Method for determining content of forbidden substances in electronic cigarette liquid

Abstract

The invention discloses a method for determining the content of forbidden substances in electronic cigarette liquid. The method specifically comprises the following steps: (1) pre-treating a sample; (2) carrying out LC-MS / MS analysis conditions; and (3) determining a standard curve and quantifying. Based on the LC-MS / MS technology, the content of taurine, caffeine, cannabidiol (CBD), tetrahydrocannabinol (THC), vitamin E and vitamin E acetate in the electronic cigarette liquid can be measured at the same time, and therefore the requirements for industry supervision, product quality control and safety evaluation are met.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical analysis, and more specifically to a method for determining the content of prohibited substances in electronic cigarette liquid. Background Art

[0002] Electronic cigarettes are mainly composed of four parts: liquid (containing nicotine, flavors, solvent propylene glycol, etc.), heating system, power supply and filter. They produce aerosols with specific smells for smokers to use through heating and atomization. In a broad sense, electronic cigarettes refer to electronic nicotine delivery systems, including electronic cigarettes, hookahs, hookah pens and other forms. In a narrow sense, electronic cigarettes refer only to portable electronic cigarettes that look similar to cigarettes.

[0003] With the popularity of e-cigarettes, the analysis of the components in their atomized products has become particularly important. Taurine and caffeine are common functional additives, cannabidiol (CBD) and tetrahydrocannabinol (THC) are substances with potential pharmacological or psychoactive effects, and vitamin E and vitamin E acetate are possible additives or solvents. Their content and safety in e-cigarette liquids have attracted much attention.

[0004] However, traditional component analysis methods often have problems such as complex operation, low detection sensitivity, or inability to detect multiple components simultaneously.

[0005] Therefore, how to develop an efficient, sensitive and accurate method for determining the content of banned substances in e-cigarette liquid is an urgent problem that technicians in this field need to solve. Summary of the invention

[0006] In view of this, the purpose of the present invention is to provide a method for determining the content of prohibited substances in electronic cigarette liquid to solve the deficiencies in the prior art. The present invention is based on LC-MS / MS technology and can simultaneously determine the content of taurine, caffeine, cannabidiol (CBD), tetrahydrocannabinol (THC), vitamin E and vitamin E acetate in electronic cigarette liquid, thereby meeting the needs of industry supervision, product quality control and safety assessment.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] A method for determining the content of prohibited substances in electronic cigarette liquid, specifically comprising the following steps:

[0009] (1) Sample pretreatment

[0010] First, accurately weigh the e-cigarette liquid sample, then add a solvent to dissolve or dilute it, and finally filter or centrifuge it to obtain an e-cigarette liquid sample solution for LC-MS / MS analysis;

[0011] (2) LC-MS / MS analysis conditions

[0012] Chromatographic conditions: select the chromatographic column, set the mobile phase composition, flow rate, column temperature and gradient elution program;

[0013] Mass spectrometry conditions: electrospray ionization source was used, and ionization voltage, collision energy and scanning range were set;

[0014] (3) Standard curve and quantification

[0015] First, prepare the standard working solution of each target compound, determine the response value of the standard working solution under the set LC-MS / MS analysis conditions, and draw a standard curve; then compare the response value of the e-cigarette liquid sample solution with the standard curve to calculate the content of each target compound in the sample.

[0016] Furthermore, in the above step (1), the solvent is methanol or ethanol.

[0017] Furthermore, in the above step (2), the chromatographic column is a HSS T3 reverse phase chromatographic column.

[0018] Furthermore, in the above step (2), the mobile phase composition is: mobile phase A: 0.1% formic acid solution, mobile phase B: methanol.

[0019] Furthermore, in the above step (2), the flow rate is 0.5 mL / min.

[0020] Furthermore, in the above step (2), the column temperature is 40°C.

[0021] Furthermore, in the above step (2), the gradient elution program is: 0 min, A 80%, B 20%; 1.0 min, A 80%, B 20%; 4.0 min, A 0%, B 100%; 13.0 min, A 0%, B 100%; 13.1 min, A 80%, B 20%; 15.0 min, A 80%, B 20%.

[0022] Furthermore, in the above step (2), the ionization voltage includes capillary voltage and cone voltage.

[0023] Furthermore, the capillary voltage is 2.0 kV in positive mode and 2.0 kV in negative mode; the cone voltage is 20 eV.

