Method for detecting content of methanol in liquid essence

Abstract

The invention provides a method for detecting the content of methanol in liquid essence, and belongs to the field of pharmaceutical analysis. According to the method, a capillary column method is adopted, dimethyl polysiloxane is taken as a stationary phase, headspace sampling is carried out, and the content of methanol is calculated by peak area according to an external standard method. Compared with the prior art, the method has the advantages of high specificity, good reproducibility, high sensitivity and the like.

Description

Technical Field

[0001] This invention relates to a method for detecting methanol content in liquid flavorings in the field of pharmaceutical analysis. Background Technology

[0002] Liquid flavorings are excipients used in many oral solution products in the pharmaceutical industry, such as L-carnitine oral solution and acetaminophen / pseudoephedrine / chlorpheniramine oral solution. Due to manufacturing processes, methanol residue may remain in liquid flavorings. Methanol accumulates in the body, primarily damaging the optic nerve; therefore, even small amounts can cause chronic poisoning, with symptoms including headache, nausea, blurred vision, and blindness. The Chinese Pharmacopoeia (2025 edition) regulates methanol residue levels. Currently, the standard for detecting methanol content in liquid flavorings is GB / T 7917.4-1987, using gas chromatography with a packed column (glass or stainless steel column, 2m × φ4mm, filled with GDX-102 (60-80 mesh) support). The Chinese Pharmacopoeia (2025 Edition, Volume IV) requires a resolution of 1.5 or higher between each chromatographic peak. However, this method suffers from low column efficiency, resulting in a resolution of 1.5 or higher between the methanol peak and other peaks. Furthermore, the outdated standard GB / T 7917.4-1987 has not been updated, and packed columns are rarely used nowadays. Therefore, developing a method for detecting methanol content in liquid fragrances that is highly specific, reproducible, sensitive, simple to operate, widely applicable in terms of detection equipment and instruments, and low in cost is a pressing new challenge. Summary of the Invention

[0003] The main objective of this invention is to provide a method for detecting methanol content in liquid flavorings. This method uses gas chromatography with dimethyl polysiloxane as the stationary phase. This method has the advantages of high specificity, good reproducibility, high sensitivity, simple operation, wide application of detection equipment and instruments, and low detection cost.

[0004] The objective of this invention is achieved as follows: a method for detecting methanol content in liquid flavorings, the method employing a capillary column method, comprising the following steps:

[0005] (1) Chromatographic conditions

[0006] Column: Dimethylpolysiloxane as the stationary phase;

[0007] Column temperature: Initial column temperature 30-60℃, maintain for 3-9 minutes; then increase to 170-190℃ at a rate of 15-25℃ per minute, maintain for 2-5 minutes;

[0008] Inlet temperature: 190~240℃;

[0009] Detector: Hydrogen flame ionization detector, detector temperature 280–350℃;

[0010] (2) Preparation of control solution

[0011] (3) Preparation of the test solution

[0012] (4) Measurement method

[0013] Inject the test solution and the control solution into the headspace separately, record the chromatograms, and the resolution of the methanol peak with the adjacent solvent peak should be greater than 1.5. Calculate the resolution by peak area according to the external standard method.

[0014] The chromatographic conditions also include:

[0015] Carrier gas: nitrogen, flow rate of 3-5 ml / min;

[0016] Flow split ratio 20:1 to 50:1;

[0017] The headspace bottle equilibrium temperature is 80–90℃, the equilibrium time is 15–25 minutes, and the transfer line temperature is 85–115℃.

[0018] The chromatographic column uses 100% dimethylpolysiloxane as the stationary phase; the chromatographic column is selected from one of DM-1, DB-1, SPB-1, HP-1, BP-1, and 007-1, and the specifications of the chromatographic column are selected from "45~160m×0.5~0.6mm×4.5~5.5μm", preferably, the specifications of the chromatographic column are selected from "45~65m×0.5~0.6mm×4.5~5.5μm".

[0019] The specifications of the chromatographic column are selected from "50m×0.53mm×5μm" or "60m×0.53mm×5μm".

