nicotine in the validated organic phase solution was tested by gas chromatography and compared to the theoretical content of free nicotine.

A method for preparing electronic cigarette tobacco tar comprises the following steps:

preparing a plurality of standard tobacco tar, wherein the molar ratio of nicotine to organic acid used in the process of preparing the plurality of standard tobacco tar is different;

testing the free nicotine and the combined nicotine content in a plurality of standard tobacco oils by the testing method;

calculating the percentage of bound nicotine in each of said standard tobacco oils based on the amount of free nicotine and bound nicotine tested, based on the total nicotine content;

the minimum molar ratio of nicotine and organic acid corresponding to the preset value of the percentage of the combined nicotine in the total nicotine content is used as the preset molar ratio;

mixing nicotine and organic acid according to a preset molar ratio to prepare the electronic cigarette tobacco tar.

In one embodiment, the organic acid is benzoic acid, and the preset value is 88-93%; alternatively, the first and second electrodes may be,

the organic acid is succinic acid, and the preset value is 96.5-98.5%.

According to the method for testing the nicotine content in the tobacco tar or the aerosol, water is firstly added into a sample to be tested, so that the combined nicotine, the free nicotine and the like in the tobacco tar are dissolved in the water; then adding organic solvent, fully stirring and oscillating, and because of the principle of similar intermiscibility, free nicotine is more soluble in organic reagent, and combined nicotine is more soluble in aqueous phase solution. The content of the combined nicotine in the aqueous phase solution and the content of the free nicotine in the organic phase solution are respectively tested by the liquid chromatography and the gas chromatography, so that the test accuracy is improved.

Drawings

FIG. 1 is a schematic view of one embodiment of a collection device used in a test sample preparation process;

FIG. 2 is a graph showing the results of the test in example 2;

FIG. 3 is a graph showing the results of the test in example 3 by liquid chromatography;

FIG. 4 is a graph showing the results of gas chromatography testing in example 3;

FIG. 5 is a graph showing the results of the test in example 4;

FIG. 6 is a graph showing the results of the test in example 5;

FIG. 7 is a graph showing the results of the test in example 6;

FIG. 8 is a graph showing the results of the test in example 7;

FIG. 9 is a graph showing the results of the test in example 8;

FIG. 10 is a graph showing the results of the test in example 9;

FIG. 11 is a graph showing the results of the test in example 10.

Detailed Description

In order that the invention may be more fully understood, reference will now be made to the following description taken in conjunction with the accompanying drawings. Preferred embodiments of the present invention are given in the detailed description. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

The addition of nicotine to the electronic cigarette tobacco tar can provide satisfaction similar to smoking traditional tobacco. Nicotine dissociation constant pK _a1 ＝3.12、pK _a2 =8.02, when the solution pH is more than or equal to 8, the solution exists mainly in free nicotine form; when the pH is between 5 and 7, the nicotine exists mainly in a single molecular nicotine form; when the pH value of the solution is less than or equal to 3, the nicotine mainly exists in a biprotonic nicotine form. When the content of free nicotine in tobacco tar is too high, the user inhales the tobacco tarThe atomized aerosol generates strong throat-hitting feeling, even bitter, spicy and the like to stimulate the throat of a user, so that the user is easy to choke. A method for measuring the content of free nicotine and nicotine salt in tobacco tar by using a gas phase method is disclosed in the conventional art. The data obtained by the method is low in precision, so that the tobacco tar preparation efficiency is low, and the taste difference of aerosol generated by atomization is obvious.

Based on the method, the invention provides a test method capable of improving the precision of detecting the nicotine content in the tobacco tar.

Specifically, the method for testing the nicotine content in the tobacco tar or the aerogel of one embodiment comprises the following steps:

step S110: firstly, mixing a sample to be detected with water, and then adding an organic solvent immiscible with water for extraction to obtain an aqueous phase solution and an organic phase solution.

In some embodiments, the sample to be tested is tobacco tar. The mass volume ratio of the sample to be detected to water is 1g (100 mL-200 mL). For example, the mass-to-volume ratio of the sample to be measured to water is 1g.

Specifically, the water is deionized water, high purity water or ultrapure water. Since the change of the pH of the solution has a great influence on the testing of the free nicotine in the tobacco tar sample, in this embodiment, the water used is deionized water, high purity water or ultrapure water. Preferably, the water is ultrapure water.

Specifically, the organic solvent is at least one selected from the group consisting of dichloromethane, chloroform and dichlorobenzene. The organic solvent is immiscible with water, and water is added into a sample to be detected firstly, so that the combined nicotine, the free nicotine and the like in the tobacco tar are dissolved in the water; then adding organic solvent, fully stirring and oscillating, wherein free nicotine is more soluble in the organic solvent and combined nicotine is more soluble in water due to the similar phase-dissolving principle, and separating to obtain water phase solution and organic phase solution. The content of the combined nicotine in the aqueous phase solution and the content of the free nicotine in the organic phase solution are respectively tested by the liquid chromatography and the gas chromatography, so that the test accuracy is improved. It is understood that the organic solvent is not limited thereto, and may be other solvents which are immiscible with water and can dissolve the free nicotine.

Furthermore, the volume ratio of the organic solvent to the water is 1 (1-200). In a specific example, the volume ratio of organic solvent to water is 1, 1.

In one embodiment, in the step of mixing the sample to be measured with water, the sample to be measured is shaken for 5min to 20min so as to fully mix the sample to be measured with water. And (4) carrying out vortex oscillation or stirring uniformly, so that nicotine, nicotine salt and the like in the tobacco tar are dissolved in water.

