A method for testing transfer behavior of a cooling agent in an electronic cigarette and a method for testing content of the cooling agent

Abstract

The present application belongs to the field of test analysis of cooling agents, and particularly relates to a method for testing the transfer behavior of cooling agents in electronic cigarettes and a method for testing the content of cooling agents. The method comprises: under the same gas chromatography-mass spectrometry analysis conditions, testing the content of cooling agents in electronic cigarette atomization extract, aerosol capture liquid and filter extraction liquid, and then calculating the transfer rate of cooling agents in electronic cigarettes; the cooling agents at least comprise WS-3 and menthone glycerin acetal; the gas chromatography-mass spectrometry analysis conditions are: a strong polarity chromatographic column; programmed temperature: the initial temperature is 55-65 DEG C, and then the temperature is increased to 240-260 DEG C at the rate of 10-20 DEG C / min and kept. The method can evaluate the transfer behavior of WS-3, menthone glycerin acetal and other new compound cooling agents as a whole, and has important significance for the development and performance evaluation of electronic cigarette related products.

Description

Technical Field

[0001] This invention belongs to the field of testing and analysis of cooling agents, specifically relating to a method for testing the transfer behavior of cooling agents in electronic cigarettes and a method for testing the content of cooling agents. Background Technology

[0002] In recent years, e-cigarette products containing cooling agents have gained widespread attention in the market, and their "icy" taste has become one of the mainstream consumer choices. The transfer behavior of cooling agents from e-cigarette atomized substances to aerosols directly determines the intensity and consistency of the cooling sensation actually perceived by consumers during inhalation. This is of great significance from both the perspective of sensory experience and product formulation development.

[0003] Commonly used cooling agents for cigarettes include D,L-menthol, L-menthone, menthyl acetate, menthyl lactate, isoprene, N-ethyl-p-menthyl-3-carboxamide (WS-3, CAS No. 9711-79-0), and N,2,3-trimethyl-2-isopropylbutyramide (WS-23, CAS No. 51115-67-4). Existing technologies have been used to study the transfer behavior of cooling agents in electrically heated cigarettes and conventional cigarettes. For example, Wang Ziyan et al. (Tobacco Science and Technology, October 2020, Vol. 53, No. 10) used gas chromatography-mass spectrometry (GC-MS) to determine the content and mainstream smoke release of nine cooling agents (L-menthone, isomenthone, isomenthol, D,L-menthol, menthyl acetate, menthyl lactate, WS-3, WS-5 and WS-23) in tobacco shreds / reconstituted tobacco leaves of two types of cigarettes (electrically heated cigarettes and traditional cigarettes, 9 samples each), and calculated the smoke transfer rate of seven cooling agents.

[0004] The cooling agent in e-cigarettes is transferred into the aerosol through electric heating and atomization rather than combustion. This working method determines that the transfer behavior of the cooling agent in e-cigarettes is quite different from that in traditional cigarettes. Therefore, it is necessary to re-establish suitable testing methods based on the inhalation characteristics of e-cigarettes.

[0005] Furthermore, the use of multiple cooling agents in combination is becoming increasingly common. This combination can overcome the limitations of a single cooling agent and, through the complementarity of different components in terms of evaporation rate and cooling intensity, create a three-dimensional sensory experience with distinct "pre-, mid-, and post-absorption stages," making the cooling sensation more rounded and harmonious.

[0006] In addition to menthol-based cooling agents, new combinations of cooling agents are constantly emerging. For example, the combination of WS-3 and menthone glycerol ketal (6-isopropyl-9-methyl-1,4-dioxospiro[4,5]decane-2-methanol) utilizes WS-3 to provide a strong and lasting cooling impact, while the menthol glycerol ketal uses its smooth and rounded properties to modify the taste and add flavor. Combined with the similar thermal stability of the two, it has become an ideal combination for creating high-quality cooling e-cigarettes.

[0007] WS-3 and menthone glycerol ketal have similar polarities, which can easily lead to overlapping chromatographic peaks and poor peak shape, making baseline separation impossible. This makes it difficult to achieve effective separation and accurate quantification of WS-3 and menthone glycerol ketal when analyzing multiple cooling agents simultaneously. This poses a significant challenge to the efficient analysis of novel cooling agent combinations in e-cigarettes.

[0008] Regarding analytical methods, Chinese invention patent application CN 116539737 A, published on August 4, 2023, discloses a method for analyzing heated cigarette cooling agents using gas chromatography-quadrupole time-of-flight mass spectrometry (GC-QTOF MS). This method enables the determination of 16 target cooling agents in heated cigarettes, including isomentheptyl alcohol, menthone, menthofuran, neomentheptyl alcohol, D,L-mentheptyl alcohol, piperonone, WS-23, menthyl acetate, menthyl lactate, mentholactone, menthyl isovalerate, WS-3, WS-10, menthyl succinate, WS-5, and WS-12.

[0009] The aforementioned quadrupole / time-of-flight analyzer combines quadrupole mass selection with time-of-flight mass spectrometry (TOF-MS) for high-resolution detection. The quadrupole facilitates ion screening and transport, while the time-of-flight analyzer enables high-resolution ion detection. Due to its high resolution, the TOF-MS analyzer can accurately identify specific compounds in complex mixture samples. However, GC-QTOF MS analysis requires establishing a Personal Compound Database (PCDL) containing retention times, elemental composition, and corresponding theoretically accurate mass numbers for qualitative analysis. This process is cumbersome, costly, and impractical for routine analysis of cooling agents in e-cigarettes. Summary of the Invention

[0010] The purpose of this invention is to provide a method for testing the transfer behavior of cooling agents in electronic cigarettes, in order to solve the problem that existing gas chromatography-mass spectrometry analysis methods cannot accurately evaluate the transfer rate of novel compound cooling agents such as WS-3 and menthone glycerol ketal.