[0020] The preparation method of the control solution is as follows: accurately measure 2-3 ml of methanol into a 100 ml volumetric flask, dilute with water to the mark, shake well, then accurately measure 3-5 ml of the above solution into a 50 ml volumetric flask, dilute with 50-70% ethanol solution to the mark, shake well, accurately measure 2-5 ml into a 10 ml headspace vial, and seal.

[0021] The test solution is prepared by accurately measuring 2-4 ml of the product and placing it in a 10 ml headspace vial, sealing it, and using it as the test solution.

[0022] The preparation method of the control solution is as follows: accurately measure 2.5 ml of methanol into a 100 ml volumetric flask, dilute with water to the mark, shake well, then accurately measure 4 ml of the above solution into a 50 ml volumetric flask, dilute with 60% ethanol solution to the mark, shake well, accurately measure 3 ml into a 10 ml headspace vial, and seal; the preparation method of the test solution is as follows: accurately measure 3 ml of this product into a 10 ml headspace vial, seal, and use as the test solution; this product is selected from liquid flavorings, and the liquid flavorings are selected from one of orange-flavored liquid flavorings, lemon-flavored liquid flavorings, and banana-flavored liquid flavorings.

[0023] The detection method includes the following steps:

[0024] (1) Chromatographic conditions

[0025] Chromatographic column: using 100% dimethylpolysiloxane as the stationary phase; the specifications of the chromatographic column are selected from "49~61m×0.50~0.55mm×4.5~5.5μm";

[0026] Column temperature: Initial column temperature 35-45℃, maintain for 5-7 minutes; then increase to 175-185℃ at a rate of 17-22℃ per minute, maintain for 2-4 minutes;

[0027] Inlet temperature: 190~220℃;

[0028] Detector: Hydrogen flame ionization detector, detector temperature is 280~330℃;

[0029] Carrier gas: nitrogen, flow rate of 3.5–4.5 ml / min;

[0030] Flow split ratio 25:1 to 35:1;

[0031] The headspace bottle equilibrium temperature is 80–90℃, the equilibrium time is 15–25 minutes, and the transfer line temperature is 90–110℃.

[0032] (2) Control solution: Accurately measure 2-3 ml of methanol into a 100 ml volumetric flask, dilute with water to the mark, shake well, then accurately measure 3-5 ml of the above solution into a 50 ml volumetric flask, dilute with 50-70% ethanol solution to the mark, shake well, accurately measure 2-4 ml into a 10 ml headspace vial, and seal.

[0033] (3) Test solution: Accurately measure 2-4 ml of this product into a 10 ml headspace vial, seal it, and use it as the test solution;

[0034] (4) Measurement method

[0035] Inject the test solution and the control solution into the headspace separately, record the chromatograms, and the resolution of the methanol peak with the adjacent solvent peak should be greater than 1.5. Calculate the resolution by peak area according to the external standard method.

[0036] The detection method includes the following steps:

[0037] (1) Chromatographic conditions

[0038] Chromatographic column: DM-1, 50m × 0.53mm × 5μm;

[0039] Column temperature: Initial column temperature 40℃, maintain for 6 minutes; then increase to 180℃ at a rate of 20℃ per minute, maintain for 3 minutes;

[0040] Inlet temperature: 200℃;

[0041] Detector: Hydrogen flame ionization detector, detector temperature is 300℃;

[0042] Carrier gas: nitrogen, flow rate 4 ml / min;

[0043] Flow split ratio 30:1;

[0044] The headspace vial equilibrium temperature was 85℃, the equilibrium time was 20 minutes, and the transfer line temperature was 100℃.

[0045] (2) Control solution: Accurately measure 2.5 ml of methanol into a 100 ml volumetric flask, dilute with water to the mark, shake well, then accurately measure 4 ml of the above solution into a 50 ml volumetric flask, dilute with 60% ethanol solution to the mark, shake well, accurately measure 3 ml into a 10 ml headspace vial, and seal.