In one embodiment, in the step of adding the water-immiscible organic solvent for extraction, shaking for 30min to 60min is performed, so that the organic solvent can sufficiently extract the free nicotine in the aqueous phase solution.

In other embodiments, the sample to be tested is an aerosol after smoking tobacco.

Specifically, the sample to be tested is obtained by the following steps:

the tobacco tar is placed on an electronic smoking device, smoking is carried out on smoking equipment, and 5-30-mouth aerosol is collected by a collecting device.

In one specific example, the parameters of the suction are: the aerosol volume per puff was 55mL, the duration of each puff was 3s, and the pause was 27s.

In one embodiment, the ratio of the volume of tobacco tar used in obtaining the sample to be tested to the volume of water used in mixing the sample to be tested with water is (0.5-2): 10. For example, the volume ratio of tobacco tar to water is 0.5.

Further, after the suction is finished, the stopping time is 5min, so that the aerosol is fully absorbed by the collecting device.

In a specific example, referring to fig. 1, the collecting device includes an adsorption layer 1, an adsorption layer 2 and an adsorption layer 3, the adsorption layer 1 is a coconut shell activated carbon layer, the adsorption layer 2 is a cotton cloth activated carbon layer, and the adsorption layer 3 is a cambridge filter. And assembling the adsorption layers in the collecting device, sequentially connecting a smoking machine and an electronic cigarette appliance to ensure the sealing property in the aerosol collecting process, pausing for 5min after the smoking is finished, and allowing the aerosol to be completely absorbed by the adsorption layers in the aerosol collector. The adsorption layer 1, the adsorption layer 2 and the adsorption layer 3 are folded into a strip shape towards the aerosol surface in sequence and transferred into a centrifuge tube.

Step S120: the content of bound nicotine in the aqueous solution was measured by liquid chromatography.

Specifically, in the step of measuring the content of the bound nicotine in the aqueous solution by liquid chromatography, an external standard method is adopted.

In one specific example, the set parameters of the liquid chromatograph used during the liquid chromatography test include: the mobile phase A is acetonitrile, and the mobile phase B is phosphoric acid aqueous solution with pH less than 3; gradient program: 0-2.5min, 100% of mobile phase B;3.0 min-5.0 min, the mobile phase B with the volume percentage of 90 percent and the mobile phase A with the volume percentage of 10 percent; 7.0min to 11.0min, wherein the volume percentage of the mobile phase B is 70 percent and the volume percentage of the mobile phase A is 30 percent; 11.5-16.0 min,100% mobile phase B. In a specific example, the mobile phase B may be an aqueous phosphoric acid solution with pH of 2.8, 2.5, 2.2, 2. The mobile phase can solve the problem of trailing of the main peak of the measured substance in the test process.

In addition, the program parameters of the liquid chromatograph further include a flow rate, a sample introduction amount, and the like, and in a specific example, the program parameters of the liquid chromatograph are as follows:

the instrument model is as follows: waters Hclass band ultraviolet detector; and (3) chromatographic column: shim-pack Scepter C8-120,1.9um 2.1x100mm; column temperature: 30 ℃; flow rate: 0.2mL/min; sample introduction amount: 1.0 μ L; the mobile phase A is acetonitrile; the mobile phase B is phosphoric acid water solution with pH less than 3; gradient program: 0-2.5min, 100% of mobile phase B; 3.0-5.0 min, mobile phase B with the volume percentage of 90 percent and mobile phase A with the volume percentage of 10 percent; 7.0-11.0 min,70% mobile phase B +30% mobile phase A, 11.5-16.0 min,100% mobile phase B.

In some embodiments, the sample to be tested further contains an organic acid, and in the step of testing the content of the bound nicotine in the aqueous solution by liquid chromatography, the content of the bound organic acid in the aqueous solution can also be tested simultaneously, and the bound nicotine and the bound organic acid do not need to be tested separately, so that the testing efficiency is improved, and the testing accuracy is improved. The test organic acid can be used for testing whether the program parameter setting of the equipment is accurate, if only nicotine is used for testing, the test organic acid is too single and persuasive; in addition, the content of the organic acid can be detected, so that the contents of the combined organic acid and the free organic acid can be more conveniently known, for example, when 1g of the organic acid is added, the combined state is 0.7 g and the free state is 0.3 g; when 2 g of organic acid is put in the reactor, the combined state is 1.2 g and the free state is 0.8 g, and the optimal proportion is selected according to the change of the content of different organic acids.

Specifically, the organic acid includes at least one of benzoic acid, tartaric acid, citric acid, succinic acid, fumaric acid, and malic acid. It is understood that the organic acid is not limited thereto, and may be an organic acid commonly used in the electronic cigarette smoke in the art.

Further, before the step of testing the content of the bound nicotine in the aqueous phase solution by using the liquid chromatography, the method also comprises a step of passing the aqueous phase solution through a membrane, specifically, passing the aqueous phase solution through a filtering membrane to filter out impurities or macromolecular substances, so as to prevent the impurities or the macromolecular substances from influencing the precision of the liquid chromatograph test.

Step S130: the organic phase solution was tested for free nicotine content by gas chromatography.

In some embodiments, the sample to be tested further comprises an organic acid, and in the step of testing the content of the free nicotine in the organic phase solution by gas chromatography, the content of the free organic acid in the organic phase solution is also tested.