[0011] The second objective of this invention is to provide a method for testing the content of cooling agents in electronic cigarette atomized products, thereby solving the problem that existing gas chromatography-mass spectrometry analysis methods cannot achieve baseline separation and accurate quantification of novel compound cooling agents such as WS-3 and menthol glycerol ketal in electronic cigarettes.

[0012] The third objective of this invention is to provide a method for testing the content of cooling agents in e-cigarette aerosols, thereby solving the problem that existing gas chromatography-mass spectrometry analysis methods cannot achieve baseline separation and accurate quantification of novel compound cooling agents such as WS-3 and menthone glycerol ketal in e-cigarette aerosols.

[0013] To achieve the above objectives, the technical solution of the method for testing the transfer behavior of cooling agents in electronic cigarettes according to the present invention is as follows:

[0014] A method for testing the transfer behavior of cooling agents in electronic cigarettes, comprising the following steps:

[0015] (1) Add methanol and internal standard to the e-cigarette atomizer to extract and obtain e-cigarette atomizer extract; inhale the e-cigarette and collect it with a methanol trap and a filter trap connected in series. Mix the solution in the methanol trap with the internal standard to obtain aerosol collection liquid; add methanol and internal standard to the collection of the filter trap to extract and obtain filter extract.

[0016] (2) The content of cooling agent in each sample solution was tested under the same gas chromatography-mass spectrometry analysis conditions, and then the transfer rate of cooling agent in electronic cigarettes was calculated.

[0017] The cooling agent contains at least WS-3 and menthone glycerol ketal; the gas chromatography-mass spectrometry analysis conditions are: a highly polar chromatographic column; the temperature program is: an initial temperature of 55~65℃, followed by an increase of 10~20℃ / min to 240~260℃ and holding.

[0018] This invention is an improved invention. It addresses the difficulty in separating electronic cigarette matrix and WS-3 and menthone glycerol ketal by using a highly polar chromatographic column with optimized temperature program conditions. This enables baseline separation of novel compound cooling agents such as WS-3 and menthone glycerol ketal. The chromatographic peaks of all compounds are sharp and symmetrical, achieving accurate quantification and accurate evaluation of transfer rate.

[0019] Meanwhile, by comparing the relative standard deviations of the extraction effects of various extraction solvents on target cooling agents such as (-)-menthyl acetate, menthone glycerol ketal, and WS-23, methanol showed better extraction effect, which is beneficial for the accurate analysis of multiple cooling agents at the same time.

[0020] This method can provide an overall evaluation of the transfer behavior of novel compound cooling agents such as WS-3 and menthone glycerol ketal, which is of great significance for the research, development and performance evaluation of e-cigarette related products.

[0021] Preferably, the cooling agent includes p-menthane-3,8-diol and WS-27. Both p-menthane-3,8-diol and WS-27 are novel cooling agents, and this method can simultaneously achieve accurate quantitative analysis of these novel cooling agents.

[0022] More preferably, the cooling agent includes one or more of (+)-isopreneol, L-menthone, isomenthone, D,L-menthone, WS-23, and (-)-menthyl acetate. The boiling points of (+)-isopreneol and L-menthone, isomenthone and D,L-menthone, and WS-23 and (-)-menthyl acetate are quite close, approximately 90°C, 216°C, and 230°C respectively, making baseline separation difficult. Furthermore, these three pairs of compounds are common cooling agents; simultaneously analyzing these cooling agent varieties further demonstrates the adaptability of this method, facilitating systematic and comprehensive analysis of electronic cigarette cooling agents.

[0023] Preferably, the cooling agents comprise 13 types, namely L-menthone, isomenthone, (-)-menthyl acetate, (+)-isomenthyl alcohol, D,L-menthyl alcohol, piperonone, WS-23, WS-27, menthyl lactate, p-menthane-3,8-diol, WS-3, menthone glycerol ketal, and WS-5. These cooling agents include all four types specified in Appendix A of the national standard for electronic cigarettes (GB 41700): menthyl acetate, D,L-menthyl alcohol, WS-23, and WS-3 (WS-3 and WS-23 are currently the most widely used carboxamide cooling agents); they also contain many cooling agent intermediates (isomenthyl alcohol and menthone can be reduced to menthol, and isomenthyl alcohol is an indispensable intermediate in the synthesis of menthol); menthyl lactate is usually an important component of compound cooling agents. This method enables simultaneous analysis of the above 13 types of cooling agents, improving the efficiency of routine analysis of various common and novel cooling agents in e-cigarettes and reducing analysis costs.

[0024] More preferably, isomenthone, L-menthone, (-)-menthyl acetate, (+)-isomenthyl alcohol, and D,L-menthyl alcohol use acetophenone-D8 as internal standards, while the remaining compounds use 2',2-bipyridine-D8 as internal standards. Using this internal standard quantification method ensures high quantitative accuracy because the retention times of the internal standard compounds are close to those of the target analytes, resulting in similar quantification accuracy.

[0025] Preferably, the highly polar chromatographic column is HP-INNOWAX, the initial temperature is held for 1-2 minutes, and the temperature is raised to 240-260°C and held for 6-7 minutes. Under these preferred chromatographic conditions, the analysis time is less than 20 minutes, achieving good separation results in a short time and meeting the requirements of a rapid and efficient method.