[0024] Furthermore, in the above step (3), the target compound includes taurine, caffeine, cannabidiol, tetrahydrocannabinol, vitamin E and vitamin E acetate.

[0025] It can be seen from the above technical solution that compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] 1. Accuracy: The present invention has extremely high sensitivity and selectivity and can accurately detect trace components in electronic cigarette liquid.

[0027] 2. High efficiency: By optimizing the chromatographic and mass spectrometric conditions, the present invention can simultaneously detect multiple components in the e-cigarette liquid, significantly improving the analysis efficiency.

[0028] 3. Wide applicability: The present invention is not only applicable to e-cigarette liquid, but can also be extended to the determination of multiple components in other similar complex matrices.

[0029] 4. Environmental protection: The sample pretreatment process of the present invention is simple, the amount of solvent used is small, and environmental pollution is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The upper picture shows taurine at 1.30 min in negative mode; Figure 1 The figure below shows the positive mode: 4.13min caffeine, 6.34min cannabidiol, 6.92min THC, 10.91min vitamin E, 13.03min vitamin E acetate. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] Example 1

[0033] The method for determining the content of prohibited substances in electronic cigarette liquid specifically comprises the following steps:

[0034] (1) Sample pretreatment

[0035] First, accurately weigh the e-cigarette liquid sample, then add ethanol to dilute it, and finally centrifuge it to obtain the e-cigarette liquid sample solution for LC-MS / MS analysis;

[0036] (2) LC-MS / MS analysis conditions

[0037] Chromatographic conditions: HSS T3 reverse phase column was selected, the mobile phase composition was: mobile phase A: 0.1% formic acid solution, mobile phase B: methanol, the flow rate was 0.5 mL / min, the column temperature was 40 °C, and the gradient elution program was: 0 min, A 80%, B 20%; 1.0 min, A 80%, B 20%; 4.0 min, A 0%, B 100%; 13.0 min, A 0%, B 100%; 13.1 min, A 80%, B20%; 15.0 min, A 80%, B 20%;

[0038] Mass spectrometry conditions: an electrospray ionization source was used, with the capillary voltage set to 2.0 kV in positive mode, 2.0 kV in negative mode, cone voltage set to 20 eV, as well as collision energy and scan range;

[0039] (3) Standard curve and quantification

[0040] First, standard working solutions of taurine, caffeine, cannabidiol, tetrahydrocannabinol, vitamin E and vitamin E acetate were prepared, the response values ​​of the standard working solutions were determined under the set LC-MS / MS analysis conditions, and the standard curve was drawn; then the response value of the e-cigarette liquid sample solution was compared with the standard curve, and the content of each target compound in the sample was calculated.

[0041] Example 2

[0042] The method for determining the content of prohibited substances in electronic cigarette liquid specifically comprises the following steps:

[0043] (1) Sample pretreatment

[0044] First, accurately weigh the e-cigarette liquid sample, then add methanol to dilute it, and finally filter it to obtain the e-cigarette liquid sample solution for LC-MS / MS analysis;

[0045] (2) LC-MS / MS analysis conditions

[0046] Chromatographic conditions: HSS T3 reverse phase column was selected, the mobile phase composition was: mobile phase A: 0.1% formic acid solution, mobile phase B: methanol, the flow rate was 0.5 mL / min, the column temperature was 40 °C, and the gradient elution program was: 0 min, A 80%, B 20%; 1.0 min, A 80%, B 20%; 4.0 min, A 0%, B 100%; 13.0 min, A 0%, B 100%; 13.1 min, A 80%, B20%; 15.0 min, A 80%, B 20%;

[0047] Mass spectrometry conditions: an electrospray ionization source was used, with the capillary voltage set to 2.0 kV in positive mode, 2.0 kV in negative mode, cone voltage set to 20 eV, as well as collision energy and scan range;

[0048] (3) Standard curve and quantification

[0049] First, standard working solutions of taurine, caffeine, cannabidiol, tetrahydrocannabinol, vitamin E and vitamin E acetate were prepared, the response values ​​of the standard working solutions were determined under the set LC-MS / MS analysis conditions, and the standard curve was drawn; then the response value of the e-cigarette liquid sample solution was compared with the standard curve, and the content of each target compound in the sample was calculated.

[0050] Performance Testing

[0051] 1. Validation report of the method for determining the content of 6 banned substances in e-cigarette liquid (LC-MS / MS method).

