A method for detecting chiral isomers of fenmei sandalwood

Abstract

The invention belongs to the technical field of compound analysis, and discloses a method for detecting the chiral isomers of fenmei sandalwood, including: pre-treating the sample to be tested to obtain a neutral sample; using gas chromatography-mass spectrometry for detection, wherein: using a strong polar capillary column for gas chromatography detection; in gas chromatography detection, using split mode injection, the injection port temperature is set to 245-255°C; the column oven temperature program is set to: 120-140°C for 3.5-4.5min; then heating to 225-235°C at a rate of 8-12°C / min, maintaining 8-12min; in mass spectrometry detection, the ion source temperature is 195-205°C; the method is used to achieve baseline separation of chiral isomers of fenmei sandalwood, so as to ensure the effective identification and analysis of chiral isomers of fenmei sandalwood. The method not only ensures the effective identification and analysis of chiral isomers, but also improves the sensitivity and accuracy of detection, and provides a stable and repeatable detection means for the analysis of chiral compounds in complex samples.

Description

Technical Field

[0001] The invention belongs to the field of compound analysis, and particularly relates to a method for detecting chiral isomers of fenmei sandalwood. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] Sandalwood is a rare plant. Sandalwood spice is a very precious fragrance raw material. It has a rich and elegant fragrance with a slightly cool taste. It has good permeability and a long fragrance period. It can be widely used in daily fragrances such as soaps, cosmetics and perfumes.

[0004] At present, the supply of natural sandalwood oil is in short supply, which has led to the increasingly active development of synthetic sandalwood. In recent decades, synthetic sandalwood has become one of the most important synthetic fragrances. Synthetic sandalwood has strong chemical stability and low volatility. It is also a good fixative and can improve the durability and stability of fragrances.

[0005] The chemical name of Fenmei Sandalwood is 2,6-dimethoxy-4-(2,4,6-trimethylphenyl)benzyl alcohol, also known as 2-methyl-4-(2,2,3-trimethyl-3-cyclopenten-1-yl)-4-penten-1-ol, with a molecular formula of C 14 H 24 O, its boiling point is predicted to be 295.3±9.0℃, and its density is 0.900±0.06 g / cm 3 , is an important sandalwood compound with a unique sandalwood aroma. The aroma of Fenmei Sandalwood is described as a very strong and natural sandalwood note. It is widely used in perfumes, cosmetics and daily fragrances to provide a strong sandalwood scent and to increase the fragrance duration of the fragrance, bringing a very natural sandalwood aroma.

[0006] The aroma of fenmei sandalwood mainly comes from its unique chemical structure, especially the presence of cyclopentene ring and double bonds. The specific arrangement of methyl groups and double bonds on the cyclopentene ring, as well as the stereochemistry of the entire molecule, work together to produce the unique aroma of fenmei sandalwood. In particular, in the molecular structure of fenmei sandalwood, the presence of three methyl groups (-CH3) and one double bond (C=C) on the cyclopentene ring provides the molecule with a specific spatial arrangement and electron distribution, which, in interaction with human olfactory receptors, is key to producing aroma perception. In addition, the hydroxyl (-OH) and methyl (-CH3) groups in the molecule also contribute to the aroma properties, which can affect the volatility of the molecule and its interaction with other molecules.

[0007] Fenmei sandalwood isomers have four different stereostructures, and different isomers have different aroma characteristics. Two chiral isomers have different sandalwood smells. (-)-(1'R, 2R) has an elegant and rich sandalwood smell, (-)-(1'S, 2S) has a slightly sweet milky smell of white sandalwood, and the other two chiral isomers have a lighter sandalwood smell. Therefore, the difference in the isomers and proportions in the spices will affect the quality and fragrance of the product.

[0008] In the chemical synthesis process of sandalwood, the probability of synthesizing isomers is equal, so chirality control is required. The type and even ratio of sandalwood isomers in the synthetic product are often detected to optimize the synthesis process, improve the quality or ensure the consistency of the fragrance. Therefore, the detection of chiral molecules is crucial in the application of sandalwood.