[0026] Preferably, the transfer rate is calculated according to the following formula:

[0027]

[0028] TR2 represents the transfer rate (%) of each cooling agent from e-cigarette vaporized material to e-cigarette aerosol.

[0029] C 气相 C 粒相 and C 雾化物 The concentrations, in μg / mL, of each cooling agent in the e-cigarette aerosol capture liquid, e-cigarette filter extract, and e-cigarette atomized products, respectively.

[0030] V 气相 V 粒相 、 and V 雾化物 The volumes, in mL, are respectively the e-cigarette aerosol capture liquid, e-cigarette filter extract, and e-cigarette atomized extract.

[0031] m 雾化物 m 弹前 and m 弹后 The quantities are, in grams, the mass of the electronic cigarette atomized material, the mass of the cartridge before inhalation, and the mass of the cartridge after inhalation.

[0032] The technical solution of the method for testing the content of cooling agent in electronic atomized products of the present invention is as follows:

[0033] A method for testing the content of cooling agent in electronic cigarette vaporizers, comprising the following steps:

[0034] S1. Add methanol and internal standard to the e-cigarette vaporized material for extraction to obtain e-cigarette vaporized material extract;

[0035] S2. Gas chromatography-mass spectrometry analysis of the e-cigarette vapor extract to determine the content of the cooling agent; the cooling agent contains at least WS-3 and menthone glycerol ketal; the gas chromatography-mass spectrometry analysis conditions are: a highly polar chromatographic column; the temperature program is: an initial temperature of 55~65℃, followed by a temperature increase of 10~20℃ / min to 240~260℃ and holding.

[0036] The present invention provides a method for determining the content of cooling agents in electronic cigarette atomized products. Through optimized chromatographic columns and programmed temperature conditions, it achieves GC-MS analysis of novel compound cooling agents such as WS-3 and menthone glycerol ketal in electronic cigarettes. This method solves the separation problem of substances with similar polarity and thermal stability, such as WS-3 and menthone glycerol ketal, and enables accurate quantification of the content of various compound cooling agents. Compared to GC-QTOF MS, it simplifies the analytical procedure and reduces analytical costs.

[0037] Preferably, the cooling agent includes one or more of (+)-isopreneol, L-menthone, isomenthone, D,L-menthone, WS-23, (-)-menthyl acetate, piperone, p-menthane-3,8-diol, WS-27, menthyl lactate, and WS-5.

[0038] Preferably, the highly polar chromatographic column is HP-INNOWAX, the initial temperature is held for 1-2 minutes, and the temperature is raised to 240-260°C and held for 6-7 minutes.

[0039] The technical solution of the method for testing the content of cooling agent in electronic cigarette aerosol of the present invention is as follows:

[0040] A method for testing the content of cooling agent in electronic cigarette aerosol, comprising the following steps:

[0041] a) Inhale an electronic cigarette and collect it using a methanol trap and a filter trap connected in series. Mix the solution in the methanol trap with the internal standard to obtain an aerosol collection solution. Add methanol and the internal standard to the collection in the filter trap for extraction to obtain a filter extract solution.

[0042] b) The content of cooling agent in the aerosol trap and filter extract was tested using the same gas chromatography-mass spectrometry (GC-MS) analysis conditions; the cooling agent contained at least WS-3 and menthone glycerol ketal; the GC-MS analysis conditions were: a highly polar column; the temperature program was: an initial temperature of 55-65°C, followed by a temperature increase of 10-20°C / min to 240-260°C and a holding temperature.

[0043] The method for testing the content of cooling agents in e-cigarette aerosols of the present invention, for the first time, simultaneously captures particulate matter and gaseous matter when testing the content of cooling agents in e-cigarette aerosols, and has the advantages of high capture efficiency and accurate test results. In addition, this method achieves effective separation of cooling agents such as WS-3 and menthone glycerol ketal in e-cigarette aerosols, improving the quantitative accuracy of the above-mentioned cooling agents in e-cigarette aerosols.

[0044] Preferably, the cooling agent includes one or more of (+)-isopreneol, L-menthone, isomenthone, D,L-menthone, WS-23, (-)-menthyl acetate, piperone, p-menthane-3,8-diol, WS-27, menthyl lactate, and WS-5.

[0045] Preferably, the highly polar chromatographic column is HP-INNOWAX, the initial temperature is held for 1-2 minutes, and the temperature is raised to 240-260°C and held for 6-7 minutes. Attached Figure Description

[0046] Figure 1 The separation effect of 13 cooling agents and 2 internal standards in this invention on a DB-624UI chromatographic column is shown. The compounds corresponding to No. 1-15 are L-menthone, isomenthone, (-)-menthyl acetate, (+)-isomenthyl alcohol, D,L-menthyl alcohol, acetophenone-D8 (internal standard 1), piperone, WS-23, WS-27, menthyl lactate, p-menthane-3,8-diol, 2'2-bipyridine-D8 (internal standard 2), WS-3, menthone glycerol ketal and WS-5;

[0047] Figure 2 The separation effect of 13 cooling agents and 2 internal standards in this invention on a DB-5MS column is shown. The compounds corresponding to No. 1-15 are the same as those in the DB-5MS column. Figure 1 ;

[0048] Figure 3 The separation effect of 13 cooling agents and 2 internal standards in this invention on the HP-INNOWAX chromatographic column is shown. The compounds corresponding to No. 1-15 are the same as those in the previous invention. Figure 1 ;