[0052] 1. Purpose

[0053] Through methodological investigation, the feasibility, accuracy and reliability of the method for determining the content of six banned substances (taurine, caffeine, cannabidiol (CBD), tetrahydrocannabinol (THC), vitamin E and vitamin E acetate) in e-cigarette liquid were verified, providing an executable procedure for daily testing.

[0054] 2. Scope of application

[0055] Applicable to the verification of the determination method of 6 banned substances in e-cigarette liquid.

[0056] 3. Inspection method basis

[0057] The detection program is developed in-house.

[0058] 4. Verification Project

[0059] 4.1 Specificity, linearity and range, limit of quantification (LOQ), limit of detection (LOD), accuracy, precision, and solution stability.

[0060] 4.2 Verification conclusion

[0061] Table 1 Verification conclusion

[0062]

[0063]

[0064] 5. Main reagents and instruments

[0065] 5.1 Ultrapure water (self-made by the company)

[0066] 5.2 Methanol (HPLC) (Honeywell, batch number: V9WG1H) 5.3 Formic acid (Macklin, batch number: C13217137)

[0067] 5.4 Liquid chromatography-mass spectrometry (triple quadrupole) (Instrument number: Eq-C-039)

[0068] 5.5 Analytical balance (1 / 10,000) (Instrument No.: Eq-C-009)

[0069] 5.6 Micropipette (10-100 μL) (Instrument No.: Eq-C-043)

[0070] 5.7 Micropipette (20-200 μL) (Instrument No.: Eq-C-028)

[0071] 5.8 Micropipette (100~1000μL) (Instrument No.: Eq-C-042)

[0072] 6. Standard substances and solutions

[0073] 6.1 Taurine (Tanmo quality inspection, batch number: 22100258, 100 mg / bottle, purity 99.9%)

[0074] 6.2 Caffeine (ANPEL, batch number: CADD-S-280918-AD-1mL, 1000mg / L)

[0075] 6.3 CBD (Weiye measurement, BWB51134-20mg)

[0076] 6.4THC (FinStand, batch number: S128525, 2.00ug / mL)

[0077] 6.5 Vitamin E (China Food and Drug Inspection Institute, 200 mg / bottle)

[0078] 6.6 Vitamin E acetate (batch number: 21040797, 500 mg / bottle, purity 97.3%)

[0079] 7. Detection Methods

[0080] 7.1 Solution preparation (the amount of solution can be adjusted according to actual needs)

[0081] 7.1.1 Sample diluent: ethanol.

[0082] 7.1.2 Mobile phase A: 0.1% formic acid solution

[0083] 7.1.3 Mobile phase B: methanol

[0084] 7.1.4 Preparation of standard curve stock solution: Weigh appropriate amount of prohibited substance standard into 10mL volumetric flask, add ethanol to make up to the mark. The concentration of taurine, caffeine, CBD and vitamin E is 10μg / mL; the concentration of THC and vitamin E acetate is 1μg / mL.

[0085] 7.1.5 Preparation of standard curve solution

[0086] Table 2 Preparation of standard curve solution

[0087]

[0088]

[0089] 7.1.6 Sample solution: weigh 1.0 g of the e-cigarette liquid to be tested into a 10 mL volumetric flask, add ethanol to dilute to the mark, and shake well.

[0090] 7.2 Chromatographic conditions

[0091] Table 3 Chromatographic conditions

[0092]

[0093] Table 4 Mass spectrometry parameters

[0094]

[0095] Table 5 MRM parameters

[0096]

[0097]

[0098] 7.3 Sampling analysis: ethanol solution, standard curve solution, sample solution, etc.

[0099] 7.4 Acceptable criteria for system suitability: Linear correlation coefficient R of each component 2 ≥0.99.

[0100] 8. Verification Procedure

[0101] 8.1 Exclusivity

[0102] 8.1.1 Solution preparation

[0103] Single standard solution of each component at 1 μg / mL;

[0104] Mixed standard solution (linear solution-5);

[0105] Electronic cigarette liquid sample solution: weigh 1.0g of electronic cigarette liquid into a 10mL volumetric flask and add ethanol solution to dilute to the scale;

[0106] E-cigarette liquid spiked sample solution: weigh 1.0 g of e-cigarette liquid into a 10 mL volumetric flask, add 1.0 mL of the mixed standard stock solution, and add ethanol solution to dilute to the scale.

[0107] 8.1.2 Sampling analysis: blank solution and the above test solution.

