Method for simultaneously determining contents of nicotine, water, 1, 2-propylene glycol and glycerol and application thereof

Abstract

The invention discloses a method for simultaneously determining the content of nicotine, water, 1, 2-propylene glycol and glycerol and application of the method, and the method comprises the following steps: S1, taking a sample to be detected, and extracting to obtain extract liquor; s2, taking the extract liquor, and carrying out quantitative analysis on nicotine, water, 1, 2-propylene glycol and glycerol in the to-be-detected sample by adopting a gas chromatographic method, wherein the gas chromatography method comprises the following steps: taking nitrogen as carrier gas to bring the extract liquor into a capillary chromatographic column for separation, and dividing the separated gas into two paths, one path is subjected to FID detection, and the other path is subjected to TCD detection. According to the method, double detectors are adopted for detection, and nicotine, water, 1, 2-propylene glycol and glycerol can be accurately, efficiently and synchronously detected and analyzed through one-time sample introduction, so that time and labor are saved; the method is high in quantitative accuracy, good in precision, high in recovery rate and high in sensitivity, is particularly suitable for detection and analysis of large-batch samples, and has a good application prospect in the field of tobacco product quality control.

Description

Technical Field

[0001] The invention relates to the field of detection technology, and in particular to a method for simultaneously determining the contents of nicotine, water, 1,2-propylene glycol and glycerol and an application thereof. Background Art

[0002] As a kind of addiction, tobacco products can relieve people's mental stress and tension, and are widely loved by people. Traditional tobacco products produce smoke through high-temperature combustion, and smokers inhale the smoke produced. However, tobacco produces a variety of harmful components during the combustion process, which has a great impact on people's health. Therefore, in recent years, with consumers' attention to smoking and health issues, novel tobacco products have become more and more popular. Novel tobacco products refer to tobacco products that contain tobacco or can produce smoke and taste, can bring people the pleasure of smoking, and meet physiological needs, but do not belong to other categories of tobacco products such as cigarettes, self-rolling tobacco, pipe tobacco, hookah, cigars, cigarillos, chewing tobacco, snuff and oral tobacco products. They mainly include electronic cigarettes (using electronic equipment to simulate traditional cigarette smoke, atomize nicotine-containing solutions, and provide smokers with similar satisfaction to smoking traditional cigarettes), low-temperature cigarettes (i.e., heat-not-burn cigarettes, which are smoked by heating non-burning tobacco products, and the aroma components in the cigarettes are vaporized to produce smoke to meet people's smoking needs), etc.

[0003] Nicotine, also known as nicotine, is the main physiologically active substance in tobacco products. Its content in tobacco products directly affects the physiological satisfaction and irritation of tobacco products. Therefore, accurate and rapid determination of the nicotine content in tobacco products is of great significance to the research and development of tobacco products and the control of product quality. Moisture content is another important quality indicator of tobacco products, which directly affects the sensory quality of the products. Therefore, the moisture content in tobacco products has always been another important issue of concern to tobacco product developers. In addition, 1,2-propylene glycol and glycerol (propylene glycol) are widely used solvents or additives in new tobacco products, which can help the flavor components evaporate from tobacco materials. At the same time, propylene glycol and 1,2-propylene glycol also have strong hygroscopicity, so they also have a certain impact on the moisture content of tobacco products. Based on this, in addition to nicotine and moisture monitoring, new tobacco products also need to monitor the content of propylene glycol and 1,2-propylene glycol to achieve quality control of tobacco products.

[0004] At present, the current national standard "Gas Chromatography for the Determination of Nicotine, Propylene Glycol and Glycerol in Electronic Cigarette Liquids" GBT41701-2022 guides the analysis of the nicotine, propylene glycol and glycerol content in electronic cigarette liquids by a gas chromatograph with a hydrogen flame ionization detector (GC-FID). However, since water has no response on the hydrogen flame ionization detector (FID), it is necessary to classify the water separately, which makes the detection process more time-consuming and labor-intensive, and the detection cost is high. When nitrogen is used as a carrier gas and a gas chromatography is combined with a thermal conductivity detector (TCD), although four components can be detected, the detection sensitivity is extremely low. Some related technologies disclose the use of helium as a carrier gas, and the combination of gas chromatography and a thermal conductivity detector (TCD) to achieve the simultaneous detection of water and nicotine, propylene glycol and glycerol. However, due to the large amount of helium used in the test process and the high price of helium, for factories that need to test large quantities of samples, the economic cost is too high and it is difficult to meet production needs.

[0005] Based on this, it is of great significance to develop a low-cost method that can simultaneously determine nicotine, water, 1,2-propylene glycol and glycerol. Summary of the invention

[0006] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a method for simultaneously determining the contents of nicotine, water, 1,2-propylene glycol and glycerol, which can simultaneously determine the contents of nicotine, water, 1,2-propylene glycol and glycerol without using helium as a carrier gas and has low cost.

[0007] The invention also proposes the application of the method.

[0008] According to one aspect of the present invention, a method for simultaneously determining the contents of nicotine, water, 1,2-propylene glycol and glycerol is provided, comprising the following steps:

[0009] S1. Take the sample to be tested, extract it, and obtain the extract;

[0010] S2. Taking the extract, and using gas chromatography to perform quantitative analysis on nicotine, water, 1,2-propylene glycol and glycerol in the sample to be tested;

[0011] Wherein, the sample to be tested is a tobacco product, and the gas chromatography method comprises the following steps:

[0012] The extract is carried into a capillary chromatographic column using nitrogen as a carrier gas for separation. The separated gas is split into two paths, one path is detected by FID, and the other path is detected by TCD.