[0009] However, in the prior art, there are few studies on the detection and analysis of fenmei sandalwood, especially the detection of fenmei sandalwood and its chiral molecules. The detection method using the prior art produces a single chromatographic peak, which cannot realize the detection of fenmei sandalwood and its chiral molecules. Therefore, a method for detecting the chiral isomers of fenmei sandalwood is urgently needed. Summary of the invention

[0010] In order to solve the deficiencies of the prior art, the object of the present invention is to provide a gas chromatography-mass spectrometry (GC-MS) detection method for fenmei sandalwood and its chiral molecules. The detection method provided by the present invention at least solves the problem that fenmei sandalwood and its chiral molecules have a single chromatographic peak.

[0011] In order to achieve the above object, the technical solution of the present invention is:

[0012] A method for detecting chiral isomers of fenmei sandalwood, comprising:

[0013] Pre-treating the sample to be tested to obtain a neutral sample;

[0014] Gas chromatography-mass spectrometry was used for detection, including:

[0015] Gas chromatography detection using a highly polar capillary column;

[0016] In the gas chromatography detection, the split mode injection was adopted, and the injection port temperature was set to 245-255°C;

[0017] The column oven temperature program was set as follows: 120-140°C for 3.5-4.5 min; then the temperature was raised to 225-235°C at a rate of 8-12°C / min and maintained for 8-12 min;

[0018] In mass spectrometry detection, the ion source temperature is 195-205°C;

[0019] The method is used to achieve baseline separation of the chiral isomers of fenmei sandalwood, so as to ensure effective identification and analysis of the chiral isomers of fenmei sandalwood.

[0020] In the process of developing the detection method, the chromatographic conditions have an important influence on the detection of the substance. Different compounds, including target components or impurities, respond differently to chromatographic conditions such as mobile phase and chromatographic column due to their respective structural characteristics, resulting in peak shape, separation, detection sensitivity or accuracy may not be able to achieve the best effect at the same time. Due to the similarity of the structure of the isomers of fenmei sandalwood, the existing detection method has a single chromatographic peak, which cannot detect fenmei sandalwood and its chiral molecules. The present invention adopts a strong polar capillary column and utilizes the certain sensitivity of the two target molecules to temperature. By changing the initial temperature and the heating program, the separation of fenmei sandalwood and its chiral molecules is improved, so that the two can achieve baseline separation, thereby detecting fenmei sandalwood and its chiral molecules. At the same time, the heating program in the gas chromatography is accurately set according to the molecular structure to avoid decomposition, failure or other adverse reactions at high temperatures.

[0021] In some embodiments, sample pretreatment includes: filtering the sample to be tested with an organic filter membrane to obtain a clear solution; then extracting with a weak alkaline salt solution, neutralizing and removing the inorganic acid, and separating to obtain an organic layer; finally, extracting the organic layer with saturated salt water to remove soluble inorganic salts, separating the liquids, and obtaining a neutral sample, wherein the pH of the neutral sample is 6.5-7.5.

[0022] In some embodiments, the weak base salt solution is a saturated sodium bicarbonate aqueous solution, and the pH of the neutral sample is 7.

[0023] In some embodiments, a neutral sample is taken, diluted with acetonitrile, and a diluted sample is obtained, which is then added to an injection port of a gas chromatograph.

[0024] In some embodiments, during gas chromatography detection, the injection port temperature is set to 250°C;

[0025] The column oven temperature program was set as follows: maintain at 130°C for 4 min; then increase the temperature to 230°C at a rate of 10°C / min and maintain for 10 min.

[0026] In some embodiments, the gas chromatography detection adopts split mode injection with a split ratio of (47-55):1, preferably 50:1.

[0027] In some embodiments, in gas chromatography detection, the column flow rate in the column oven is 2 mL / min, and the carrier gas is helium.