[0108] 8.1.3 Acceptable criteria: The blank solution has no interference with the test components; the e-cigarette liquid matrix has no interference with the test components.

[0109] 8.1.4 Test results

[0110] Table 6 Retention time

[0111] name Single label retention time min Mixed standard retention time min Taurine 1.30 1.30 caffeine 4.15 4.13 CBD 6.34 6.34 THC 6.92 6.92 Vitamin E 10.90 10.87 Vitamin E Acetate 13.02 13.03

[0112] Table 7 Peak area and recovery

[0113]

[0114]

[0115] Conclusion: The blank ethanol solution has no interference with the detection components; the recovery rates of each banned substance in the e-liquid spiked solution are in the range of 95.0%-109.0%, and the blank e-liquid matrix has no interference with the detection components, indicating that the method has good specificity.

[0116] 8.2 Linearity and Range

[0117] 8.2.1 Solution preparation

[0118] For standard curve solution, refer to "7.1.5".

[0119] 8.2.2 Operation method

[0120] The linear solutions were injected in sequence, and the standard curve was drawn with the peak area ratio of each component in the linear solution as the ordinate and the concentration of each component in the standard working solution as the abscissa.

[0121] 8.2.3 Acceptable standard: Linear correlation coefficient R of the standard curve of each component 2 ≥0.99.

[0122] 8.2.4 Test results

[0123] Table 8 Linear equation and correlation coefficient R 2

[0124] Component name Linear equations <![CDATA[Coefficient of correlation R 2 > Taurine Y=97482.4*x-62.9824 0.999892 is rounded to 0.9998 caffeine Y=4714610*x-6798.71 0.999873 is rounded to 0.9998 CBD Y=588810*x-91.188 0.999950 is rounded to 0.9999 THC Y=1262970*x-69.529 0.999656 is rounded to 0.9996 Vitamin E Y=486988*x+542.609 0.998483 is rounded to 0.9984 Vitamin E Acetate Y=6608500*x+25225.6 0.997817 is rounded to 0.9978

[0125] Conclusion: The minimum linear correlation coefficient of the six banned substances was 0.9978, all of which met the acceptance standard ≥ 0.99, indicating that the method had a good linear relationship.

[0126] Range: Based on the linearity, accuracy, and precision data, when the sample dilution factor is 10, the quantitative range of the taurine, caffeine, cannabidiol (CBD), vitamin E, and vitamin E acetate methods is 0.1μg / mL-10μg / mL, and the quantitative range of the tetrahydrocannabinol (THC) method is 0.01μg / mL-1μg / mL.

[0127] 8.3 Limit of Quantitation and Limit of Detection

[0128] 8.3.1 Solution preparation

[0129] Quantitation limit test solution: The lowest point of linearity is taken as the quantitation limit test solution.

[0130] Detection limit test solution: Add an appropriate amount of ethanol solution to dilute. The dilution concentration can be adjusted according to the actual test results until a suitable concentration is found.

[0131] 8.3.2 Acceptance criteria

[0132] The S / N of each component in the quantification limit solution is ≥10:1.

[0133] The detection limit of each component in the solution is S / N ≥ 3:1.

[0134] 8.3.3 Test results

[0135] Table 9 Quantitation Limit Test Solution

[0136] Components S / N Limit of quantification μg / mL Taurine 194 0.01 caffeine 336 0.01 CBD 84 0.01 THC 19 0.001 Vitamin E 40 0.01 Vitamin E Acetate 641 0.01

[0137] Table 10 Detection limit test solution

[0138] Components S / N Detection limit μg / mL Taurine 51 0.003 caffeine 95 0.003 CBD 20 0.003 THC 5 0.0003 Vitamin E 16 0.003 Vitamin E Acetate 250 0.003

[0139] Conclusion: The minimum S / N of the six banned substances in the quantification limit solution was 19, which met the requirement of ≥10:1, that is, the quantification limit of taurine, caffeine, cannabidiol (CBD), vitamin E and vitamin E acetate was 0.1μg / mL, and the quantification limit of tetrahydrocannabinol (THC) was 0.01μg / mL.

[0140] The minimum S / N of the six banned substances in the detection limit solution was 5, meeting the requirement of ≥3:1, i.e., the detection limit of taurine, caffeine, cannabidiol (CBD), vitamin E and vitamin E acetate was 0.03 μg / mL, and the detection limit of tetrahydrocannabinol (THC) ester was 0.003 μg / mL.