[0013] According to a preferred embodiment of the present invention, at least the following beneficial effects are achieved: the method of the present invention adopts gas chromatography-hydrogen flame ionization detector (FID)-thermal conductivity detector (TCD) dual detector detection, and the water content is detected by TCD while 1,2-propylene glycol and glycerol are determined by FID. With one injection, accurate and efficient simultaneous detection and analysis of the four components of nicotine, water, 1,2-propylene glycol and glycerol can be achieved, saving time and effort; at the same time, nitrogen can be used as a carrier gas, which can greatly save economic costs (market reference price: nitrogen is about 200 yuan / bottle, helium is about 3500 yuan / bottle, and the cost of the method of the present invention is only 5.7% of the traditional method (helium as carrier gas, TCD as detector)). When nitrogen is used as a carrier gas and TCD as a detector, the detection sensitivity is extremely low, and when helium is used, although it has a higher sensitivity, the cost is too high. The method of the present invention cleverly combines FID-TCD with GC, uses nitrogen as a carrier gas, and ensures higher sensitivity and accuracy at a lower cost. This method has high quantitative accuracy, good precision, high recovery rate and high sensitivity (especially for nicotine), and is particularly suitable for detection and analysis of large batches of samples.

[0014] In some embodiments of the present invention, the sample to be tested is a novel tobacco product.

[0015] In some preferred embodiments of the present invention, the sample to be tested is at least one of electronic cigarette liquid or heat-not-burn cigarette smoke.

[0016] In some preferred embodiments of the present invention, if the sample to be tested is heat-not-burn cigarette smoke, the sample to be tested is captured by the following operations: taking a cigarette sample for balancing treatment, inhaling, collecting total particulate matter through a Cambridge filter, and placing the Cambridge filter after collecting the total particulate matter in an extraction device for extraction.

[0017] In some preferred embodiments of the present invention, the specific operation of the capture process is: first preheat the smoking machine, set the suction parameters, calibrate the suction capacity, place the clean and uncontaminated Cambridge filter in the collector of the smoking machine to capture the smoke, insert the heat-not-burn cigarette sample to be tested into the corresponding interface to start the suction operation (during the operation, it is necessary to ensure that the heat-not-burn cigarette matching smoking utensils can work normally during the suction process). After the capture is completed, the Cambridge filter is quickly taken out, and the collector is wiped with a 1 / 4 Cambridge filter, and the wiped Cambridge filter and the captured Cambridge filter are placed in an extraction device for extraction.

[0018] In some preferred embodiments of the present invention, the specific operation of the cigarette sample balancing treatment is: placing the cigarette sample to be tested in a constant temperature and humidity environment with a temperature of 22±1°C and a humidity of 60±3(%) for balancing adjustment, and the balancing time is more than 48 hours and no more than 10 days.

[0019] In some preferred embodiments of the present invention, the extraction operation is specifically: mixing the sample to be tested with the extractant and shaking. Sufficient shaking is sufficient, and the operation is simple.

[0020] In some preferred embodiments of the present invention, the oscillation speed is 180 r / min to 200 r / min.

[0021] In some preferred embodiments of the present invention, the oscillation time is 20 to 60 minutes. The extraction time of the method of the present invention is short, which further improves the detection efficiency of the entire method. For the e-cigarette liquid sample to be tested, oscillation for 20 minutes is sufficient, while for heat-not-burn cigarettes, the oscillation time needs to be slightly extended.

[0022] In some embodiments of the present invention, the extraction temperature is 25±2°C.

[0023] In some embodiments of the present invention, the extraction temperature is 25±2° C. Extraction at room temperature is sufficient, and the operation is simple.

[0024] In some embodiments of the present invention, the extraction agent used in the extraction is at least one of methanol or isopropanol.

[0025] In some embodiments of the present invention, the extract contains an internal standard substance. The internal standard substance can be directly added to the extractant so that the obtained extract contains the internal standard substance, which is easy to operate.

[0026] In some preferred embodiments of the present invention, if the sample to be tested is heat-not-burn cigarette smoke, the step S1 further includes filtering the extract after extraction.

[0027] In some embodiments of the present invention, the quantitative analysis includes the step of using an internal standard substance standard curve method to quantitatively calculate the content of the target substance in the sample. The content analysis by the internal standard substance method is accurate and reliable.

[0028] In some embodiments of the present invention, the internal standard substance standard curve method prepares a series of standard working solutions containing an internal standard substance and a target substance, and establishes a standard working curve with the peak area ratio of the target substance to the internal standard substance in the standard working solution as the ordinate and the concentration ratio of the target substance to the internal standard substance in the standard working solution as the abscissa; the measured peak area ratio of the target substance to the internal standard substance in the sample to be tested is substituted into the standard working curve, the concentration ratio of the target substance to the internal standard substance in the sample to be tested is calculated, and then the content of each target substance in the sample to be tested is further calculated.

[0029] In some embodiments of the present invention, the concentration range of 1,2-propylene glycol in the series of standard working solutions is 0-1026 mg / L, the concentration range of nicotine is 0-1026 mg / L, the concentration range of glycerol is 0-8901 mg / L, and the concentration range of water is 0-6093 mg / L. The method of the present invention has a wide linear range and can be used for the analysis of samples to be tested in a wide concentration range.

[0030] In some preferred embodiments of the present invention, the internal standard substance includes 1,4-butanediol and n-heptadecane. The quantitative result is more accurate when double internal standard substances are used for quantification, 1,4-butanediol is used for quantification of water, and n-heptadecane is used for quantification of nicotine, 1,2-propylene glycol and glycerol.