[0046] (3) Test solution: Accurately measure 3 ml of this product into a 10 ml headspace vial, seal it, and use it as the test solution;

[0047] (4) Measurement method

[0048] Inject the test solution and the control solution into the headspace separately, record the chromatograms, and the resolution of the methanol peak with the adjacent solvent peak should be greater than 1.5. Calculate the resolution by peak area according to the external standard method.

[0049] The limit of quantification for methanol is 2.3 μg / ml, and the limit of detection for methanol is 0.7 μg / ml.

[0050] The formula for calculating methanol content based on peak area using the external standard method is as follows:

[0051]

[0052] In the formula:

[0053] A 供 : Peak area of ​​methanol in the test solution;

[0054] P: Purity of the control, %;

[0055] A 对 : Peak area of ​​methanol in the control solution.

[0056] The key point of this invention is to provide a method for detecting methanol content in liquid fragrances. Its pharmaceutical principle is as follows: through the overall synergistic effect of various technical features within the technical solution of this application, especially the synergy of the chromatographic column, column temperature, injection port temperature, detector temperature, and injection method, the technical effect of detecting methanol content in liquid fragrances is achieved. The resolution between methanol and its adjacent solvent chromatographic peaks is greater than 1.5, and the limit of quantification for methanol is as low as 2.3 μg / ml.

[0057] Compared with existing technologies, a new method for detecting methanol content in liquid flavorings has the advantages of high specificity, good reproducibility, and high sensitivity, and will be widely used in the field of methanol content analysis in liquid flavorings. Attached Figure Description

[0058] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0059] Figure 1 This is the chromatogram of the methanol control solution [0.15% (V / V)] of the original method.

[0060] Figure 2 This is the chromatogram of the methanol control solution [0.20% (V / V)] of Example 1 of the present invention.

[0061] Figure 3 This is a chromatogram of the liquid fragrance test solution from Embodiment 1 of the present invention. Detailed Implementation

[0062] The following examples will help to understand the present invention, but these examples are only for illustration and the present invention is not limited thereto.

[0063] Example 1

[0064] 1. Chromatographic conditions

[0065] Gas chromatograph (Agilent 8890), capillary column method, column with 100% dimethylpolysiloxane as stationary phase (DM-1, 50m × 0.53mm × 5μm, DIKMA); initial column temperature 40℃, maintained for 6 minutes; then increased to 180℃ at a rate of 20℃ / min, maintained for 3 minutes; injection port temperature 200℃; detector was flame ionization detector (FID), detector temperature 300℃; carrier gas was nitrogen, flow rate 4ml / min; split ratio 30:1; headspace vial equilibration temperature 85℃, equilibration time 20 minutes, transfer line temperature 100℃.

[0066] 2. Control solution: Accurately measure 2.5 ml of methanol into a 100 ml volumetric flask, dilute with water to the mark, and shake well. Then accurately measure 4 ml of the above solution into a 50 ml volumetric flask, dilute with 60% ethanol solution to the mark, and shake well. Accurately measure 3 ml into a 10 ml headspace vial and seal.

[0067] 3. Test solution: Accurately measure 3 ml of this product (orange flavor liquid flavoring) and place it in a 10 ml headspace vial. Seal the vial to obtain the test solution.

[0068] 4. Measurement Method

[0069] Inject the test solution and the control solution separately into the headspace and record the chromatograms. See Appendix. Figure 3 and attached Figure 2 The resolution between methanol and its adjacent solvent peaks should be greater than 1.5. Calculated by peak area using the external standard method, the resolution should not exceed 0.2%.