[0028] In some embodiments, the highly polar capillary column is DB-WAXms, with a column length of 30 m, an inner diameter of 0.25 mm, and a film thickness of 0.25 μm.

[0029] In some embodiments, in mass spectrometry detection, the interface temperature between the mass spectrometer and the chromatograph is 242-260° C., and the mass-to-nuclear ratio scanning range is 30-1000.

[0030] In some embodiments, in mass spectrometry detection, the interface temperature between the mass spectrometer and the chromatograph is 250°C, and in mass spectrometry detection, the ion source temperature is 200°C.

[0031] The beneficial effects of the present invention are:

[0032] 1. The present invention provides a method for detecting chiral isomers of fenmei sandalwood. The core technical scheme of the method includes: by using a strong polar capillary column, accurately controlling the injection port temperature and optimizing the heating program, combined with the optimization of sample pretreatment and mass spectrometry detection parameters, the effective separation and identification of chiral isomers are successfully achieved; the present invention achieves the technical effect of efficiently separating chiral isomers of fenmei sandalwood, realizes baseline separation, and makes the chromatographic peaks of each isomer completely separated, and the spectrum peaks are sharp and symmetrical. This method not only ensures the effective identification and analysis of chiral isomers, but also improves the sensitivity and accuracy of detection, and provides a stable and repeatable detection method for the analysis of chiral compounds in complex samples.

[0033] 2. The present invention uses a highly polar capillary column in gas chromatography detection, and by accurately setting the injection port temperature between 245-255°C, and adopting a specific heating program (the initial temperature is set to 120-140°C, maintained for 3.5-4.5 minutes, and then heated to 230°C at a rate of 8-12°C / min, maintained for 8-12 minutes), ensures the gradual separation of chiral isomers in the chromatographic column. These technical means effectively overcome the technical difficulties of achieving baseline separation of chiral isomers of fenmei sandalwood in traditional detection methods, as well as the problems of overheating decomposition or insufficient evaporation of samples that may occur during the injection process. At the same time, by optimizing sample pretreatment (including extraction with saturated sodium bicarbonate aqueous solution to neutralize inorganic acid) and mass spectrometry detection parameters (such as ion source temperature set to 195-205°C, mass-to-nuclear ratio scanning range of 30-1000), interference factors in the sample are further eliminated, and the influence of inorganic acid and soluble inorganic salts on detection is avoided.

[0034] 3. The method provided by the present invention can not only detect the chiral isomer molecules of fenmei sandalwood, but also detect the ratio of different chiral isomers, which provides a basis for optimizing the chemical synthesis process of fenmei sandalwood and obtaining spices with specific fragrances, thereby improving the quality of spices and ensuring the consistency of spices. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0036] Figure 1 This is a GC-MS detection chromatogram of the fenmei sandalwood sample to be tested in Example 1 of the present invention;

[0037] Figure 2 This is a fragment ion mass spectrum of the GC-MS detection of the fenmei sandalwood sample to be tested in Example 1 of the present invention when RT=9.404min;

[0038] Figure 3 This is a fragment ion mass spectrum of the GC-MS detection of the fenmei sandalwood sample to be tested in Example 1 of the present invention when RT=9.568min;

[0039] Figure 4 This is a GC-MS detection chromatogram of the tested sample of Fenmei Sandalwood in Comparative Example 1 of the present invention;

[0040] Figure 5 This is the GC-MS detection chromatogram of the tested sample of Fenmei Sandalwood in Comparative Example 2 of the present invention;

[0041] Figure 6 This is the GC-MS detection chromatogram of the tested sample of Fenmei Sandalwood in Comparative Example 3 of the present invention. DETAILED DESCRIPTION

[0042] In order to solve the shortcomings of the prior art, the purpose of the present invention is to provide a method for detecting chiral isomers of fenmei sandalwood. The spectrum of the method has sharp peaks and good symmetry, and the separation degree of fenmei sandalwood and its chiral molecules is good, which can be used as a qualitative detection method for fenmei sandalwood and its chiral molecules.