[0031] In some embodiments of the present invention, the separated gas is divided into two paths through a splitter assembly, the splitter assembly includes a splitter and two uncoated capillary columns, the splitter includes a splitter main pipe and two splitter branches connected to the splitter main pipe, wherein the splitter main pipe is connected to the end of the capillary chromatographic column, and each of the splitter branches is connected to an uncoated capillary column. Two hollow capillary columns are connected through a "Y"-shaped splitter, and the two gas flows are respectively introduced into the detector for detection through the hollow capillary column, so that only one injection and one separation are required to achieve efficient detection by two detectors at the same time, saving time and effort.

[0032] In some embodiments of the present invention, the specifications of the uncoated capillary column are: column length: 0.5-1.0 m, inner diameter: 200-250 μm.

[0033] In some embodiments of the present invention, the separated gas is evenly divided into two paths. The separated gas can be evenly divided into two paths by two uncoated hollow capillary columns with the same inner diameter.

[0034] In some embodiments of the present invention, the stationary phase of the capillary chromatographic column is bonded / cross-linked polyethylene glycol. The detection and analysis by the method of the present invention has a short analysis time.

[0035] In some preferred embodiments of the present invention, the parameters of the capillary chromatographic column include:

[0036] Column length: 30m, inner diameter: 320μm, film thickness: 0.25~0.5μm.

[0037] In some preferred embodiments of the present invention, the capillary chromatographic column is a HP-INNOWAX capillary column.

[0038] In some embodiments of the present invention, the parameter setting of the gas chromatography method includes:

[0039] Carrier gas pressure control mode: constant flow mode, carrier gas flow rate 1.5~2mL / min.

[0040] In some embodiments of the present invention, the parameter setting of the gas chromatography method includes:

[0041] Inlet temperature: 250~260℃.

[0042] In some embodiments of the present invention, the parameter setting of the gas chromatography method includes:

[0043] Injection mode: split injection, injection split ratio 5:1~30:1.

[0044] In some embodiments of the present invention, the parameter setting of the gas chromatography method includes:

[0045] Injection method: automatic injection.

[0046] In some embodiments of the present invention, the parameter setting of the gas chromatography method includes:

[0047] Injection volume: 1.0~1.2μL.

[0048] In some embodiments of the present invention, the parameter setting of the gas chromatography method includes:

[0049] Temperature program: initial column temperature 50-70°C, maintain for 3-5 minutes, increase to 180-200°C at 8-15°C / min, then increase to 240-250°C at 20-30°C / min, and maintain for 2-5 minutes.

[0050] In some embodiments of the present invention, the parameter setting of the gas chromatography method includes:

[0051] TCD detector: detector temperature: 250-260°C, reference flow rate: 15-25 mL / min, tail gas flow rate: 9-12 mL / min, negative polarity: on;

[0052] FID detector: detector temperature: 250-260°C, air flow rate: 350-450 mL / min, hydrogen flow rate: 30-40 mL / min, tail gas flow rate: 20-25 mL / min.

[0053] According to another aspect of the present invention, a method for quality control of tobacco products is proposed, comprising detecting the contents of nicotine, water, 1,2-propylene glycol and glycerol in the tobacco products by the above method, and determining whether the quality of the tobacco products meets the standards based on the detection results.

[0054] According to a preferred embodiment of the present invention, the quality control method of tobacco products has at least the following beneficial effects: based on the relationship between the target content and the threshold value, it is determined whether the quality of the tobacco products meets the standard, the detection process is simple and easy to operate, economical and efficient, and the measurement results are accurate and reliable. The quality control of tobacco products can be quickly and effectively achieved through the method of the present invention, which provides a strong guarantee for the quality control in the production of tobacco products. At the same time, the present invention can realize the simultaneous detection of four target components by combining FID, TCD and GC, and by using nitrogen as a carrier gas, it can achieve the same sensitivity and detection accuracy as using helium, which greatly saves production costs while ensuring the detection effect, and has good industrial application prospects.

[0055] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0057] Figure 1 Schematic diagram of the structure of the device used in the gas chromatography method in the embodiment of the present invention;

[0058] Figure 2 is the standard working curve of water measured in Example 1 of the present invention;

[0059] Figure 3 is the standard working curve of nicotine measured in Example 1 of the present invention;

[0060] Figure 4 is the standard working curve of 1,2-propylene glycol measured in Example 1 of the present invention;

[0061] Figure 5 is the standard working curve of glycerol measured in Example 1 of the present invention;

[0062] Figure 6 is the chromatogram of sample 1 recorded by FID in Example 1 of the present invention;

[0063] Figure 7 is the chromatogram of sample 1 recorded by TCD in Example 1 of the present invention;

[0064] Figure 8 is the standard working curve of water measured in Example 2 of the present invention;

[0065] Fig. 9 is the standard working curve of nicotine measured in Example 2 of the present invention;

[0066] Fig.10is the standard working curve of 1,2-propylene glycol measured in Example 2 of the present invention;

[0067] Fig.11 is the standard working curve of glycerol measured in Example 2 of the present invention;

[0068] Fig.12 is the chromatogram of sample 1 recorded by FID in Example 2 of the present invention;

[0069] Fig.13 It is the chromatogram of sample 1 recorded by TCD in Example 2 of the present invention. DETAILED DESCRIPTION

[0070] The following will be combined with the embodiments to clearly and completely describe the concept of the present invention and the technical effects produced, so as to fully understand the purpose, characteristics and effects of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, other embodiments obtained by technicians in this field without creative work are all within the scope of protection of the present invention. The test methods used in the embodiments are conventional methods unless otherwise specified; the materials, reagents, etc. used, unless otherwise specified, can be reagents and materials obtained from commercial channels. Unless otherwise specified, the same parameter in each embodiment has the same value. The embodiments described below are exemplary and are only used to explain the present invention, and cannot be understood as limitations on the present invention.