In one specific example, the set parameters of the gas chromatograph used during the gas chromatography test include: sample inlet temperature: 220 ℃; detector temperature: 220 ℃; temperature programming: the initial temperature is 100 ℃, the temperature is kept for 0min, the temperature is increased from 100 ℃ to 230 ℃ at the heating rate of 20 ℃/min, and the temperature is kept for 5min. Further, the program parameters of the gas chromatograph further include a sample introduction amount, a carrier gas, and the like, and in a specific example, the program parameters of the gas chromatograph are as follows:

the instrument model is as follows: agilent8890 with FID detector; a chromatographic column: DB-WAX (250 ℃ C.: 30 m. Times.0.25 mm. Times.0.25 μm); sample inlet temperature: 220 ℃; detector temperature: 220 ℃; sample introduction amount: 1.0 μ L temperature program: maintaining at 100 deg.C for 0min; heating from 100 deg.C to 230 deg.C at a rate of 20 deg.C/min, and maintaining for 5min; carrier gas: nitrogen, 1.5mL/min; sample introduction amount: 0.2 μ L, split injection, split ratio 20.

Further, before the step of testing the content of the free nicotine in the organic phase solution by using the gas chromatography, the method also comprises the step of passing the organic phase solution through a membrane, in particular, passing the organic phase solution through a filter membrane.

Step S140: the total nicotine content is calculated from the combined and free nicotine content.

Specifically, the total content of nicotine = the content of bound nicotine + the content of free nicotine.

In some embodiments, the method further comprises a step of verifying the parameters set by the device, so as to ensure that the error of the device itself and the error of the test result are large, thereby improving the accuracy of the device test.

Specifically, the step of verifying comprises:

providing a verification tobacco tar, wherein the verification tobacco tar contains known amount of combined nicotine and/or free nicotine;

adding water into the verified tobacco tar for mixing, and then extracting by using an organic solvent to obtain a verified water phase solution and a verified organic phase solution;

testing the content of the identified combined nicotine in the aqueous solution by using a liquid chromatography method, and comparing the content with the theoretical content of the combined nicotine;

the content of free nicotine in the organic phase solution verified by gas chromatography was measured and compared with the theoretical content of free nicotine.

Specifically, if the ratio of the measured content of the bound nicotine to the theoretical content of the bound nicotine is greater than 97%, and the ratio of the measured content of the free nicotine to the theoretical content of the free nicotine is greater than 97%, it indicates that the error of the used equipment is small, and the accuracy of the result obtained by the test is high. Meanwhile, the set parameters of the testing instrument can be used for accurately or highly precisely detecting the nicotine content or the organic acid content in the prepared tobacco tar.

The method for testing the nicotine content in the tobacco tar or the aerosol at least has the following advantages:

(1) According to the method for testing the nicotine content in the tobacco tar or the aerosol, water is firstly added into a sample to be tested, so that the combined nicotine, the free nicotine and the like in the tobacco tar are dissolved in the water; then adding organic solvent, fully stirring and oscillating, wherein free nicotine is more soluble in organic reagent and combined nicotine is more soluble in aqueous phase solution due to the principle of similar intermiscibility. The content of the combined nicotine in the aqueous phase solution and the content of the free nicotine in the organic phase solution are respectively tested by the liquid chromatography and the gas chromatography, so that the test accuracy is improved.

(2) The method for testing the nicotine content in the tobacco tar or the aerosol can also be used for testing the content of the organic acid at the same time, and the nicotine salt content in the tobacco tar is prepared by adjusting the total nicotine amount or the total organic acid amount added in the tobacco tar, so that the optimal proportioning relation can be quickly obtained, and the tobacco tar preparation efficiency is improved.

(3) The sample tested by the testing method has high recovery rate, the tested total nicotine recovery rate is more than 97 percent, the testing precision is high, and the error is small.

The invention also provides a method for preparing the electronic cigarette tobacco tar of the embodiment, which comprises the following steps:

step S210: preparing a plurality of standard tobacco oils, wherein the molar ratio of nicotine to organic acid used in the process of preparing the plurality of standard tobacco oils is different.

Specifically, the molar ratio of nicotine to organic acid can be adjusted according to the theoretical molar ratio used for complete reaction of nicotine and organic acid. For example, in one specific example, the organic acid is benzoic acid, the benzoic acid is a monobasic acid, 1mol of benzoic acid can form 1mol of nicotinic benzoate salt with 1mol of nicotine, and the reaction of the nicotinic benzoate salt formation is shown below.

Thus, the molar ratio of nicotine to organic acid used in formulating a plurality of standard tobacco products can be set between 1.

In another specific example, the organic acid is succinic acid, and since succinic acid is dicarboxylic acid, the succinate in the tobacco tar can exist in two states, one state is that 1mol of succinic acid and 1mol of nicotine form 1mol of nicotine succinate (main), and the other state is that 1mol of succinic acid and 2mol of nicotine form 1mol of nicotine succinate (secondary), and the salt formation reaction of the two kinds of nicotine succinate is as follows:

Step S220: the content of free nicotine and bound nicotine in a number of standard tobacco products were tested.

Specifically, the content of free nicotine and bound nicotine in a plurality of standard tobacco oils is tested by the testing method of the above embodiment, which is not described herein again.

Step S230: the percentage of bound nicotine in each standard tobacco oil to the total nicotine content was calculated based on the free and bound nicotine levels tested.

Specifically, the percentage of bound nicotine as a whole nicotine content = bound nicotine content/(bound nicotine content + free nicotine content) × 100%.

Step S240: the minimum molar ratio of nicotine and organic acid corresponding to the preset value of the percentage of the nicotine in the combined state to the total nicotine content is the preset molar ratio.

In one embodiment, the organic acid is benzoic acid, and the preset value is 88% -93%.