[0070] 5. Calculation formula

[0071]

[0072] In the formula:

[0073] A 供 : Peak area of ​​methanol in the test solution;

[0074] P: Purity of the control, %;

[0075] A 对 : Peak area of ​​methanol in the control solution;

[0076] 6. Calculation Results

[0077] The peak areas of the control solution for 5 consecutive injections are:

[0078] A1=1289.70A2=1163.28A3=1179.18A4=1141.72A5=1165.88

[0079] A 对 Average = 1187.95, RSD = 5.0%

[0080] The peak area of ​​sample 1 is: A 供1 =35.86

[0081] The peak areas of the test sample are: A 供2 =33.54

[0082]

[0083] Note: Sources of raw materials and reagents used in this application

[0084] name Source (supplier) batch number Orange-flavored liquid flavoring Jiangxi Aipu Biotechnology Co., Ltd. 20240918 Ethanol (99.9%) McLean C16314805 Methanol (99.9%) Fisher F22M9S202

[0085] Example 2

[0086] This study systematically examined the specificity, linearity, limit of quantitation and limit of detection, repeatability, accuracy and robustness of this method.

[0087] 1. Exclusivity

[0088] 1.1. Standard: Blank solvent and degradation impurities should not interfere with the determination of methanol;

[0089] 1.2. Measurement methods and results

[0090] Blank solvent: Take 3 ml of 60% ethanol-water blank solvent and place it in a 10 ml headspace vial. Seal the vial and inject it into the gas chromatograph. Record the chromatogram. The results show that the blank solvent and degradation impurities do not interfere with the determination of methanol.

[0091] 2. Limit of Quantification and Limit of Detection

[0092] 2.1 Standard: Limit of quantitation S / N≈10; Limit of detection S / N≈3.

[0093] 2.2. Measurement methods and results

[0094] Accurately measure 2.5 ml of methanol into a 100 ml volumetric flask, dissolve and dilute to the mark with water, and shake well to prepare the reference stock solution. Dilute an appropriate amount of the reference stock solution with 60% ethanol and water to prepare a series of dilute solutions of different concentrations. Take 3 ml of each dilute solution and place it in a headspace vial, seal, and inject via headspace. Record the chromatogram. The concentration corresponding to S / N≈10 is the limit of quantitation, and the injection is repeated once; the concentration corresponding to S / N≈3 is the limit of detection.

[0095] Validate Project methanol Limit of Quantification 2.3 μg / ml Detection limit 0.7μg / ml

[0096] 3. Linear

[0097] 3.1 Standard: Correlation coefficient (r) > 0.99; Intercept ratio: not greater than 100%; Impurity concentration peak area 15%.

[0098] 3.2 Measurement methods and results

[0099] Accurately measure 2.5 ml of methanol into a 100 ml volumetric flask, dissolve and dilute with water to the mark, and shake well to prepare the reference stock solution. Prepare linear solutions of different concentrations according to the table below.

[0100] serial number Take a volume of the stock solution. Final volume after dilution linear points 1 — — LOQ 2 1ml 50ml 25％ 3 2ml 50ml 50％ 4 3ml 50ml 75％ 5 4ml 50ml 100％ 6 5ml 50ml 125％

[0101] Accurately measure the linear solutions 1 through 6 above, injecting each concentration once. Plot a regression curve using peak area against the corresponding sample concentration, and calculate the regression equation and the corresponding linear regression coefficient. The correlation coefficient r should be > 0.99.

[0102]

[0103]

[0104] 3.3 Conclusion: The methanol concentration and peak area showed a good linear relationship in the concentration range of 2.3 μg / ml to 1978.0 μg / ml, and the correlation coefficient (r) was 0.9994, which met the limit requirement of r > 0.99. The intercept ratio was 0.3%, which met the standard requirements, indicating that the linear determination results of this method were good.

[0105] 4. Accuracy

[0106] 4.1 Standard: Recovery rate: 90%–108%, RSD ≤ 10%.

[0107] 4.2 Measurement methods and results:

[0108] Select 10 portions of a batch of samples. Accurately measure 3 ml of one portion into a headspace vial, seal it, and use it as the background solution. Place appropriate amounts of the remaining 9 portions into 10 ml volumetric flasks, and add 0.6 ml, 0.8 ml, and 1.0 ml of the reference stock solution (accurately measure 2.5 ml of methanol into a 100 ml volumetric flask, dissolve and dilute to the mark with water, and shake well) to each flask. Dilute the test sample to the mark, shake well, and accurately measure 3 ml of each portion into a headspace vial. Seal and shake well to use as the recovery test solution. The average recovery rate should be between 90% and 108%, and the relative standard deviation of the 9 recovery rate data should not exceed 10%.