[0071] Example 1

[0072] This embodiment provides a method for simultaneously determining the contents of nicotine, water, 1,2-propylene glycol and glycerol in electronic cigarette liquid. The specific process is as follows:

[0073] 1) Draw a standard curve

[0074] Use an electronic balance (METTLER TOLEDO, measuring range 0-220g, accuracy 0.1mg) to accurately weigh the target substances: 677.0mg (accurate to 0.1mg) of ultrapure water, 114.0mg (accurate to 0.1mg) of 1,2-propylene glycol standard substance, 129.0mg (accurate to 0.1mg) of nicotine standard substance, 989.0mg (accurate to 0.1mg) of glycerol standard substance and internal standard substances: 4.0mg (accurate to 0.1mg) of heptadecane standard substance and 408.8mg (accurate to 0.1mg) of 1,4-butanediol standard substance, put them together in a 100mL volumetric flask, make up to 100mL of the volumetric flask with methanol solution, shake well and prepare before use. Ultrapure water was prepared by taking water from an ultrapure water machine (UPH-IV-20TNP) (the requirements of grade 3 water in GB / T 6682), and other standard substances were purchased from the market with a purity of not less than 99.9%.

[0075] Accurately weigh the internal standard substances: 4.0 mg (accurate to 0.1 mg) of heptadecane standard substance and 408.8 mg (accurate to 0.1 mg) of 1,4-butanediol standard substance, place them in a 100-mL volumetric flask, make up to 100-mL volumetric flask with methanol solution, shake well, and prepare before use.

[0076] Accurately measure 0mL, 0.1mL, 0.2mL, 0.5mL, 1.0mL, 3.0mL, 5.0mL, 7.0mL, and 9.0mL of the above target solution into 9 10mL volumetric flasks in turn, make up to volume with methanol solution containing internal standard substances (heptadecane concentration 40 mg / L, 1,4-butanediol concentration 4088 mg / L), shake well, and prepare as standard working solution before use.

[0077] The standard working solution after the above-mentioned operation is subjected to gas chromatography to measure the peak areas of the internal standard substance and the target substance in the standard working solution.

[0078] The gas chromatography was carried out by gas chromatography-TCD-FID dual detector (Agilent 8890), specifically, as Figure 1 As shown, the sample is injected through an automatic sampler, and after gasification, it is separated by a capillary column (HP-INNOWAX, 30m×320μm×0.25μm) in a gas chromatogram. A "Y" type splitter is installed at the end of the column, and the sample outlet of the splitter is connected to two hollow (uncoated) capillary columns (0.5m*250μm) of the same specification. The two hollow capillary columns are respectively connected to a thermal conductivity detector (TCD) and a hydrogen flame ionization detector (FID), and a single injection is achieved to obtain the TCD detector chromatogram and the FID detector chromatogram of the sample. The dual detectors are installed in parallel through the hollow capillary column.

[0079] The specific conditions of gas chromatography are as follows: carrier gas: nitrogen, pressure control mode: constant flow mode, flow rate 2 mL / min, injection port temperature: 250°C, injection mode: split injection, split ratio 5:1, injection volume: 1 μL, chromatographic column: HP-INNOWAX capillary column (30 m×320 μm×0.25 μm), heating program: initial column temperature 60°C, hold for 3.8 min, heat to 190°C at 10°C / min, then heat to 240°C at 30°C / min, hold for 2 min; TCD detector: detector temperature: 260°C, reference flow: 20 mL / min, tail flow: 9 mL / min, negative polarity: on; FID detector: detector temperature: 260°C, air flow: 400 mL / min, hydrogen flow: 30 mL / min, tail flow: 20 mL / min.

[0080] The retention times and internal standard substance information of the four target substances measured were water: 3.567min; 1,2-propylene glycol: 11.892min; nicotine: 15.026min; propylene glycol: 18.622min.

[0081] The standard working curve is drawn with the peak area ratio of the target substance to the internal standard substance in the standard working solution (relative response) as the ordinate and the concentration ratio of the target substance to the internal standard substance in the standard working solution (relative content) as the abscissa. Figures 2 to 5 As shown in the figure, the internal standard substance for water is 1,4-butanediol; the internal standard substances for other targets are heptadecane.

[0082] The standard solution with the minimum concentration was injected 7 times, and the standard deviation of the determination result was calculated. The detection limit was calculated according to the formula MDL=t(n-1, 0.99)×SD; the quantitative limit was calculated as 4 times the detection limit.

[0083] The linear regression analysis of the standard working curve and the calculation results of the detection limit and quantification limit are shown in Table 1.

[0084] Table 1

[0085]

[0086] Note: When n=7, t(n-1, 0.99)=3.143.

[0087] It can be seen from Table 1 that the standard curves of water, 1,2-propylene glycol, nicotine and glycerol have good linearity, and r is all above 0.9999, indicating that the method of the present invention has high accuracy; the detection limit and quantification limit of the four components are between 0.001 and 0.012 mg / mL and 0.004 and 0.048 mg / mL, respectively, indicating that the method of the present invention has high sensitivity and can better meet the detection needs of electronic cigarette liquid water, 1,2-propylene glycol, nicotine and glycerol.