[0049] Figure 4 The separation effect of 13 cooling agents and 2 internal standards in this invention under the first programmed temperature rise condition is shown. The compounds corresponding to No. 1-15 are the same. Figure 1 ;

[0050] Figure 5 This invention demonstrates the separation effect of 13 cooling agents and 2 internal standards under the second programmed temperature rise condition. Compounds 1-15 correspond to the same... Figure 1 ;

[0051] Figure 6 This invention demonstrates the separation effect of 13 cooling agents and 2 internal standards under the third programmed temperature rise condition. Compounds 1-15 correspond to the same... Figure 1 ;

[0052] Figure 7 The separation effect of 13 cooling agents and 2 internal standards in this invention under the fourth temperature program is shown. Compounds 1-15 correspond to the same... Figure 1 ;

[0053] Figure 8 The separation effect of 13 cooling agents and 2 internal standards in this invention under the fifth temperature program condition is shown. Compounds 1-15 correspond to the same... Figure 1 ;

[0054] Figure 9 This is the result of optimizing the extraction solution type using actual samples in this invention;

[0055] Figure 10 This is a typical chromatogram obtained from analyzing actual samples in this invention. Detailed Implementation

[0056] (I) Preferred embodiments of the method for testing the transfer behavior of cooling agents in electronic cigarettes and the method for testing the content of cooling agents of the present invention

[0057] To enable routine analysis and quality optimization of cooling agents in e-cigarettes that use a variety of existing cooling agent mixtures, and to adapt to the analysis of novel cooling agent combinations, this invention provides a gas chromatography-mass spectrometry (GC-MS) method covering 13 cooling agents. This method can accurately determine and quantify multiple groups of cooling agents with similar polarity and thermal stability, such as WS-3 with menthone glycerol ketal, (+)-isomentheptyl alcohol and L-menthone, isomenthone and D,L-menthol, WS-23 and (-)-menthyl acetate, as well as novel cooling agents such as menthane-3,8-diol and WS-27. This allows for the content testing and transfer behavior analysis of various cooling agent combinations in e-cigarettes.

[0058] The difficulty in simultaneously analyzing the above 13 cooling agents lies in the presence of easily pyrolytic substances (such as isomenthone and isomenthol); the significant differences in polarity among the target cooling agents, making it impossible to simultaneously guarantee a high extraction rate; and the presence of combinations of cooling agents that are difficult to separate, such as WS-3 and menthone glycerol ketal.

[0059] Under the aforementioned constraints, this invention, through comparison of seven extraction solvents, determined that methanol exhibits the best extraction rate and is the optimal solvent for achieving near-perfect extraction of various target cooling agents. By comparing three chromatographic columns and matching at least five temperature programs, effective separation and accurate quantification of each target cooling agent were achieved. The optimization of the solvent extraction and chromatographic-mass spectrometry analysis conditions fully considered the influence of pyrolysis temperature, ultimately determining the key control conditions.

[0060] Compared to existing GC-MS methods, this method can simultaneously analyze a wider range of cooling agents, including combinations of cooling agents that are difficult to separate, such as WS-3 and menthone glycerol ketal. This demonstrates better accuracy than existing technologies, resulting in unexpected technical benefits. Based on these benefits, a comprehensive analysis of various mainstream cooling agent combinations in e-cigarettes can be achieved, providing efficient and economical basic data for quality monitoring and style optimization of e-cigarettes containing cooling agents.

[0061] When extracting the cooling agent from e-cigarette vapors, add 50-60 mL of methanol for every 0.5 g of sample. The internal standard can be added in the form of an internal standard solution; when adding 50-60 mL of methanol, add 0.5-0.6 mL of the internal standard solution. The solvent for the internal standard solution can be methanol, etc. The concentration of the internal standard in the sample solution should be controlled to be 2.0-4.0 μg / mL. Extraction is preferably performed by shaking, and the shaking extraction time can be 40-60 min.

[0062] In the capture of cooling agents in e-cigarette aerosols, two tandem traps containing methanol and glass fiber filters are used to sequentially capture the cooling agents. During extraction, the solution from each trap is taken and mixed with an internal standard to obtain the aerosol capture solution. Methanol and the internal standard are then added to the collection in the filter trap for extraction, yielding the filter extract.

[0063] When using the electronic cigarette, you can take 40-50 puffs, with 25-30 mL of methanol in each trap. When extracting the collected material from the trap, add 25-30 mL of methanol. The extraction process preferably uses shaking extraction, which can last for 40-60 minutes.

[0064] For GC-MS analysis, the chromatographic column was HP-INNOWAX; the temperature program was as follows: initial temperature 55~65℃, hold for 1~2 min, increase to 240~260℃ at a rate of 10~20℃ / min and hold for 6~7 min.

[0065] The splitless injection mode was used with an injection volume of 1.0 μL and a solvent cut-off time of 5.5 min. High-purity He was used as the carrier gas at a flow rate of 1.0 mL / min. The temperatures of the injection port, ion source, and transfer line were 250℃, 230℃, and 250℃, respectively. The mass spectrometer ionization source was an EI source with an ionization voltage of 70 eV. The scanning mode was selected ion scanning.

[0066] The preferred embodiments of the present invention will be illustrated below with reference to examples.