[0043] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with specific embodiments. Those skilled in the art should understand that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0044] In the following examples, the gas chromatograph-mass spectrometer is a SHIMADZU GCMS- QP2010 SE gas chromatograph-mass spectrometer; the sample Fenmei sandalwood to be tested is purchased from the market.

[0045] Example 1

[0046] This embodiment provides a method for detecting chiral isomers of fenmei sandalwood, and the detection method comprises the following steps:

[0047] 1. Sample pretreatment

[0048] ① Take Fenmei Sandalwood as the sample to be tested, filter the sample to be tested with an organic filter membrane, remove insoluble matter, and obtain a clear solution; ② Extract with saturated sodium bicarbonate aqueous solution, neutralize and remove inorganic acid, and separate to obtain an organic layer; ③ Re-extract the organic layer with saturated saline, remove soluble inorganic salts, separate the liquids, and obtain a neutral sample with pH = 7. Take 0.1g of the sample and dilute it to 1ml with acetonitrile to obtain the sample solution to be tested.

[0049] 2. Determination of samples to be tested

[0050] Adjust the conditions and parameter settings of the gas chromatography-mass spectrometry (GC-MS), specifically:

[0051] Gas chromatography column: strong polar capillary column DB-WAXms, column length 30m, inner diameter 0.25mm, film thickness 0.25μm;

[0052] Gas phase parameters: injection port temperature: 250°C, split mode injection, split ratio 50:1; column oven temperature program: 130°C, hold for 4 min; then increase the temperature to 230°C at a rate of 10°C / min, hold for 10 min; column flow rate: 2 mL / min; carrier gas: helium.

[0053] Mass spectrometry parameters: ion source temperature: 200°C; GC and MS interface temperature: 250°C; mass-to-nuclear ratio scanning range: 30-1000.

[0054] The sample solution to be tested is injected into the injection port of the gas chromatograph in the gas chromatography-mass spectrometry instrument for detection, and the chromatographic information and mass spectrum information are recorded.

[0055] Example 2

[0056] This embodiment provides a method for detecting chiral isomers of fenmei sandalwood, and the detection method comprises the following steps:

[0057] 1. Sample pretreatment

[0058] ① Take Fenmei Sandalwood as the sample to be tested, filter the sample to be tested with an organic filter membrane, remove insoluble matter, and obtain a clear solution; ② Extract with saturated sodium bicarbonate aqueous solution, neutralize and remove inorganic acid, and separate to obtain an organic layer; ③ Extract the organic layer with saturated salt water, remove soluble inorganic salts, separate the liquids, and obtain a neutral sample with pH=6.5. Take 0.1g of the sample and dilute it to 1ml with acetonitrile to obtain the sample solution to be tested.

[0059] 2. Determination of samples to be tested

[0060] Adjust instrument conditions and parameter settings, specifically:

[0061] Gas chromatography column: strong polar capillary column DB-WAXms, column length 30m, inner diameter 0.25mm, film thickness 0.25μm;

[0062] Gas phase parameters: injection port temperature: 245°C, split mode injection, split ratio 47:1; column oven temperature program: 120°C, hold for 4.5 min; then increase the temperature to 225°C at a rate of 12°C / min, hold for 12 min; column flow rate: 2 mL / min; carrier gas: helium.

[0063] Mass spectrometry parameters: ion source temperature: 195°C; GC and MS interface temperature: 242°C; mass-to-nuclear ratio scanning range: 30-1000.

[0064] The sample solution to be tested is injected into the injection port of the gas chromatograph in the gas chromatography-mass spectrometry instrument for detection, and the chromatographic information and mass spectrum information are recorded.