[0088] 2) Detection of samples to be tested

[0089] Weigh 0.1g of electronic cigarette liquid produced by a factory (recorded as sample 1, to 0.001g), place it in a 50mL stoppered conical flask, add 10mL of isopropanol (HPLC grade) solution containing internal standard substances (heptadecane concentration 40mg / L, 1,4-butanediol concentration 4088mg / L), and oscillate at 200r / min for 20min at 25°C using a constant temperature oscillator (Guohua, SHA-C) to mix. Take 1mL of the sample solution to be tested after the above operation and dilute it 100 times. The peak area of ​​the internal standard substance and the target substance in the sample solution to be tested is measured by gas chromatography under exactly the same conditions as the above operation. The chromatogram results recorded by FID and TCD are as follows: Figures 6-7 shown.

[0090] As can be seen from the figure, the combination of the two detectors can make the four target components have high response values ​​and the detected target components have good peak shapes, and the separation between adjacent peaks can better meet the quantitative requirements. In addition, there is no overlap between the peak shapes of the internal standard substance and the target substance, indicating that heptadecane and 1,4-butanediol are suitable as internal standard substances. When nitrogen is used as the carrier gas, nicotine, 1,2-propylene glycol, glycerol, etc. have almost no response or only a weak response on the TCD detector.

[0091] Substitute the peak area ratio of the target substance and the internal standard substance obtained by the determination into the standard working curve obtained by the above operation, and calculate the concentration ratio of the target substance and the internal standard substance in the sample solution to be tested. The concentration of the target substance in the sample solution to be tested is converted by multiplying the concentration ratio by the concentration of the internal standard substance, and then the mass of the target substance in the weighed electronic cigarette liquid is converted according to the product of the concentration of the target substance in the sample solution to be tested and the volume, and the ratio of the two is calculated to obtain the relative content of the target substance in the electronic cigarette liquid.

[0092] Calculation showed that the contents of water, 1,2-propylene glycol, nicotine and glycerin in sample 1 were 18.8 mg / g, 523.1 mg / g, 10.0 mg / g and 401.8 mg / g, respectively.

[0093] In order to verify the reliability of the method, a spike experiment was carried out. The specific process is as follows:

[0094] Take the above sample 1 (3 portions), add water, 1,2-propylene glycol, glycerol and nicotine standards at low, medium and high levels, and measure 7 times in parallel for each addition level. The samples were pretreated and chromatographically analyzed according to the above method, and the recovery rate and relative standard deviation (RSD) were calculated based on the original content and the addition amount. The calculation results are shown in Table 2.

[0095] Table 2

[0096]

[0097]

[0098] As can be seen from Table 2, the spiked recoveries of water, 1,2-propylene glycol, glycerol and nicotine are 96.5-105%, 100-105%, 100-105% and 98.7-103%, respectively, and the relative standard deviations (RSD%) are 1.75-3.91%, 0.17-2.68%, 0.12-1.71% and 0.24-1.39%, respectively. This shows that the method of the embodiment of the present invention has good precision and high recovery rate, and is suitable for the quantitative analysis of water, 1,2-propylene glycol, glycerol and nicotine in electronic cigarette extract.

[0099] The above method was used to test e-cigarette liquid samples 2 to 11 with known component information (the levels of four components in the samples were determined by other laboratories using the national standard method, and samples 7 to 11 did not contain nicotine). The results showed that the test results were completely consistent with the known content information. The specific test results are shown in Table 3 below.

[0100] Table 3

[0101]

[0102] The above method was used to determine the target substance content of other batches of e-cigarette liquid. At the same time, the samples from the same source were commissioned to an external laboratory for testing with reference to GB / T 41701-2022. The test results and the relative deviation calculation results of the two methods are shown in Table 4 below:

[0103] Table 4

[0104]

[0105]

[0106] It can be seen from Table 4 that the relative deviations of the water content, 1,2-propylene glycol, nicotine and glycerol content of the same type of e-liquid determined by the method of the embodiment of the present invention and the external laboratory are 0.92%-1.49%, 1.22%-2.32%, 0.16%-0.35% and 0.32%-0.53%, respectively; the variability of the test results is less than 2.5%, which can meet the requirements for rapid detection of the main components of electronic cigarette liquid and can be used for quality control of the production process of heat-not-burn cigarettes.

[0107] Example 2

[0108] This example provides a method for simultaneously determining the contents of nicotine, water, 1,2-propylene glycol and glycerol in a heat-not-burn (HNB) cigarette aerosol. The specific process is as follows:

[0109] 1) Draw a standard curve

[0110] Use an electronic balance (METTLER TOLEDO, measuring range 0-220g, accuracy 0.1mg) to accurately weigh the target substances: 618.0mg (accurate to 0.1mg) of ultrapure water, 33.0mg (accurate to 0.1mg) of 1,2-propylene glycol standard substance, 112.0mg (accurate to 0.1mg) of nicotine standard substance, 329.0mg (accurate to 0.1mg) of glycerol standard substance and internal standard substances: 4.0mg (accurate to 0.1mg) of heptadecane standard substance and 408.8mg (accurate to 0.1mg) of 1,4-butanediol standard substance, put them together in a 100mL volumetric flask, make up to 100mL of the volumetric flask with methanol solution, shake well and prepare before use. Ultrapure water was prepared by taking water from an ultrapure water machine (UPH-IV-20TNP) (the requirements of grade 3 water in GB / T 6682), and other standard substances were purchased from the market with a purity of not less than 99.9%.