In another embodiment, the organic acid is succinic acid, the preset value is 96.5-98.5%.

Step S250: mixing nicotine and organic acid according to a preset molar ratio to prepare the electronic cigarette tobacco tar.

According to the preparation method of the electronic cigarette tobacco tar, the plurality of standard tobacco tar are prepared firstly, then the content of free nicotine and combined nicotine in the standard tobacco tar is tested, and the percentage of the content of the combined nicotine is calculated, wherein the higher the content of the combined nicotine is, the smoother the smoking is, the throat hitting feeling is weak, and meanwhile, the satisfaction is improved. However, as the content of the organic acid is further increased, the percentage of the combined nicotine does not change much, but the increase of the content of the organic acid increases the viscosity of the tobacco tar, which is not beneficial to the flowing and atomizing of the tobacco tar, and the cost also increases correspondingly, therefore, in the embodiment, the minimum molar ratio of the nicotine and the organic acid corresponding to the preset value of the percentage of the combined nicotine in the total nicotine content is used as the preset molar ratio, and the electronic tobacco tar is prepared according to the preset molar ratio, so that on one hand, the throat hitting feeling during smoking is ensured to be weak, the satisfaction is improved, and on the other hand, the cost is reduced. In addition, the method for preparing the tobacco tar is high in efficiency, and the difference of the mouthfeel of aerosol generated by atomization is small.

In order to make the objects and advantages of the present invention more apparent, the following detailed description of the test method and its effects are taken in conjunction with the following embodiments, and it should be understood that the embodiments described herein are only for the purpose of illustrating the present invention and are not to be taken as limiting the present invention. The following examples are not specifically described, and other components except inevitable impurities are not included. The examples, which are not specifically illustrated, employ drugs and equipment, all of which are conventional in the art. The experimental procedures without specifying the specific conditions in the examples were carried out under the conventional conditions such as those described in the literature, in books, or as recommended by the manufacturer.

The test procedure parameters for the gas chromatograph and the liquid chromatograph used in the following examples are as follows:

the procedure parameters for the liquid chromatograph were as follows:

the instrument model is as follows: a Waters Hclass band uv detector; a chromatographic column: shim-pack Scepter C8-120,1.9um 2.1x100mm; column temperature: 30 ℃; flow rate: 0.2mL/min; sample introduction amount: 1.0 mu L; the mobile phase A is acetonitrile; mobile phase B, pH =2 phosphoric acid water solution; gradient program: 0-2.5min, 100% of mobile phase B; 3.0-5.0 min,90% mobile phase B +10% mobile phase A; 7.0-11.0 min,70% mobile phase B +30% mobile phase A, 11.5-16.0 min,100% mobile phase B.

The program parameters of the gas chromatograph were as follows:

Example 1

The embodiment provides a method for verifying a gas chromatograph and a liquid chromatograph used in a test process, which specifically comprises the following steps:

(1) Preparing a tobacco tar sample without nicotine and organic acid, weighing 0.1g of the tobacco tar sample, placing the tobacco tar sample in a 50mL centrifugal tube with a plug, adding 0.0245g of free nicotine, adding 10mL of ultrapure water, sealing the centrifugal tube with a cover, carrying out vortex oscillation for 5min, adding 10mL of dichloromethane, placing the mixture in an oscillator, carrying out oscillation extraction for 30min, and standing for layering to obtain an aqueous phase solution and an organic phase solution.

(2) Taking the aqueous phase solution, placing the aqueous phase solution after the membrane is passed in a liquid chromatograph, and measuring the content of the combined nicotine by a liquid phase method to be 0mg/g.

(3) Taking the organic phase solution, placing the organic phase solution after the film is filtered in a gas chromatograph, and calculating and measuring the content of the free nicotine by using an external standard method of a gas phase method to obtain 24.2mg/g.

By calculating the formula: recovery = (free nicotine content measured by gas phase method + bound nicotine content measured by liquid phase method)/free nicotine content added × 100%, recovery of 98.77% was calculated. Therefore, the error amount of the used equipment is small, and the precision of the result obtained by the test is high. Meanwhile, the program setting method of the testing instrument can be used for accurately or precisely detecting the nicotine content or the organic acid content in the prepared tobacco tar.

Example 2

The embodiment provides a method for checking a gas chromatograph and a liquid chromatograph used in a testing process, which specifically comprises the following steps:

(1) A tobacco tar sample was prepared containing a mixture of 0.01g nicotine, 0.01g benzoic acid, 0.01g tartaric acid, 0.01g citric acid, 0.01g succinic acid, 0.01g fumaric acid, 0.01g malic acid.

(2) Diluting a tobacco tar sample with an aqueous solution containing 20 mass percent of acetonitrile and 0.5 mass percent of phosphoric acid, transferring the uniformly mixed sample into a brown sample bottle, and finally placing the brown sample bottle in a liquid chromatograph for testing by using a liquid phase method. The results are shown in FIG. 2;

as can be seen from fig. 2, the nicotine, benzoic acid, tartaric acid, citric acid, succinic acid, fumaric acid, and malic acid are detected in the liquid chromatography, and the content of each substance calculated according to the external standard method is: 9.85mg/g nicotine, 9.87mg/g benzoic acid, 9.95mg/g tartaric acid, 9.75mg/g citric acid, 9.93mg/g succinic acid, 9.81mg/g fumaric acid, 9.97mg/g malic acid. Therefore, the types of the captured atomized substances are complete and accurate during detection.