[0109]

[0110] 4.3 Conclusion: The average recovery rate was 98%, and the RSD was 3.9%, which met the limit requirements, indicating that the method has good accuracy.

[0111] 5. Analyze repeatability

[0112] 5.1 Standard: Result < 0.2%, RSD ≤ 10%.

[0113] 5.2 Measurement methods and results:

[0114] Accurately measure 6 portions of this product, 3 ml each, and place them in 10 ml headspace vials. Seal the vials and use them as repeatable sample solutions. The RSD of the 6 methanol results should be ≤10%.

[0115] methanol 1 2 3 4 5 6 average value% RSD% content% 0.0010 0.00091 0.00095 0.00097 0.00099 0.00094 0.00096 3.5

[0116] 5.3 The results show that the RSD value of the detection data is 3.5%, which meets the limit requirements, indicating that the analysis of this method has good repeatability.

[0117] 6. Intermediate precision

[0118] 6.1 Standard: Result < 0.2%, RSD ≤ 15%.

[0119] 6.2 Measurement methods and results

[0120] Take this product and perform the methanol determination method. Have another laboratory technician perform the determination six times at different times using different instruments. Compare the results of the two technicians. The RSD of the result obtained by each technician should be ≤10%; the RSD of the result obtained by all technicians should be ≤15%.

[0121] methanol 1 2 3 4 5 6 average value% RSD% content% 0.00099 0.0010 0.0010 0.0010 0.00098 0.00098 0.0010 1.3

[0122] The RSD for all 12 test samples was 3.8%.

[0123] 6.3 Conclusion: The RSD values ​​of the detection data were 3.5% and 1.3%, and the RSD of the results of all 12 test samples was 3.8%, which met the limit requirements, indicating that the intermediate precision of this method was good.

[0124] 7. Durability

[0125] 7.1 Standard: When there are minor changes in flow rate, initial temperature, injection port temperature, and different batches of chromatographic columns, the methanol determination results should not change significantly. The RSD of methanol content under each corresponding condition and under normal conditions should not exceed 10%, and the system suitability should meet the requirements.

[0126] 7.2 Measurement methods and results

[0127] Under the proposed gas chromatography conditions, the initial column temperature (40±2℃), flow rate (4.0±0.5ml / min), and injection port temperature (210℃) were appropriately varied. The methanol determination of different batches of columns was performed according to the method under the methanol determination section.

[0128]

[0129]

[0130] 7.3. Conclusion: The RSD value of the detection data under all conditions was 6.3%, and the system suitability met the requirements. This indicates that when there are slight changes in flow rate, initial temperature, injection port temperature, and different batches of chromatographic columns, the methanol determination results do not change significantly, and the system has good robustness.

[0131] The above data from the methanol testing methodology validation test show that all validation parameters meet the regulatory requirements for validation tests. This method is accurate, simple, stable, durable, scientific, and reliable, and can effectively control the methanol content in liquid flavorings.

[0132] Example 3

[0133] Experimental exploration of methods for determining methanol content in liquid flavorings:

[0134]

[0135] Final determination of the testing method:

[0136] The chromatographic column DM-1 (50m×0.53mm×5μm) was used, with headspace injection (split ratio 30:1). The peak shape was normal, the column efficiency was high (N=42000), the control showed good linearity, and the test sample did not interfere.

[0137] Example 4

[0138] Original method for determining methanol content in liquid flavorings

[0139] 1. Solution preparation

[0140] Methanol control solution: Accurately measure 2.5 ml of methanol and place it in a 100 ml volumetric flask pre-filled with 95 ml of water. Then dilute with water to the mark and mix well to obtain the methanol control solution. This solution is a 2.5% methanol solution.