[0067] Example 1

[0068] The method for testing the transfer behavior of cooling agents in electronic cigarettes in this embodiment adopts the following steps:

[0069] The first step was the preparation of a series of standard solutions: using methanol as the solvent and 13 cooling agent standards as solutes—L-menthone, isomenthone, (-)-menthyl acetate, (+)-isomenthyl alcohol, D,L-menthyl alcohol, piperonone, WS-23, WS-27, menthyl lactate, p-menthane-3,8-diol, WS-3, 6-isopropyl-9-methyl-1,4-dioxospiro[4,5]decane-2-methanol (i.e., menthone glycerol ketal) and WS-5—as well as acetophenone-D8 and 2'2-bipyridine-D8 as internal standards, a series of standard solutions with the following concentrations were prepared: 0.1, 0.2, 0.5, 1.0, 2.0, 5.0, 10.0, and 20.0. The concentrations of piperonitrile and WS-5 were 0.45, 0.90, 2.25, 4.50, 9.00, 22.50, 45.00 and 90.00 μg / mL, and the internal standard concentration in all standard series solutions was 2.0 μg / mL.

[0070] The second step is the preparation of the sample solution: methanol and an internal standard are added to the e-cigarette vapor to extract the vapor, obtaining an e-cigarette vapor extract; the e-cigarette is inhaled and collected using a methanol trap and a filter trap connected in series; the solution in the methanol trap is mixed with the internal standard to obtain an aerosol collection solution; methanol and an internal standard are added to the collection in the filter trap for extraction, obtaining a filter extract. Specifically:

[0071] Extraction of cooling agent from e-cigarette vapors: Weigh 0.50 g of sample into a 50 mL centrifuge tube, add 0.50 mL of internal standard solution (solvent is methanol, internal standard concentration is 200 μg / mL) and 50 mL of methanol, seal the tube, and place it on a vortex mixer to extract at a rate of 2000 rpm for 40 min. After standing, collect the supernatant for later use.

[0072] Collection and extraction of cooling agents in e-cigarette aerosol: The e-cigarette cartridges were weighed and their mass recorded before inhalation. The e-cigarette was inhaled using an e-cigarette device according to the conditions specified in GB 41700. Two series-connected traps containing 25.0 mL of methanol and a glass fiber filter were used to sequentially collect the cooling agents from the e-cigarette aerosol. During inhalation, the two traps were connected in series between the e-cigarette holder and the trap, and the glass fiber filter was placed inside the trap. The e-cigarette was then inhaled under the following conditions: inhalation duration 3.0 s, inhalation volume 55.0 mL, inhalation frequency 30.0 s, and the inhalation flow rate was shown as a rectangle.

[0073] After 50 puffs of the e-cigarette, the cartridge was weighed again and the mass was recorded. 5.0 mL of solution was taken from each trap and an internal standard (0.10 mL of 200 μg / mL internal standard solution) was added, mixed thoroughly, and set aside. The glass fiber filter was removed from the trap, and the inner wall of the trap was wiped clean with a new glass fiber filter. Both were placed in a container, and 25 mL of methanol and 0.25 mL of internal standard were added. Extraction was performed by shaking for 40 min. After standing, the supernatant was collected and set aside.

[0074] The third step involved gas chromatography-mass spectrometry (GC-MS) analysis of the standard series solutions and sample solutions under the same conditions: GC-MS conditions were as follows: HP-INNOWAX column, 30 m × 0.25 mm × 0.25 μm; temperature program: initial temperature 60℃, held for 1.0 min, increased to 240℃ at a rate of 20℃ / min and held for 6.0 min; splitless injection mode, injection volume 1.0 μL, solvent cut-off time 5.5 min; high-purity He as carrier gas, flow rate 1.0 mL / min; injection port, ion source, and transfer line temperatures 250℃, 230℃, and 250℃, respectively; EI source; ionization voltage 70 eV; selected ion scan mode. The retention times and monitored ion mass-charge ratios of the 13 target analytes and 2 internal standards under the above conditions are shown in Table 1 below.

[0075] Table 1. Retention times of target analytes and internal standards, and monitoring ions in the method of this invention.

[0076]

[0077] Step 4: Characterization of cooling agent transfer behavior:

[0078] (1) Quantification of cooling agents in the sample: The ratio of the peak area of ​​each cooling agent in the standard series solution to the peak area of ​​the internal standard was plotted on the ordinate (isomenthone, L-menthone, (-)-menthyl acetate, (+)-isomenthyl alcohol and D,L-menthyl alcohol were internally standardized with acetophenone-D8, and the concentration of each cooling agent in the standard series solution was internally standardized with 2'2-bipyridine-D8 as the internal standard for the other compounds), and the concentration of each cooling agent in the standard series solution was plotted on the abscissa. The results are shown in Table 2. Based on the ratio of the peak area of ​​each cooling agent in the sample solution to the peak area of ​​the internal standard, the content of each cooling agent in the sample was obtained according to the working curve.

[0079] The concentrations corresponding to the signal-to-noise ratio (S / N) of the target analyte at 3 and 10 are defined as the limits of detection and the limits of quantitation. The linear range, working curve, limit of quantitation, and limit of detection of the target analyte in this invention are shown in Table 2.

[0080] Table 2. Linear range, working curve, limit of quantitation, and limit of detection of the target analyte in this invention.

[0081]

[0082] To examine the repeatability of this method, samples with low, medium, and high concentrations (2, 20, and 100 times the lowest linear range of each target analyte, respectively) were injected. Five samples prepared within one day were measured, and the intraday relative standard deviation at different concentrations was calculated. Samples prepared over three consecutive days were extracted, and the interday relative standard deviation at different concentrations was calculated.