Calculating the recovery rate: the recovery rate of nicotine is 98.5%, the recovery rate of benzoic acid is 98.7%, the recovery rate of tartaric acid is 99.5%, the recovery rate of citric acid is 97.5%, the recovery rate of succinic acid is 99.3%, the recovery rate of fumaric acid is 98.1% and the recovery rate of malic acid is 99.7%. It can be seen from fig. 2 that there is no tailing phenomenon, and thus the accuracy of the detection result using the liquid chromatograph is high.

It can be seen from the above embodiments that the accuracy of the test result is high by using the above apparatus and program parameters.

Example 3

In this example, a benzoic acid nicotine salt tobacco tar sample was prepared according to a molar ratio of nicotine to benzoic acid of 1, wherein the theoretical nicotine content is 30.21mg/g, and the theoretical benzoic acid content is 22.76mg/g, and the contents of nicotine and organic acid in the tobacco tar were measured by the following steps:

(1) Weighing 0.1g tobacco tar sample, placing in a 50mL centrifuge tube with plug scales, adding 10mL ultrapure water, sealing with a cover, performing vortex oscillation for 5min, adding 10mL dichloromethane, placing in an oscillator, performing oscillation extraction for 30min, standing for layering to obtain an aqueous phase solution and an organic phase solution.

(2) Taking the aqueous phase solution, placing the aqueous phase solution after the film is passed in a liquid chromatograph, and calculating the content of the combined nicotine by using an external standard method of a liquid phase method to measure 25.09mg/g and the content of the combined benzoic acid by using 19.81mg/g. The specific test results are shown in fig. 3.

(3) Taking an organic phase solution, placing the organic phase solution after the organic phase solution passes through a membrane in a gas chromatograph, and measuring the content of free nicotine and the content of free benzoic acid by using an external standard method of a gas phase method to be 5.00mg/g and 2.81mg/g respectively. The specific test results are shown in fig. 4.

The total nicotine content = the bound nicotine content measured by the liquid phase method + the free nicotine content measured by the gas phase method, and the total benzoic acid content = the bound benzoic acid content measured by the liquid phase method + the free benzoic acid content measured by the gas phase method. Through calculation, the total content of nicotine is 30.09mg/g and the total content of benzoic acid is 22.62mg/g. Nicotine recovery = tested total nicotine content/theoretical nicotine content x 100% = (30.09/30.21) × 100% =99.6%, benzoic acid recovery = (22.62/22.76) × 100% =99.4%. Therefore, the test method can achieve the expected recovery rate and has higher test accuracy.

Example 4

diluting 0.1g of tobacco tar sample with isopropanol solution containing internal standard, oscillating for 30min, extracting, testing the benzoic acid nicotine salt tobacco tar sample by using a liquid phase method, and calculating the measured bound nicotine content of 29.56mg/g and the bound benzoic acid content of 20.83mg/g by using an external standard method, wherein the specific test result is shown in fig. 5. Nicotine recovery = (29.56/30.21) × 100% =97.85%. As can be seen from fig. 5 in which the recovery rate of benzoic acid = (20.83/22.76) × 100% =91.5%, and the recovery rate is combined with the target substance detected by the liquid phase method alone, the result data indicates that the recovery rate of benzoic acid is not more than 97%, indicating that a part of free benzoic acid is not detected in the smoke sample, and therefore, the accuracy is not high when the target substance is detected by the liquid phase method alone.

Example 5

In this embodiment, a nicotine succinate salt tobacco tar sample is prepared according to a molar ratio of nicotine to succinic acid of 1.6, wherein the theoretical nicotine content is 30.07mg/g, and the theoretical succinic acid content is 35.02mg/g, and the contents of nicotine and organic acid in the tobacco tar are tested by the following steps:

respectively weighing 0.1g of each of two tobacco tar samples, placing one of the two tobacco tar samples in a 15mL centrifugal tube with a plug scale, adding 10mL of an aqueous solution containing acetonitrile and phosphoric acid, wherein the mass percentage concentration of the acetonitrile is 20%, the mass percentage concentration of the phosphoric acid is 0.5%, placing the centrifugal tube in an oscillator after being covered and sealed, oscillating and extracting for 20min, standing, transferring an extract into a brown sample bottle, finally placing the bottle in a liquid chromatograph, and calculating the content of the combined nicotine by using an external standard method of a liquid phase method to obtain the content of the combined nicotine of 29.84mg/g and the content of the combined succinic acid of 30.25mg/g. Nicotine recovery = (29.84/30.07) × 100% =99.24%; succinic acid recovery = (30.25/35.02) × 100% =86.4%. The liquid chromatography test spectrum is shown in fig. 6.

Putting the electronic cigarette oil into a 50mL centrifugal tube with a plug scale, adding 10mL ultrapure water, covering and sealing, performing vortex oscillation for 5min, adding 10mL dichloromethane, putting into an oscillator, performing oscillation extraction for 30min, standing and layering to obtain a water phase solution, putting the water phase solution after membrane filtration into a liquid chromatograph, and calculating by using an external standard method of a liquid phase method to obtain the content of the bound nicotine of 29.44mg/g and the content of the bound succinic acid of 21.78mg/g; meanwhile, taking an organic phase solution, placing the organic phase solution after the film is coated in a gas chromatograph, and measuring the content of free nicotine and the content of free succinic acid by using an external standard method of a gas phase method to be 0.34mg/g and 12.85mg/g respectively.