[0141] 8.4 Accuracy

[0142] 8.4.1 Solution preparation

[0143] 8.4.1.1 Sample solution

[0144] Weigh about 1.0g of e-cigarette liquid into a 10mL volume, dilute with ethanol to the scale line, shake well, and you have it.

[0145] 8.4.1.2 Accuracy solution

[0146] Table 11 Accuracy Solution

[0147]

[0148] 8.4.2 Operation method

[0149] The accuracy solutions were injected in sequence, the peak areas were recorded, and the concentrations of the various components in the solution were calculated based on the standard curve.

[0150] 8.4.3 Calculation formula

[0151] Spiked recovery rate = (spike sample measured value - unspike sample measured value) / spike theoretical value × 100%.

[0152] 8.4.4 Acceptability criteria

[0153] The recovery rate of each accuracy solution should be in the range of 80% to 120%.

[0154] 8.4.5 Test results

[0155] Table 12 Theoretical values, measured values ​​and recovery rates

[0156]

[0157] Conclusion: The recoveries of spiked solutions at various concentrations ranged from 82.0% to 114.8%, all meeting the acceptable standard of 80% to 120%.

[0158] 8.5 Precision

[0159] 8.5.1 Repeatability

[0160] Solution preparation: Prepare 6 portions of precision solution according to the accuracy solution-4 in "8.4.1.2".

[0161] Operation method: Inject the solutions separately in sequence, record the peak area, and calculate the concentration of each component in the solution based on the standard curve.

[0162] 8.5.2 Acceptability criteria

[0163] The concentration of each component in 6 precision solutions RSD ≤ 10.0%

[0164] 8.5.3 Intermediate precision

[0165] Different personnel repeat the operations under “8.5.1”.

[0166] 8.5.4 Acceptability criteria

[0167] The RSD of the concentration of each component in the 12 precision solutions was ≤10.0%.

[0168] 8.5.5 Test results

[0169] Table 13 Repeatability test results

[0170] name Taurine caffeine CBD THC Vitamin E Vitamin E Acetate sample-1 0.0993 0.0966 0.0948 0.0091 0.1078 0.1110 sample-2 0.1011 0.0895 0.0888 0.0087 0.1121 0.1030 sample-3 0.1031 0.0896 0.0854 0.0087 0.0954 0.1039 sample-4 0.1080 0.0868 0.0849 0.0087 0.1022 0.1022 sample-5 0.1062 0.0873 0.0852 0.0086 0.1112 0.1032 sample-6 0.1023 0.0834 0.0806 0.0083 0.0964 0.0999 RSD% 3.2 5.0 5.6 3.0 7.1 3.7

[0171] Table 14 Intermediate precision test results

[0172]

[0173]

[0174] Conclusion: The maximum RSD of each component in the 6 repeatability test solutions was 7.1%, which met the acceptance standard of ≤10.0%. The maximum RSD of each component in the 12 test solutions was 8.6%, which met the acceptance standard of ≤10.0%, indicating that the method has good precision.

[0175] 8.6 Solution stability

[0176] 8.6.1 Use repeatability Sample 1 as the solution stability test sample, store it at 10℃ for 1, 3, and 5 days, and repeat the test to confirm the stability of the solution. The mean of the repeatability test results is used as the result of time 0. The storage time can be adjusted according to the actual situation.

[0177] 8.6.2 Acceptability criteria

[0178] The ratio of the post-placement test result to the 0-time result should be in the range of 90%-110%.

[0179] 8.6.3 Test results

[0180] Table 15 1-day solution stability test results

[0181] name Taurine caffeine CBD THC Vitamin E Vitamin E Acetate sample-1 0.0993 0.0966 0.0948 0.0091 0.1078 0.1110 1day 0.0946 0.0987 0.0969 0.0100 0.1010 0.1102 Recovery rate % 95.3 102.2 102.2 109.9 93.7 99.3

[0182] Conclusion: After the test solution was placed at 10°C for 1 day, the ratio of the concentration of the 6 banned substances in the solution to the zero time ranged from 93.7% to 109.9%, all within the range of 90% to 110%, meeting the acceptable standard. This indicates that the test solution is stable at 10°C for 1 day.