[0065] Example 3

[0066] This embodiment provides a method for detecting chiral isomers of fenmei sandalwood, and the detection method comprises the following steps:

[0067] 1. Sample pretreatment

[0068] ① Take Fenmei Sandalwood as the sample to be tested, filter the sample to be tested with an organic filter membrane, remove insoluble matter, and obtain a clear solution; ② Extract with saturated sodium bicarbonate aqueous solution, neutralize and remove inorganic acid, and separate to obtain an organic layer; ③ Re-extract the organic layer with saturated salt water, remove soluble inorganic salts, separate the liquids, and obtain a neutral sample with pH=7.5. Take 0.1g of the sample and dilute it to 1ml with acetonitrile to obtain the sample solution to be tested.

[0069] 2. Determination of samples to be tested

[0070] Adjust instrument conditions and parameter settings, specifically:

[0071] Gas chromatography column: strong polar capillary column DB-WAXms, column length 30m, inner diameter 0.25mm, film thickness 0.25μm;

[0072] Gas phase parameters: injection port temperature: 255°C, split mode injection, split ratio 55:1; column oven temperature program: 140°C, hold for 3.5 min; then increase the temperature to 235°C at a rate of 8°C / min, hold for 8 min; column flow rate: 2 mL / min; carrier gas: helium.

[0073] Mass spectrometry parameters: ion source temperature: 205°C; GC and MS interface temperature: 260°C; mass-to-nuclear ratio scanning range: 30-1000.

[0074] The sample solution to be tested is injected into the injection port of the gas chromatograph in the gas chromatography-mass spectrometry instrument for detection, and the chromatographic information and mass spectrum information are recorded.

[0075] Comparative Example 1

[0076] This comparative example provides a method for detecting chiral isomers of fenmei sandalwood, which is different from Example 1 in that:

[0077] The gas chromatography column was a nonpolar capillary column DB-1ms, with a length of 30 m, an inner diameter of 0.53 mm, and a film thickness of 1.0 μm;

[0078] Gas phase parameters: injection port temperature: 280°C, split mode injection, split ratio 50:1; column oven temperature program: 100°C, hold for 3 min; then heat to 250°C at a rate of 8°C / min, hold for 10 min; column flow rate: 3 mL / min; carrier gas: helium.

[0079] Mass spectrometry parameters: ion source temperature: 200°C; GC and MS interface temperature: 290°C; mass-to-nuclear ratio scanning range: 30-1000.

[0080] Comparative Example 2

[0081] This comparative example provides a method for detecting chiral isomers of fenmei sandalwood, which is different from Example 1 in that:

[0082] The gas chromatography column is a weak polar capillary column DB-5ms, with a column length of 50 m, an inner diameter of 0.32 mm, and a film thickness of 1.05 μm;

[0083] Gas phase parameters: Inlet temperature: 280°C, split mode injection, split ratio 50:1; Column oven temperature program: 170°C, hold for 3 min; then increase the temperature to 220°C at a rate of 3°C / min, and then increase the temperature to 280°C at a rate of 20°C / min and hold for 5 min; Column flow rate: 2 mL / min; Carrier gas: helium.

[0084] Mass spectrometry parameters: ion source temperature: 200°C; GC and MS interface temperature: 290°C; mass-to-nuclear ratio scanning range: 30-1000.

[0085] Comparative Example 3

[0086] This comparative example provides a method for detecting chiral isomers of fenmei sandalwood, which is different from Example 1 in that:

[0087] The gas chromatography column is a weak polar capillary column DB-5ms, with a column length of 30 m, an inner diameter of 0.25 mm, and a film thickness of 0.25 μm;

[0088] Gas phase parameters: injection port temperature: 280°C, split mode injection, split ratio 50:1; column oven temperature program: 75°C, hold for 3.5 min; then increase the temperature to 120°C at a rate of 6°C / min, and then increase the temperature to 280°C at a rate of 20°C / min, hold for 5 min; column flow rate: 2 mL / min; carrier gas: helium.