Calculating the total nicotine content and the total organic acid content according to a formula, wherein the total nicotine content = the combined nicotine content measured by a liquid phase method + the free nicotine content measured by a gas phase method, namely the total nicotine content =29.44+0.34=29.78mg/g, the nicotine recovery rate = (29.78/30.07) × 100% =99.04%, and the total succinic acid content = the combined succinic acid content measured by the liquid phase method + the free succinic acid content measured by the gas phase method; namely the total amount of succinic acid =21.78+12.85=34.63mg/g, and the recovery rate of succinic acid = (34.63/35.02) × 100% =98.9%.

By combining the recovery rate and fig. 6, the result data shows that the recovery rate of the succinic acid is less than or equal to 97% when the target substance is detected by using only the liquid phase method, which indicates that a part of free succinic acid in the tobacco tar sample is not detected by the liquid chromatograph, so that the accuracy is not high when the target substance is detected by using only the liquid phase method.

Example 6

In this example, a benzoic acid nicotine salt tobacco tar sample is prepared according to a molar ratio of nicotine to benzoic acid of 1, wherein the theoretical nicotine content is 30.21mg/g, and the theoretical benzoic acid content is 22.76mg/g, and the contents of nicotine and organic acid in the tobacco tar are tested by the following steps:

(1) 2mL of tobacco oil samples are taken and placed in an electronic smoking device, the electronic smoking device is smoked by using a smoking machine, the single-port collection volume is set to be 55mL in the smoking machine, and the smoking time is 3s and is stopped for 27s. The smoke collector is provided with an aerosol outlet of the electronic cigarette appliance and used for absorbing aerosol. And the sealing connection is adopted at any connecting position, so that all the aerosol can pass through the smoke collector. Sucking for 30 mouths, stopping for 5min after sucking, and allowing the aerosol to be completely absorbed by each adsorption layer in the collection device. The collecting device used in this embodiment is specifically shown in fig. 1.

(2) After the flue gas collection device absorbs the aerosol, the adsorption layer 1, the adsorption layer 2 and the adsorption layer 3 are sequentially folded to be strip-shaped towards the aerosol surface, then the strip-shaped aerosol is placed in a 50mL centrifugal tube, 10mL ultrapure water is added, the cover is added for sealing, vortex oscillation is carried out for 5min,10 mL dichloromethane is added, the strip-shaped aerosol is placed in an oscillator, oscillation extraction is carried out for 30min, and standing layering is carried out to obtain an aqueous phase solution and an organic phase solution.

(3) And (3) taking the aqueous phase solution, placing the aqueous phase solution after the aqueous phase solution passes through the membrane in a liquid chromatograph, and calculating the content of the bound nicotine by using an external standard method of a liquid phase method to obtain the content of the bound benzoic acid of 25.03mg/g and 18.92mg/g. The specific test results are shown in fig. 7.

(4) Taking the organic phase solution, placing the organic phase solution after the film is passed in a gas chromatograph, and calculating the content of free nicotine and free benzoic acid by using an external standard method of a gas phase method to obtain the content of 5.13mg/g and 3.78mg/g.

Calculating the total nicotine content and the total organic acid content according to a formula, wherein the total nicotine content = the bound nicotine content measured by a liquid phase method + the free nicotine content measured by a gas phase method, and the total benzoic acid content = the bound benzoic acid content measured by the liquid phase method + the free benzoic acid content measured by the gas phase method. Through calculation, the total nicotine content =25.03+5.13=30.16mg/g, the total benzoic acid content =18.92+3.78=22.70mg/g, the nicotine recovery rate = (30.16/30.21) × 100% =99.84%, and the benzoic acid recovery rate = (22.70/22.76) × 100% =99.7%, which are in line with theoretical values, so that the precision of a test result obtained by using the detection method is high, and the efficiency of proportioning tobacco tar is improved.

Example 7

This example prepared samples of nicotine tartrate nicotine salt tobacco tar at a molar ratio of nicotine to tartaric acid of 1.25, wherein the theoretical nicotine content was 30.13mg/g and the theoretical tartaric acid content was 27.41mg/g, and the contents of nicotine and organic acids in the tobacco tar were tested by the following steps:

accurately weighing 0.1g of tobacco tar sample, placing the tobacco tar sample into a 15mL centrifuge tube with a plug scale, adding 10mL of water solution containing acetonitrile and phosphoric acid, wherein the mass percentage concentration of the acetonitrile is 20%, the mass percentage concentration of the phosphoric acid is 0.5%, placing the centrifuge tube into an oscillator after covering and sealing, oscillating and extracting for 20min, standing, transferring the extract into a brown sample bottle, finally placing the sample into a liquid chromatograph, and calculating by using an external standard method of a liquid phase method to obtain the content of the combined nicotine of 30.01mg/g and the content of the tartaric acid of 27.01mg/g. Nicotine recovery = (30.01/30.13) 100% =99.6%, tartaric acid recovery = (25.36/27.41) × 100% =92.5%. The test results are shown in fig. 8.

As can be seen from fig. 8, neither nicotine nor tartaric acid obtained in the measurement had tailing, but the recovery rate of tartaric acid obtained by the detection was low, and therefore, there was an error in using a liquid chromatograph alone as a target detection device.

Example 8

accurately weighing 0.1g of tobacco tar sample, diluting with isopropanol solution containing an internal standard, oscillating for 30min, testing the tartaric acid nicotine salt tobacco tar sample by a gas phase method, and calculating the test result by using an external standard method to obtain the nicotine content of 29.71mg/g and the tartaric acid content of 0mg/g. Therefore, the nicotine recovery rate was = (29.71/30.13) × 100% =98.61%, no tartaric acid substance was detected, and the test results are shown in fig. 9.

It can be seen that there is an error in using the gas chromatograph alone as the target detection apparatus.