[0083] The results are shown in Table 3. The intra-day and inter-day precision of the target analyte at different concentrations were less than 6.6% and 7.3%, respectively. This indicates that the sensitivity and repeatability of the method can meet the requirements for detecting the content of cooling agents.

[0084] Table 3. Repeatability data of the target analyte in this invention

[0085]

[0086] (2) Calculation of the transfer rate of cooling agents in e-cigarettes: Substitute the contents of each cooling agent in the e-cigarette atomized product, the mass of the e-cigarette cartridge before and after smoking, the contents of each cooling agent in the aerosol collection liquid and the filter extract into the following formula to calculate the transfer rate of cooling agents in e-cigarettes.

[0087]

[0088] TR2 represents the transfer rate (%) of each cooling agent from e-cigarette vaporized material to e-cigarette aerosol.

[0089] C 气相 C 粒相 and C 雾化物 The concentrations, in μg / mL, of each cooling agent in the e-cigarette aerosol capture liquid, e-cigarette filter extract, and e-cigarette atomized products, respectively.

[0090] V 气相 V 粒相 、 and V 雾化物 The volumes, in mL, are respectively the e-cigarette aerosol capture liquid, e-cigarette filter extract, and e-cigarette atomized extract.

[0091] m 雾化物 m 弹前 and m 弹后 The quantities are, in grams, the mass of the electronic cigarette atomized material, the mass of the cartridge before inhalation, and the mass of the cartridge after inhalation.

[0092] Example 2

[0093] The method for testing the content of cooling agent in e-cigarette vaporized products in this embodiment involves adding methanol and an internal standard to the e-cigarette vaporized products for extraction, obtaining an e-cigarette vaporized product extract, and then performing gas chromatography-mass spectrometry analysis on the e-cigarette vaporized product extract to quantify the cooling agent in the sample. The specific implementation details are the same as the analysis process of the e-cigarette vaporized product extract in Example 1.

[0094] Example 3

[0095] The method for testing the content of cooling agents in electronic cigarette aerosols in this embodiment is to use the method in Example 1 to perform gas chromatography-mass spectrometry analysis on the aerosol collection liquid and filter extract to test the types and contents of each cooling agent in the sample.

[0096] (ii) Comparative Example

[0097] Comparative Example 1: Selection of Gas Chromatography Column

[0098] To achieve ideal separation results, this study investigated the separation performance of three different coated and polar columns using a mixed standard solution. Specific information on the columns and temperature programs are shown in Table 4. The total ion chromatograms of the preliminary separation of the mixed standard solution on the three columns are shown below. Figure 1 .

[0099] Table 4. Column Specifications

[0100]

[0101] Depend on Figure 1 It can be seen that the response value of menthone glycerol acetal (compound 14) is small, and the chromatographic peak has a tail.

[0102] Furthermore, compared to the other two columns, the target analytes exhibited longer overall retention times on the DB-624UI column: all 12 target analytes and 2 internal standard compounds were eluted within 25 minutes, with the last compound (WS-5) retaining for over 34 minutes. In contrast, all compounds on the other two columns were eluted within 20 minutes. This is likely due to the longer column length and thicker membrane of the DB-624UI, resulting in stronger retention of the target compounds.

[0103] Depend on Figure 2 It can be seen that the relative response value of menthone glycerol acetal (compound 14) is improved compared with the DB-624UI column, but it leads to poor separation from WS-3 (compound 13). At the same time, the relative response value of 2'2-bipyridine-D8 (internal standard 2, compound 12) is found to be significantly reduced, which may bring uncertainty to the subsequent quantification.

[0104] Meanwhile, since the boiling points of (+)-isoprene and L-menthone, isoprene and D,L-menthone, and WS-23 and (-)-menthyl acetate are relatively close, with boiling points of approximately 90℃, 216℃ and 230℃ respectively, these three pairs of compounds could not be baseline separated on the DB-5MS column.

[0105] Depend on Figure 3 It can be seen that all compounds can be well separated on the HP-INNOWAX column, and the analysis time is less than 20 minutes, which meets the requirements of a rapid and efficient method. Therefore, subsequent experiments were carried out on the HP-INNOWAX column.

[0106] Comparative Example 2: Optimization of Program Temperature Rise Conditions

[0107] To achieve effective separation of all target compounds in a shorter time, the temperature program was investigated based on the previously optimized column, including optimization of the initial column temperature and heating rate, as detailed in Table 5.

[0108] Table 5. Heating Program

[0109]

[0110] Generally, a higher initial column temperature can reduce chromatographic separation time; however, in this invention, the applicant unexpectedly discovered that, as Figure 4 As shown, when the initial temperature is 100℃, the chromatographic peaks of the seven compounds with the earliest retention times exhibit poor peak shape and cannot be separated; for example... Figure 5 As shown, when the initial temperature is reduced to 80℃, the number of compounds with poor peak shape decreases to 4; Figure 6 As shown, when the initial temperature was further reduced to 60℃, the chromatographic peaks of all compounds were sharp and symmetrical. This is likely because compounds with earlier retention times undergo low-temperature condensation at the column head, reducing diffusion at high temperatures and thus resulting in better separation. To achieve good separation within a shorter time, the initial temperature of the chromatographic column was set to 60℃.