[0141] Methanol control sequence solutions: Accurately measure 1.00, 2.00, 3.00, and 4.00 ml of methanol control solution into 50 ml volumetric flasks, add 30 ml of ethanol to each, and then dilute with water to the mark. Shake well to obtain the methanol control sequence solutions. These control sequences contain 0.05%, 0.10%, 0.15%, and 0.20% methanol, respectively.

[0142] Test solution: Take this product (orange-flavored liquid flavoring) directly as the test solution.

[0143] 2. Chromatographic conditions

[0144] Detector: Flame ionization detector; Column: Stainless steel column, 2m×φ4mm, packed with GDX-102 (60-80 mesh) support; Vaporization temperature: 190℃; Detector temperature: 180℃; Column temperature: 170℃; Nitrogen flow rate: 40ml / min; Hydrogen flow rate: 40ml / min; Air flow rate: 500ml / min; Injection volume: 1μl.

[0145] 3. Determination method

[0146] Precisely measure 1.0 μl of methanol-free ethanol and inject it into the chromatograph; no impurity peaks should appear.

[0147] Precisely measure 1 μl of each methanol reference sequence solution and inject them into the gas chromatograph. Record the chromatograms. (See Appendix) Figure 1 And plot the peak area-methanol concentration (v / v) curve.

[0148] Accurately measure 1 μl of the test solution, inject it into the gas chromatograph, record the chromatogram, and calculate the corresponding methanol concentration from the standard curve based on the peak area.

Claims

1. A method for detecting methanol content in liquid flavorings, characterized in that, The method employs the capillary column method and includes the following steps: (1) Chromatographic conditions Column: Dimethylpolysiloxane as the stationary phase; Column temperature: Initial column temperature 30-60℃, maintain for 3-9 minutes; then increase to 170-190℃ at a rate of 15-25℃ per minute, maintain for 2-5 minutes; Inlet temperature: 190~240℃; Detector: Hydrogen flame ionization detector, detector temperature 280–350℃; (2) Preparation of control solution (3) Preparation of the test solution (4) Measurement method Inject the test solution and the control solution into the headspace separately, record the chromatograms, and the resolution of the methanol peak with the adjacent solvent peak should be greater than 1.

5. Calculate the resolution by peak area according to the external standard method.

2. The method for detecting methanol content in liquid flavorings according to claim 1, characterized in that, The chromatographic conditions also include: Carrier gas: nitrogen, flow rate of 3-5 ml / min; Flow split ratio 20:1 to 50:1; The headspace bottle equilibrium temperature is 80–90℃, the equilibrium time is 15–25 minutes, and the transfer line temperature is 85–115℃.

3. The method for detecting methanol content in liquid flavorings according to claim 1, characterized in that, The chromatographic column uses 100% dimethylpolysiloxane as the stationary phase; the chromatographic column is selected from one of DM-1, DB-1, SPB-1, HP-1, BP-1, and 007-1, and the specifications of the chromatographic column are selected from "45~160m×0.5~0.6mm×4.5~5.5μm", preferably, the specifications of the chromatographic column are selected from "45~65m×0.5~0.6mm×4.5~5.5μm".

4. The method for detecting methanol content in liquid flavorings according to claim 3, characterized in that, The specifications of the chromatographic column are selected from "50m×0.53mm×5μm" and "60m×0.53mm×5μm".

5. The method for detecting methanol content in liquid flavorings according to claim 1, characterized in that, The preparation method of the control solution is as follows: accurately measure 2-3 ml of methanol into a 100 ml volumetric flask, dilute with water to the mark, shake well, then accurately measure 3-5 ml of the above solution into a 50 ml volumetric flask, dilute with 50-70% ethanol solution to the mark, shake well, accurately measure 2-5 ml into a 10 ml headspace vial, and seal. The test solution is prepared by accurately measuring 2-4 ml of the product and placing it in a 10 ml headspace vial, sealing it, and using it as the test solution.