Example 9

The embodiment provides a method for preparing tobacco tar of an electronic cigarette, which specifically comprises the following steps:

(1) A plurality of benzoic acid nicotine salt tobacco tar samples are prepared according to a molar ratio of nicotine to benzoic acid of 1.6-1, respectively, wherein the molar ratio of nicotine to benzoic acid is respectively 1.

(2) Each tobacco tar sample is independently tested, 0.1g of tobacco tar sample is placed in a 50mL centrifugal tube with a plug scale, 10mL of ultrapure water is added, a cover is added for sealing, vortex oscillation is carried out for 5min,10 mL of dichloromethane is added, the mixture is placed in an oscillator, oscillation extraction is carried out for 30min, and standing and layering are carried out to obtain a water phase solution and an oil phase solution. Taking the aqueous phase solution, placing the aqueous phase solution after the film is coated in a liquid chromatograph, measuring the content of the combined nicotine by using an external standard method of a liquid phase method, simultaneously taking the organic phase solution, placing the organic phase solution after the film is coated in a gas chromatograph, and measuring the content of the free nicotine by using the external standard method of the gas phase method.

(3) The percentage of bound nicotine to total nicotine content in each standard tobacco was calculated based on the free and bound nicotine levels tested, as shown in table 1 below and in figure 10.

TABLE 1

As can be seen from table 1 and fig. 10, the free nicotine content decreases with increasing benzoic acid content, and the bound nicotine content increases with increasing benzoic acid content. In benzoic acid nicotine salt, the larger the proportion of benzoic acid, the smaller the proportion of free nicotine, and the larger the proportion of nicotine salt, which indicates that free nicotine and nicotine salt are in dynamic equilibrium, but when the proportion of benzoic acid is increased to a certain extent, the increase of nicotine salt proportion is no longer obvious.

As can be seen from table 1 and fig. 10, when the molar ratio of nicotine to benzoic acid is 1.2 to 1.6, the proportion of the bound nicotine is large, and when the amount of benzoic acid is increased, the proportion of the bound nicotine is small, and therefore, when the electronic cigarette liquid is prepared, the molar ratio of nicotine to benzoic acid can be set to 1.2 to 1.6.

The tobacco smoke samples prepared above were subjected to the smoke test by the panelist smoke specialist and scored as shown in table 1 below:

TABLE 2

Scoring rules are as follows:

throat-hit score detailed rule: the throat hit feeling is strong for 0 to 4 minutes; the throat-hitting feeling is moderate for 4 to 7 minutes; the throat hit feeling is weak for 7 to 10 minutes; fine aerosol smoothness score: the aerosol is smooth and fine for 7 to 10 minutes; slightly blocking the aerosol for 4-7 min; blocking aerosol for 0-4 min; fine grading of aroma intensity: the fragrance is rich and full for 7 to 10 minutes; slightly light fragrance is 4-7 minutes; the fragrance is low and 0 to 4 points.

From the total score of the above sucking panel scores: when the molar ratio of nicotine to benzoic acid is 1:0.6 to 1:1.1, the free nicotine content in nicotine salt is high, and the throat-hitting feeling is strong during smoking; when the molar ratio of nicotine to benzoic acid is higher than 1: after 1.1, the content of free nicotine tends to be stable, the smoking is smooth, the throat-hitting feeling is weak, and the satisfaction is improved. Because the increase of the content of benzoic acid can increase the viscosity of the tobacco tar, which is not beneficial to the flowing atomization of the tobacco tar, and the cost also increases correspondingly, the above experimental tests show that the optimal molar ratio of nicotine to benzoic acid is 1.2-1.6. Therefore, multiple groups of tobacco tar samples are prepared by selecting the optimal molar ratio interval of nicotine and benzoic acid, and expert product smoking is organized, so that the development period for preparing the tobacco tar is shortened, and the efficiency is improved.

Example 10

The embodiment provides a method for preparing electronic cigarette tobacco tar, which specifically comprises the following steps:

(1) Nicotine and succinic acid are prepared according to a molar ratio of 1.3 to 1, respectively, wherein the molar ratio of nicotine and succinic acid is 1.

(2) Each tobacco tar sample is independently tested, 0.1g of tobacco tar sample is taken and placed in a 50mL centrifugal tube with a plug scale, 10mL ultrapure water is added, a cover is added for sealing, vortex oscillation is carried out for 5min,10 mL dichloromethane is added, the mixture is placed in an oscillator, oscillation extraction is carried out for 30min, and standing and layering are carried out to obtain a water phase solution and an oil phase solution. Taking the aqueous phase solution, placing the aqueous phase solution after the film is coated in a liquid chromatograph, measuring the content of the combined nicotine by using an external standard method of a liquid phase method, simultaneously taking the organic phase solution, placing the organic phase solution after the film is coated in a gas chromatograph, and measuring the content of the free nicotine by using a gas phase method.

(3) The percentage of bound nicotine to total nicotine content in each of the standard tobacco products was calculated based on the free and bound nicotine levels tested, as shown in table 3 and figure 11 below.

TABLE 3

As can be seen from table 3 and fig. 11, when the molar ratio of nicotine to succinic acid is 1.

The tobacco tar samples prepared above were smoked by panelist smoking experts and scored as shown in table 4 below:

scoring rules are as follows:

throat-hit score detailed rule: the throat-hitting feeling is strong for 0 to 4 minutes; the throat-hitting feeling is moderate for 4 to 7 minutes; the throat hit feeling is weak for 7 to 10 minutes; fine aerosol smoothness score: the aerosol is smooth and fine for 7 to 10 minutes; slightly blocking the aerosol for 4-7 minutes; blocking aerosol for 0-4 min; fine grading of aroma intensity: the fragrance is rich and full for 7 to 10 minutes; slightly light fragrance for 4-7 minutes; the fragrance is low and 0 to 4 points.