[0111] Accurately weigh the internal standard substances: 4.0 mg (accurate to 0.1 mg) of heptadecane standard substance and 408.8 mg (accurate to 0.1 mg) of 1,4-butanediol standard substance, place them in a 100-mL volumetric flask, make up to 100-mL volumetric flask with methanol solution, shake well, and prepare before use.

[0112] Accurately measure 0mL, 0.1mL, 0.2mL, 0.5mL, 1.0mL, 3.0mL, 5.0mL, 7.0mL, and 9.0mL of the above target solution into 9 10mL volumetric flasks in turn, make up to volume with methanol solution containing internal standard substances (heptadecane concentration 40 mg / L, 1,4-butanediol concentration 4088 mg / L), shake well, and prepare as standard working solution before use.

[0113] The standard working solution after the above-mentioned operation treatment was subjected to gas chromatography (the conditions of the gas chromatography were the same as those in Example 1) to measure the peak areas of the internal standard substance and the target substance in the standard working solution.

[0114] The retention times and internal standard substance information of the four target substances measured were water: 3.567min; 1,2-propylene glycol: 11.892min; nicotine: 15.028min; propylene glycol: 18.622min.

[0115] The standard working curve is drawn with the peak area ratio of the target substance to the internal standard substance in the standard working solution (relative response) as the ordinate and the concentration ratio of the target substance to the internal standard substance in the standard working solution (relative content) as the abscissa. Figures 8 to 11 As shown in the figure, the internal standard substance for water is 1,4-butanediol; the internal standard substances for other targets are heptadecane.

[0116] The standard solution with the minimum concentration was injected 7 times, and the standard deviation of the determination result was calculated. The detection limit was calculated according to the formula MDL=t(n-1, 0.99)×SD; the quantitative limit was calculated as 4 times the detection limit.

[0117] The linear regression analysis of the standard working curve and the calculation results of the detection limit and quantification limit are shown in Table 5 below.

[0118] Table 5

[0119] Test items Linear concentration range (mg / mL) Correlation coefficient r Detection limit (mg / mL) Limit of quantitation (mg / mL) water 0～5.562 0.9995 0.012 0.048 Propylene glycol 0～0.297 0.9999 0.001 0.004 Nicotine 0～1.008 0.9999 0.001 0.004 Glycerol 0～2.961 0.9997 0.003 0.012

[0120] Note: When n=7, t(n-1, 0.99)=3.143.

[0121] It can be seen from Table 5 that the standard curves of water, 1,2-propylene glycol, nicotine and glycerol have good linearity, and r is between 0.9995 and 0.9999, indicating that the method of the present invention has high accuracy; the detection limit and quantification limit of the four components are between 0.001 and 0.012 mg / mL and 0.004 and 0.048 mg / mL, respectively, indicating that the method of the present invention has high sensitivity and can better meet the detection needs of electronic cigarette liquid water, 1,2-propylene glycol, nicotine and glycerol.

[0122] 2) Detection of samples to be tested

[0123] Heat-not-burn cigarette sample conditioning: Place the cigarette sample to be tested in a constant temperature and humidity environment with a temperature of 22±1°C and a humidity of 60±3(%) for equilibrium conditioning. The equilibrium time is 48 hours and no more than 10 days.

[0124] Preparation of the smoking machine: First turn on the power of the machine and preheat it for 20 minutes. Then, according to the smoking parameter requirements of the Canadian deep smoking mode (HCI) (smoking curve: bell-shaped, smoking capacity: 55mL, smoking time: 2s, smoking interval: 30s, number of puffs: 8 puffs), set the corresponding smoking machine parameters and calibrate the smoking capacity of the smoking machine.

[0125] Capture of total particulate matter in mainstream smoke of heat-not-burn cigarettes: After the preparation work for debugging the smoking machine is completed, a clean and uncontaminated Cambridge filter (diameter 44 mm) is installed in the collector, and the heat-not-burn cigarette sample (recorded as sample I) is inserted into the interface to start the smoking operation. During the operation, it is necessary to ensure that the supporting smoking utensils of the heat-not-burn cigarette can work normally during the smoking process. Six groups of parallel experiments were conducted, and each Cambridge filter captured the total particulate matter in the mainstream smoke of 2 cigarettes.

[0126] Extraction: Quickly remove the Cambridge filter from the trap, place it in a 50mL stoppered conical flask, then wipe the trap with 1 / 4 Cambridge filter, and place the wiped Cambridge filter in the same stoppered conical flask. Add 25mL of isopropanol (HPLC grade) solution containing internal standard substances (heptadecane concentration 40mg / L, 1,4-butanediol concentration 4088mg / L), and oscillate at 200r / min for 20min at 25°C using a constant temperature oscillator (Guohua, SHA-C) to mix. Take 1mL of the sample solution to be tested after the above operation, and measure the peak areas of the internal standard substance and the target substance in the sample solution to be tested by gas chromatography under exactly the same conditions as the above operation. The chromatogram results recorded by FID and TCD are as shown below. Figures 12-13 shown.

[0127] As can be seen from the figure, the combination of the two detectors can make the four target components have high response values ​​and the detected target components have good peak shapes, and the separation between adjacent peaks can better meet the quantitative requirements. In addition, there is no overlap between the peak shapes of the internal standard substance and the target substance, indicating that heptadecane and 1,4-butanediol are suitable as internal standard substances. When nitrogen is used as the carrier gas, nicotine, 1,2-propylene glycol, glycerol, etc. have almost no response or only a weak response on the TCD detector.