[0111] Appropriately increasing the heating rate can also reduce the overall chromatographic analysis time. Therefore, with the initial column temperature set at 60℃, different heating rates were investigated. The results are as follows: Figures 6-8As shown, with the continuous increase in heating rate, the elution time of all compounds decreased from 22 minutes to 14 minutes. Considering that the separation degree of (-)-menthyl acetate and (+)-isomenthyl alcohol, 2',2-bipyridine-D8 and WS-3 decreased with the continuous increase in heating rate, baseline separation of the two groups of compounds could be basically achieved at a heating rate of 20 °C / min, and all compounds could be eluted in a relatively short time (14 minutes). Therefore, a faster heating rate was not considered, and the temperature program rate was set to 20 °C / min.

[0112] Comparative Example 3: Optimization of Extract Type

[0113] The optimization of the extractant type was based on the optimization results of cigarettes. Taking a certain domestic cigarette as the research object, the extraction effects of seven solvents with different polarities (methanol, ethanol, isopropanol, ethyl acetate, acetone, dichloromethane, and cyclohexane) on the cooling agent in the actual sample were investigated.

[0114] Crush the flavor capsules from two cigarettes, cut the whole cigarette into small pieces of 0.5-1.0 cm, fix the extraction volume at 50 mL, shake and extract for 15 minutes, collect the supernatant after standing, and analyze it by gas chromatography-mass spectrometry. The results are as follows. Figure 9 As shown.

[0115] Seven cooling agents were detected in the cigarette. The relative standard deviations (RSDs) of most compounds under different extraction solvents ranged from 7.2% to 10.9%, indicating little difference in extraction efficiency between different solvents. For the compounds with significantly different RSDs (RSDs) under different extraction solvents, namely (-)-menthyl acetate, menthone glycerol ketal, and WS-23 (RSDs ranging from 17.9% to 33.8%), methanol showed better extraction efficiency. Therefore, methanol was ultimately selected as the extraction solvent.

[0116] Comparative Example 4: Analysis of Cooling Agent Transfer in Electronic Cigarettes

[0117] The results of analyzing two e-cigarette aerosols and their corresponding e-cigarette compounds are shown in Table 6. A typical chromatogram of sample H is shown below. Figure 10 As shown, under optimized conditions, the matrix does not interfere with the quantification of the target analyte, indicating that this method has good selectivity.

[0118] Table 6. Analysis of e-cigarette smoke compounds and aerosols (μg / mL) in this invention

[0119]

[0120] The results show that WS-23 and WS-3 were detected in both e-cigarette atomized samples. Based on the sample weights (0.4938 g for sample G and 0.5029 g for sample H) and the extraction volumes (50 mL for both samples G and H), the contents of WS-23 and WS-3 in the atomized sample G were calculated to be 0.26 mg / g and 0.09 mg / g, respectively; while the contents of WS-23 and WS-3 in the atomized sample H were 0.58 mg / g and 0.31 mg / g, respectively.

[0121] Meanwhile, the relevant target analytes in the e-cigarette vapors were analyzed using existing standard methods (https: / / www.ztri.com.cn / images / dzy / 2022 / 06 / 08 / B693CCA589E86BE866F11CF3E61B40BD.pdf). The results were as follows: the contents of (-)-menthyl acetate, D,L-menthol, WS-23, and WS-3 in sample G vapors were 0 mg / g, 0 mg / g, 0.30 mg / g, and 0.08 mg / g, respectively; the contents of (-)-menthyl acetate, D,L-menthol, WS-23, and WS-3 in sample G vapors were 0 mg / g, 0 mg / g, 0.57 mg / g, and 0.36 mg / g, respectively. It can be seen that the test results of the relevant cooling agents in the vapors of samples G and H using the method of this application and existing standard methods are consistent, proving the accuracy of this method.

[0122] The mass of sample G cartridge before and after inhalation was 68.3416 g and 68.0425 g, respectively, while the mass of sample H cartridge before and after inhalation was 32.2415 g and 31.9418 g, respectively. Substituting these results into the transfer rate formula, the transfer values ​​of different cooling agents in e-cigarettes to the aerosol can be obtained. The results are shown in Table 7.

[0123] Table 7. Transfer rate (%) of cooling agent from electronic cigarette vapor to aerosol in this invention

[0124]

[0125] The results show that due to differences in heating efficiency caused by the design parameters of e-cigarettes, coupled with variations in the physicochemical properties of the cooling agents themselves, the transfer rates of different cooling agents within the same sample or the same cooling agent in different samples all differ. It should be noted that the transfer efficiency of WS-3 in sample H was 101.76%, which may be due to testing error.

[0126] The high transfer efficiency of WS-23 in both e-cigarette samples is likely due to its low boiling point and easy volatilization upon heating. Meanwhile, the near 100% transfer efficiency of the two cooling agents in sample H demonstrates not only the accuracy and rationality of this method in analyzing the transfer rate of cooling agents in e-cigarettes, but also that the design parameters of sample H have high heating efficiency, which is beneficial for the transfer of related compounds from the atomized material to the aerosol. These methods and data can provide technical guidance for the design, development, and quality evaluation of e-cigarette products.

[0127] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for testing the transfer behavior of cooling agents in electronic cigarettes, characterized in that, Includes the following steps: (1) Add methanol and internal standard to the electronic cigarette smoke to extract the electronic cigarette smoke extract; inhale the electronic cigarette and collect it with a methanol trap and a filter trap connected in series. Mix the solution in the methanol trap with the internal standard to obtain an aerosol collection solution. Methanol and internal standard were added to the precipitate of the filter trap for extraction to obtain the filter extract. (2) The content of cooling agent in each sample solution was tested under the same gas chromatography-mass spectrometry analysis conditions, and then the transfer rate of cooling agent in electronic cigarettes was calculated. The cooling agent contains at least WS-3 and menthone glycerol ketal; the gas chromatography-mass spectrometry analysis conditions are: a highly polar chromatographic column; the temperature program is: an initial temperature of 55~65℃, followed by an increase of 10~20℃ / min to 240~260℃ and holding.