[0183] 9. Overall evaluation

[0184] From the above tests, it can be seen that the validation items such as specificity, linearity and range, quantitative limit, detection limit, accuracy, precision, solution stability, etc. of the method all meet the acceptable standards. The linear correlation coefficients of taurine, caffeine, cannabidiol (CBD), tetrahydrocannabinol (THC), vitamin E and vitamin E acetate are 0.9998, 0.9998, 0.9999, 0.9996, 0.9984, and 0.9978, respectively, indicating that the method has a good linear relationship. The recovery rate of the spiked solution of each concentration is 82.0%-114.8%, which meets the acceptable standard of 80%-120%. The maximum RSD of the precision test is 8.6%, which is less than 10.0%, indicating that the method has good precision. The sample solution is stable at 10°C for 1 day, indicating that this method can be used for the determination of the content of 6 banned substances in e-cigarette liquid.

[0185] In summary, it has been verified that the specificity, accuracy and precision of this method meet the requirements of daily use.

[0186] 2. Determination of commercially available products

[0187] 19 batches of commercially available electronic cigarette samples were randomly selected, and the contents of taurine, caffeine, cannabidiol, tetrahydrocannabinol, vitamin E and vitamin E acetate in the electronic cigarette liquids were determined according to the method of Example 1.

[0188] The results are shown in Table 16.

[0189] Table 16 Determination results of the contents of 6 banned substances in 19 batches of commercially available electronic cigarette samples

[0190]

[0191]

[0192] It can be seen from Table 6 that among the 19 batches of commercially available e-cigarette samples, except for the Mini CUP (Raw Coconut Latte) which contained 5.2μg / g of caffeine, no taurine, caffeine, cannabidiol, tetrahydrocannabinol, vitamin E and vitamin E acetate were detected in the other 18 batches of commercially available e-cigarette samples, and all were qualified products.

[0193] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for determining the content of prohibited substances in electronic cigarette liquid, characterized in that: The specific steps include: (1) Sample pretreatment First, accurately weigh the e-cigarette liquid sample, then add a solvent to dissolve or dilute it, and finally filter or centrifuge it to obtain an e-cigarette liquid sample solution for LC-MS / MS analysis; (2) LC-MS / MS analysis conditions Chromatographic conditions: select the chromatographic column, set the mobile phase composition, flow rate, column temperature and gradient elution program; Mass spectrometry conditions: electrospray ionization source was used, and ionization voltage, collision energy and scanning range were set; (3) Standard curve and quantification First, prepare the standard working solution of each target compound, measure the response value of the standard working solution under the set LC-MS / MS analysis conditions, and draw a standard curve; The response value of the e-cigarette liquid sample solution was then compared with the standard curve to calculate the content of each target compound in the sample.

2. The method for determining the content of prohibited substances in electronic cigarette liquid according to claim 1, characterized in that: In step (1), the solvent is methanol or ethanol.

3. The method for determining the content of prohibited substances in electronic cigarette liquid according to claim 1, characterized in that: In step (2), the chromatographic column is a HSS T3 reverse phase chromatographic column.

4. The method for determining the content of prohibited substances in electronic cigarette liquid according to claim 1, characterized in that: In step (2), the mobile phase composition is: mobile phase A: 0.1% formic acid solution, mobile phase B: methanol.

5. The method for determining the content of prohibited substances in electronic cigarette liquid according to claim 1, characterized in that: In step (2), the flow rate is 0.5 mL / min.

6. The method for determining the content of prohibited substances in electronic cigarette liquid according to claim 1, characterized in that: In step (2), the column temperature is 40°C.

7. The method for determining the content of prohibited substances in electronic cigarette liquid according to claim 1, characterized in that: In step (2), the gradient elution program is: 0 min, A 80%, B 20%; 1.0min, A 80%, B 20%; 4.0min, A0%, B 100%; 13.0min, A 0%, B 100%; 13.1min, A 80%, B 20%; 15.0min, A 80%, B 20%.

8. The method for determining the content of prohibited substances in electronic cigarette liquid according to claim 1, characterized in that: In step (2), the ionization voltage includes capillary voltage and cone voltage.

9. The method for determining the content of prohibited substances in electronic cigarette liquid according to claim 8, characterized in that: The capillary voltage is 2.0 kV in positive mode and 2.0 kV in negative mode; the cone voltage is 20 eV.

10. The method for determining the content of prohibited substances in electronic cigarette liquid according to claim 1, characterized in that: In step (3), the target compound includes taurine, caffeine, cannabidiol, tetrahydrocannabinol, vitamin E and vitamin E acetate.

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