As can be seen from the scores of the expert panel for smoking quality, the optimal molar ratio of nicotine to succinic acid is 1.1-1. Therefore, multiple groups of tobacco tar samples are prepared by selecting the optimal molar ratio interval of nicotine and succinic acid, and expert product smoking is organized, so that the development period for preparing tobacco tar is shortened, and the efficiency is improved.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, so as to understand the technical solutions of the present invention specifically and in detail, but not to be understood as the limitation of the protection scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. It should be understood that the technical solutions provided by the present invention, which are obtained by logical analysis, reasoning or limited experiments, are within the scope of the appended claims. Therefore, the protection scope of the present invention should be subject to the content of the appended claims, and the description and the drawings can be used for explaining the content of the claims.

Claims

1. A method for testing the nicotine content in tobacco tar or aerosol is characterized by comprising the following steps:

mixing a sample to be detected with water, and then adding an organic solvent immiscible with water for extraction to obtain an aqueous phase solution and an organic phase solution; the sample to be detected is tobacco tar or aerosol after smoking the tobacco tar;

testing the content of bound nicotine in the aqueous solution by liquid chromatography;

2. The method for measuring nicotine content in tobacco tar or aerosol according to claim 1, wherein the organic solvent is at least one selected from the group consisting of dichloromethane, chloroform and dichlorobenzene; and/or the presence of a catalyst in the reaction mixture,

the water is deionized water, high-purity water or ultrapure water; and/or the presence of a catalyst in the reaction mixture,

3. The method for testing the nicotine content in the tobacco tar or the aerosol according to claim 1, wherein the sample to be tested is the tobacco tar, and the mass-to-volume ratio of the sample to be tested to water is 1g (100 mL-200 mL).

4. The method for testing the nicotine content in the tobacco tar or the aerosol according to claim 1, wherein the sample to be tested is the aerosol after smoking the tobacco tar, and the sample to be tested is obtained by the following steps:

5. The method of claim 4, wherein the parameters of the puff are: the volume of aerosol sucked by each port is 55mL, the suction time of each port is 3s, and the process is stopped for 27s; and/or the presence of a catalyst in the reaction mixture,

the ratio of the volume of the tobacco tar to the volume of the water is (0.5-2) to 10.

6. The method according to any one of claims 1 to 5, wherein the sample to be tested further contains an organic acid, and the content of the bound organic acid in the aqueous solution is further measured in the step of measuring the content of the bound nicotine in the aqueous solution by liquid chromatography;

in the step of testing the content of free nicotine in the organic phase solution by gas chromatography, the content of free organic acid in the organic phase solution is also tested.

7. The method of claim 6, wherein the organic acid comprises at least one of benzoic acid, tartaric acid, citric acid, succinic acid, fumaric acid, and malic acid.

8. The method for measuring the nicotine content in tobacco tar or aerosol according to any one of claims 1 to 5, wherein the step of measuring the content of the bound nicotine in the aqueous solution by liquid chromatography uses an external standard method; and/or the presence of a catalyst in the reaction mixture,

in the step of testing the content of the free nicotine in the organic phase solution by using the gas chromatography, an external standard method is adopted.

9. The method for measuring the nicotine content in tobacco tar or aerosol according to any one of claims 1 to 5, wherein the procedure parameters of the liquid chromatograph used in the measurement of the content of the bound nicotine in the aqueous solution by liquid chromatography include: the mobile phase A is acetonitrile, and the mobile phase B is phosphoric acid aqueous solution with pH less than 3; gradient program: 0-2.5min, 100% of mobile phase B;3.0 min-5.0 min, the mobile phase B with the volume percentage of 90 percent and the mobile phase A with the volume percentage of 10 percent; 7.0min to 11.0min, wherein the volume percentage of the mobile phase B is 70 percent and the volume percentage of the mobile phase A is 30 percent; 11.5 min-16.0 min,100% of mobile phase B; and/or the like, and/or,

in the process of testing the content of free nicotine in the organic phase solution by using the gas chromatography, the program parameters of the gas chromatograph comprise: sample inlet temperature: 220 ℃; temperature of the detector: 220 ℃; temperature programming: the initial temperature is 100 deg.C, and the temperature is maintained for 0min, and the temperature is raised from 100 deg.C to 230 deg.C at a rate of 20 deg.C/min, and maintained for 5min.

10. The method of claim 9, further comprising:

providing a validation tobacco tar comprising a known amount of bound and/or free nicotine;

adding water into the verified tobacco tar for mixing, and then adding the organic solvent for extraction to obtain a verified water phase solution and a verified organic phase solution;

11. A method for preparing tobacco tar of an electronic cigarette is characterized by comprising the following steps:

testing the free nicotine and bound nicotine levels in a plurality of said standard tobacco products using the method of testing nicotine levels in tobacco products or aerosols of any one of claims 1 to 10;

when the percentage of the combined nicotine in the total nicotine content is taken as a preset value, the corresponding minimum molar ratio of nicotine to organic acid is taken as a preset molar ratio;

and mixing nicotine and organic acid according to the preset molar ratio to prepare the electronic cigarette tobacco tar.

12. The method for formulating e-cigarette liquid of claim 11, wherein the organic acid is benzoic acid, and the predetermined value is 88% to 93%; alternatively, the first and second electrodes may be,

the organic acid is succinic acid, and the preset value is 96.5-98.5%.