2. The method for testing the transfer behavior of cooling agents in electronic cigarettes as described in claim 1, characterized in that, The cooling agent includes p-menthane-3,8-diol and WS-27.

3. The method for testing the transfer behavior of cooling agents in electronic cigarettes as described in claim 2, characterized in that, The cooling agent includes one or more of (+)-isopreneol, L-menthone, isopreneol, D,L-menthone, WS-23, and (-)-menthyl acetate.

4. The method for testing the transfer behavior of cooling agents in electronic cigarettes as described in claim 1, characterized in that, The cooling agents comprise 13 types, namely L-menthone, isomenthone, (-)-menthyl acetate, (+)-isomenthyl alcohol, D,L-menthyl alcohol, piperone, WS-23, WS-27, menthyl lactate, p-menthane-3,8-diol, WS-3, menthone glycerol ketal, and WS-5.

5. The method for testing the transfer behavior of cooling agents in electronic cigarettes as described in claim 4, characterized in that, Isomenthone, L-menthone, (-)-menthyl acetate, (+)-isomenthyl alcohol, and D,L-menthyl alcohol were treated with acetophenone-D8 as internal standard, while the remaining compounds were treated with 2'2-bipyridine-D8 as internal standard.

6. The method for testing the transfer behavior of cooling agents in electronic cigarettes as described in claim 1, characterized in that, The highly polar chromatographic column is HP-INNOWAX, and the initial temperature is maintained for 1-2 minutes, followed by heating to 240-260°C and maintaining the temperature for 6-7 minutes.

7. The method for testing the transfer behavior of cooling agents in electronic cigarettes as described in any one of claims 1 to 6, characterized in that, The transfer rate is calculated using the following formula: TR2 represents the transfer rate (%) of each cooling agent from e-cigarette vaporized material to e-cigarette aerosol. C 气相 C 粒相 and C 雾化物 The concentrations, in μg / mL, of each cooling agent in the e-cigarette aerosol capture liquid, e-cigarette filter extract, and e-cigarette atomized products, respectively. V 气相 V 粒相 、 and V 雾化物 The volumes, in mL, are respectively the e-cigarette aerosol capture liquid, e-cigarette filter extract, and e-cigarette atomized extract. m 雾化物 m 弹前 and m 弹后 The quantities are, in grams, the mass of the electronic cigarette atomized material, the mass of the cartridge before inhalation, and the mass of the cartridge after inhalation.

8. A method for testing the content of cooling agent in electronic cigarette atomizers, characterized in that, Includes the following steps: S1. Add methanol and internal standard to the e-cigarette vaporized material for extraction to obtain e-cigarette vaporized material extract; S2. Gas chromatography-mass spectrometry analysis of the e-cigarette vapor extract to determine the content of the cooling agent; the cooling agent contains at least WS-3 and menthone glycerol ketal; the gas chromatography-mass spectrometry analysis conditions are: a highly polar chromatographic column; the temperature program is: an initial temperature of 55~65℃, followed by a temperature increase of 10~20℃ / min to 240~260℃ and holding.

9. The method for testing the content of cooling agent in electronic cigarette vapor as described in claim 8, characterized in that, The cooling agent includes one or more of (+)-isopreneol, L-menthone, isomenthone, D,L-menthone, WS-23, (-)-menthyl acetate, piperone, p-menthane-3,8-diol, WS-27, menthyl lactate, and WS-5.

10. The method for testing the content of cooling agent in electronic atomized products as described in claim 8 or 9, characterized in that, The highly polar chromatographic column is HP-INNOWAX, and the initial temperature is maintained for 1-2 minutes, followed by heating to 240-260°C and maintaining the temperature for 6-7 minutes.

11. A method for testing the content of cooling agent in electronic cigarette aerosol, characterized in that, Includes the following steps: a) Inhale electronic cigarettes and collect them using methanol traps and filter traps connected in series. Mix the solution in the methanol traps with the internal standard to obtain the aerosol collection liquid. Methanol and internal standard were added to the precipitate of the filter trap for extraction to obtain the filter extract. b) The content of cooling agent in the aerosol trap and filter extract was tested using the same gas chromatography-mass spectrometry (GC-MS) analysis conditions; the cooling agent contained at least WS-3 and menthone glycerol ketal; the GC-MS analysis conditions were: a highly polar column; the temperature program was: an initial temperature of 55-65°C, followed by a temperature increase of 10-20°C / min to 240-260°C and a holding temperature.

12. The method for testing the content of cooling agent in electronic cigarette aerosol as described in claim 11, characterized in that, The cooling agent includes one or more of (+)-isopreneol, L-menthone, isomenthone, D,L-menthone, WS-23, (-)-menthyl acetate, piperone, p-menthane-3,8-diol, WS-27, menthyl lactate, and WS-5.

13. The method for testing the content of cooling agent in electronic cigarette aerosol as described in claim 11 or 12, characterized in that, The highly polar chromatographic column is HP-INNOWAX, and the initial temperature is maintained for 1-2 minutes, followed by heating to 240-260°C and maintaining the temperature for 6-7 minutes.

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