[0128] Substitute the peak area ratio of the target substance and the internal standard substance obtained by the determination into the standard working curve obtained by the above operation, and calculate the concentration ratio of the target substance and the internal standard substance in the sample solution to be tested. The concentration of the target substance in the sample solution to be tested is converted by multiplying the concentration ratio by the concentration of the internal standard substance, and then the mass of the target substance in the weighed electronic cigarette liquid is converted according to the product of the concentration of the target substance in the sample solution to be tested and the volume, and the ratio of the two is calculated to obtain the relative content of the target substance in the electronic cigarette liquid.

[0129] Calculation showed that the contents of water, 1,2-propylene glycol, nicotine and glycerol in sample I were 22.12±0.10 mg / g, 0.25±0.02 mg / g, 1.00±0.04 mg / g and 3.24±0.30 mg / g, respectively.

[0130] In order to verify the feasibility of the method, a spike experiment was carried out. The specific process is as follows:

[0131] Take the above sample I (3 portions), add water, 1,2-propylene glycol, glycerol and nicotine standards at low, medium and high levels, and measure 7 times in parallel for each addition level. The samples were pre-treated and chromatographically analyzed according to the above method, and the recovery rate and relative standard deviation (RSD) were calculated based on the original content and the addition amount. The calculation results are shown in Table 6 below.

[0132] Table 6

[0133]

[0134] It can be seen from Table 6 that the average spiked recoveries of the four components are between 95.8% and 106%, and the average relative standard deviations (RSD%) are between 0.4% and 5.62%, which can better meet the detection requirements of HNB water, 1,2-propylene glycol, nicotine, and glycerol.

[0135] The above method was used to detect heat-not-burn cigarette samples II to VIII of different series or different utensils (among which, sample II and sample I are from different heat-not-burn cigarette series and have different utensils; sample III and sample II are from the same heat-not-burn cigarette series and have different utensils; sample IV and sample I are from different heat-not-burn cigarette brands and have different utensils; sample V and sample III are from different heat-not-burn cigarette series and have the same utensils; sample VI and sample I are from the same heat-not-burn cigarette brand and have different utensils; sample VII and sample VI are from the same heat-not-burn cigarette series and have different utensils; sample VIII and sample VI are from the same heat-not-burn cigarette series and have different utensils), and the results are shown in Table 7 below.

[0136] Table 7

[0137]

[0138]

[0139] It can be seen from Table 7 that the method of the embodiment of the present invention can accurately and effectively detect heat-not-burn cigarette samples of different series and different utensils, and the method is accurate and reliable.

[0140] Sample I and other samples IX to XI (wherein, sample IX and sample I are from the same heat-not-burn cigarette series, but with different apparatuses; sample X and sample I are from different heat-not-burn cigarette series, but with different apparatuses; sample XI and sample X are from the same heat-not-burn cigarette series, but with different apparatuses) were subjected to target substance content determination using the above method. At the same time, samples from the same source were commissioned to an external laboratory for testing with reference to GB / T 23355-2009GB / T 23203.1-2013YC / T 243-2008. The test results and the relative deviation calculation results of the two methods are shown in Table 8 below:

[0141] Table 8

[0142] Sample No. Water (mg / cig) Propylene glycol (mg / cig) Nicotine (mg / cig) Glycerol (mg / cig) Sample I 22.12±0.10 0.25±0.02 1.00±0.04 3.24±0.30 National Standard Method-Sample I 21.70±0.52 0.25±0.02 0.99±0.05 3.22±0.31 Sample IX 20.81±0.99 0.26±0.02 1.03±0.06 3.24±0.25 National Standard Method-Sample IX 20.63±1.28 0.26±0.02 1.02±0.06 3.21±0.37 Sample X 25.33±3.15 0.32±0.02 1.31±0.06 4.63±0.42 National Standard Method-Sample X 24.84±1.75 0.32±0.02 1.30±0.07 4.57±0.41 Sample XI 23.04±0.83 0.30±0.02 1.25±0.05 4.36±0.26 National Standard Method-Sample XI 22.55±1.27 0.30±0.02 1.24±0.07 4.29±0.41

[0143] As can be seen from Table 8, the standard deviation of the same sample measured by the method of the embodiment of the present invention and the external laboratory for measuring the content of water in the e-liquid, 1,2-propylene glycol, nicotine, and glycerol is smaller or equivalent, indicating that the method of the present invention has good reliability and can be used for quality control in the production process of heat-not-burn cigarettes.

[0144] Comparative Example 1

[0145] This comparative example provides a method for simultaneously determining the contents of nicotine, water, 1,2-propylene glycol and glycerol in electronic cigarette liquid, which differs from Example 1 in that the gas chromatography method uses a gas chromatography-TCD coupling instrument and the carrier gas is helium.

[0146] Samples 12 to 15 were tested using the method of Example 1 and the above method at the same time. The results are shown in Table 9 below.

[0147] Table 9

[0148]

[0149]

[0150] It can be seen from Table 9 that the deviation of the measurement results of the same sample by the method of Example 1 and the method of Comparative Example 1 is small (within 1.5%), and Example 1 uses nitrogen as the carrier gas, which can greatly reduce the detection cost.

[0151] Comparative Example 2

[0152] This comparative example provides a method for simultaneously determining the contents of nicotine, water, 1,2-propylene glycol and glycerol in heat-not-burn cigarettes, which differs from Example 2 in that the gas chromatography method uses a gas chromatography-TCD combined instrument and the carrier gas is helium.

[0153] The contents of the four target components in samples I and IX-XI were determined by the method of Comparative Example 2, and the determination results and the determination results of Example 2 are summarized in Table 10 below.