6. The method for detecting methanol content in liquid flavorings according to claim 5, characterized in that: The preparation method of the control solution is as follows: accurately measure 2.5 ml of methanol into a 100 ml volumetric flask, dilute with water to the mark, shake well, then accurately measure 4 ml of the above solution into a 50 ml volumetric flask, dilute with 60% ethanol solution to the mark, shake well, accurately measure 3 ml into a 10 ml headspace vial, and seal; the preparation method of the test solution is as follows: accurately measure 3 ml of this product into a 10 ml headspace vial, seal, and use as the test solution; this product is selected from liquid flavorings, and the liquid flavorings are selected from one of orange-flavored liquid flavorings, lemon-flavored liquid flavorings, and banana-flavored liquid flavorings.

7. The method for detecting methanol content in liquid flavorings according to claim 2, characterized in that, The detection method includes the following steps: (1) Chromatographic conditions Chromatographic column: using 100% dimethylpolysiloxane as the stationary phase; the specifications of the chromatographic column are selected from "49~61m×0.50~0.55mm×4.5~5.5μm"; Column temperature: Initial column temperature 35-45℃, maintain for 5-7 minutes; then increase to 175-185℃ at a rate of 17-22℃ per minute, maintain for 2-4 minutes; Inlet temperature: 190~220℃; Detector: Hydrogen flame ionization detector, detector temperature is 280~330℃; Carrier gas: nitrogen, flow rate of 3.5–4.5 ml / min; Flow split ratio 25:1 to 35:1; The headspace bottle equilibrium temperature is 80–90℃, the equilibrium time is 15–25 minutes, and the transfer line temperature is 90–110℃. (2) Control solution: Accurately measure 2-3 ml of methanol into a 100 ml volumetric flask, dilute with water to the mark, shake well, then accurately measure 3-5 ml of the above solution into a 50 ml volumetric flask, dilute with 50-70% ethanol solution to the mark, shake well, accurately measure 2-4 ml into a 10 ml headspace vial, and seal. (3) Test solution: Accurately measure 2-4 ml of this product into a 10 ml headspace vial, seal it, and use it as the test solution; (4) Measurement method Inject the test solution and the control solution into the headspace separately, record the chromatograms, and the resolution of the methanol peak with the adjacent solvent peak should be greater than 1.

5. Calculate the resolution by peak area according to the external standard method.

8. The method for detecting methanol content in liquid flavorings according to claim 2, characterized in that: The detection method includes the following steps: (1) Chromatographic conditions Chromatographic column: DM-1, 50m × 0.53mm × 5μm; Column temperature: Initial column temperature 40℃, maintain for 6 minutes; then increase to 180℃ at a rate of 20℃ per minute, maintain for 3 minutes; Inlet temperature: 200℃; Detector: Hydrogen flame ionization detector, detector temperature is 300℃; Carrier gas: nitrogen, flow rate 4 ml / min; Flow split ratio 30:1; The headspace vial equilibrium temperature was 85℃, the equilibrium time was 20 minutes, and the transfer line temperature was 100℃. (2) Control solution: Accurately measure 2.5 ml of methanol into a 100 ml volumetric flask, dilute with water to the mark, shake well, then accurately measure 4 ml of the above solution into a 50 ml volumetric flask, dilute with 60% ethanol solution to the mark, shake well, accurately measure 3 ml into a 10 ml headspace vial, and seal. (3) Test solution: Accurately measure 3 ml of this product into a 10 ml headspace vial, seal it, and use it as the test solution; (4) Measurement method Inject the test solution and the control solution into the headspace separately, record the chromatograms, and the resolution of the methanol peak with the adjacent solvent peak should be greater than 1.

5. Calculate the resolution by peak area according to the external standard method.

9. The method for detecting methanol content in liquid flavorings according to claim 1, characterized in that: The limit of quantification for methanol is 2.3 μg / ml, and the limit of detection for methanol is 0.7 μg / ml.

10. The method for detecting methanol content in liquid flavorings according to claim 1, characterized in that: The formula for calculating methanol content based on peak area using the external standard method is as follows: In the formula: A 供 : Peak area of ​​methanol in the test solution; P: Purity of the control, %; A 对 : Peak area of ​​methanol in the control solution.

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