[0154] Table 10

[0155] Sample No. Water (mg / cig) Propylene glycol (mg / cig) Nicotine (mg / cig) Glycerol (mg / cig) Example 2 - Sample I 22.12±0.10 0.25±0.02 1.00±0.04 3.24±0.30 Comparative Example 2-Sample 1 22.21±0.27 0.25±0.03 1.00±0.06 3.25±0.44 Example 2 - Sample IX 20.81±0.99 0.26±0.02 1.03±0.06 3.24±0.25 Comparative Example 2 - Sample IX 20.54±0.83 0.26±0.04 1.04±0.07 3.24±0.41 Example 2 - Sample X 25.33±3.15 0.32±0.02 1.31±0.06 4.63±0.42 Comparative Example 2 - Sample X 25.67±2.88 0.32±0.03 1.32±0.05 4.64±0.48 Example 2 - Sample XI 23.04±0.83 0.30±0.02 1.25±0.05 4.36±0.26 Comparative Example 2 - Sample XI 23.19±1.36 0.30±0.02 1.26±0.08 4.38±0.43

[0156] It can be seen from Table 10 that the results of the method in Example 2 and the method in Comparative Example 2 for the same sample are basically consistent, and Example 2 uses nitrogen as the carrier gas, which can greatly reduce the detection cost.

[0157] In summary, the gas chromatography-thermal conductivity detector (TCD)-hydrogen flame ionization detector (FID) dual detector determination method provided by the present invention is accurate, efficient, economical and can simultaneously analyze the contents of water, 1,2-propylene glycol, glycerol and nicotine in electronic cigarette liquid. The detection method has high sensitivity and the quantitative results are accurate and reliable. It can be applied to the rapid detection of the main components in various tobacco products such as electronic cigarettes and heat-not-burn cigarettes, and has good application prospects in the field of quality control of tobacco products such as electronic cigarettes and heat-not-burn cigarettes.

[0158] The embodiments of the present invention are described in detail above, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge scope of ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A method for simultaneously determining the contents of nicotine, water, 1,2-propylene glycol and glycerol, Features: The steps include: S1. Take the sample to be tested, extract it, and obtain the extract; S2. Taking the extract, and using gas chromatography to perform quantitative analysis on nicotine, water, 1,2-propylene glycol and glycerol in the sample to be tested; Wherein, the sample to be tested is a tobacco product, and the gas chromatography method comprises the following steps: The extract is carried into a capillary chromatographic column using nitrogen as a carrier gas for separation. The separated gas is split into two paths, one path is detected by FID, and the other path is detected by TCD.

2. The method for simultaneously determining the contents of nicotine, water, 1,2-propylene glycol and glycerol according to claim 1, Features: The sample to be tested is at least one of electronic cigarette liquid or heat-not-burn cigarette smoke.

3. The method for simultaneously determining the contents of nicotine, water, 1,2-propylene glycol and glycerol according to claim 1, Features: The extraction operation specifically comprises: mixing the sample to be tested with the extractant and shaking.

4. The method for simultaneously determining the contents of nicotine, water, 1,2-propylene glycol and glycerol according to claim 3, Features: The extractant is at least one of isopropanol or methanol.

5. The method for simultaneously determining the contents of nicotine, water, 1,2-propylene glycol and glycerol according to claim 1, Features: The quantitative analysis includes the step of using an internal standard substance standard curve method to quantitatively calculate the content of the target substance in the sample.

6. The method for simultaneously determining the contents of nicotine, water, 1,2-propylene glycol and glycerol according to any one of claims 1 to 5, Features: The separated gas is divided into two paths through a splitter assembly, wherein the splitter assembly includes a splitter and two uncoated capillary columns, wherein the splitter includes a splitter main pipe and two splitter branches connected to the splitter main pipe, wherein the splitter main pipe is connected to the end of the capillary chromatographic column, and each of the splitter branches is connected to an uncoated capillary column.

7. The method for simultaneously determining the contents of nicotine, water, 1,2-propylene glycol and glycerol according to any one of claims 1 to 5, Features: The stationary phase of the capillary chromatographic column is bonded / cross-linked polyethanol.

8. The method for simultaneously determining the contents of nicotine, water, 1,2-propylene glycol and glycerol according to any one of claims 1 to 5, Features: The parameter setting of the gas chromatography method includes: Carrier gas pressure control mode: constant flow mode, carrier gas flow rate 1.5~2mL / min; Inlet temperature: 250~260℃; Injection mode: split injection, injection split ratio 5:1~30:1; Injection volume: 1.0~1.2μL; Temperature program: initial column temperature 50-70°C, maintain for 3-5 minutes, increase to 180-200°C at 8-15°C / min, then increase to 240-250°C at 20-30°C / min, and maintain for 2-5 minutes.

9. The method for simultaneously determining the contents of nicotine, water, 1,2-propylene glycol and glycerol according to any one of claims 1 to 5, Features: The parameter setting of the gas chromatography method includes: TCD detector: detector temperature: 250-260°C, reference flow rate: 15-25 mL / min, tail gas flow rate: 9-12 mL / min, negative polarity: on; FID detector: detector temperature: 250-260°C, air flow rate: 350-450 mL / min, hydrogen flow rate: 30-40 mL / min, tail gas flow rate: 20-25 mL / min.

10. A method for quality control of tobacco products, Features: The method comprises detecting the contents of nicotine, water, 1,2-propylene glycol and glycerol in tobacco products by the method according to any one of claims 1 to 9, and determining whether the quality of the tobacco products meets the standards based on the detection results.

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