[0089] Mass spectrometry parameters: ion source temperature: 200°C; GC and MS interface temperature: 280°C; mass-to-nuclear ratio scanning range: 30-1000.

[0090] Results Analysis

[0091] In the chromatograms obtained by testing the samples of Examples 1-3, the tested fenmei sandalwood showed double peaks with good separation, and the two could achieve baseline separation. Taking Example 1 as an example, Figure 1 The chromatogram of the sample of the fenmei sandalwood to be tested in Example 1 of the present invention shows a double peak in the chromatogram of Example 1. The separation degree of the fenmei sandalwood and its chiral molecules reaches 1.2, which is a good separation degree. The fenmei sandalwood and its chiral molecules can achieve baseline separation. Figure 2 , Figure 3 It can be seen that the compounds to be tested in Example 1 are fenmei sandalwood and its chiral molecules, that is, two chiral isomeric molecules of fenmei sandalwood. Figure 1 The chromatographic peak at the middle molecular retention time T=9.404min corresponds to (-)-(1'R,2R)-2-methyl-4-(2,2,3-trimethyl-3-cyclopenten-1-yl)-4-penten-1-ol, and the chromatographic peak at T=9.568min corresponds to (-)-(1'S,2S)-2-methyl-4-(2,2,3-trimethyl-3-cyclopenten-1-yl)-4-penten-1-ol. The area ratio of the two is 52:46. The mass ratio of the two molecules (-)-(1'R,2R) and (-)-(1'S,2S) is 52:46, and the difference between the two ratios is not much.

[0092] Figure 4 This is the chromatogram of the sample of Fenmei Sandalwood to be tested in Comparative Example 1 of the present invention, Figure 4 It can be seen that the sample to be tested has a single chromatographic peak, and its chiral molecular chromatographic peak does not appear.

[0093] Figure 5 This is the chromatogram of the sample of Fenmei Sandalwood to be tested in Comparative Example 2 of the present invention, Figure 5 It can be seen that the sample to be tested has a single chromatographic peak, and its chiral molecular chromatographic peak does not appear.

[0094] Figure 6 This is the chromatogram of the sample of Fenmei Sandalwood to be tested in Comparative Example 3 of the present invention, Figure 6It can be seen that the sample to be tested has a split peak and its chiral molecular chromatographic peak appears, but the separation is poor and the two cannot achieve baseline separation.

[0095] In summary, the present invention adopts a strong polar capillary column, and utilizes the certain sensitivity of fenmei sandalwood and its chiral molecules to temperature. By changing the initial temperature and the heating program, the separation degree of fenmei sandalwood and its chiral molecules is improved, so that the two can reach baseline separation, thereby detecting fenmei sandalwood and its chiral molecules. The method has fast analysis speed and sharp peak shape of the spectrum, good symmetry, and the separation degree of fenmei sandalwood and its chiral molecules is good, which can be used as a qualitative detection method for fenmei sandalwood and its chiral molecules. At the same time, the heating program in the gas chromatography is accurately set according to the molecular structure, and the influence of decomposition, failure or other adverse reactions at high temperature can also be avoided. This method not only ensures the effective identification and analysis of chiral isomers, but also improves the sensitivity and accuracy of detection, and provides a stable and repeatable detection method for the analysis of chiral compounds in complex samples. At the same time, according to the area of ​​the chromatographic peak, the approximate ratio of the two chiral isomers of fenmei sandalwood can be obtained.

[0096] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for detecting chiral isomers of fenmei sandalwood, characterized in that: The method comprises: Pre-treating the sample to be tested to obtain a neutral sample; Gas chromatography-mass spectrometry was used for detection, including: Gas chromatography detection using a highly polar capillary column; In the gas chromatography detection, the split mode injection was adopted, and the injection port temperature was set to 245-255°C; The column oven temperature program was set as follows: 120-140°C for 3.5-4.5 min; then the temperature was raised to 225-235°C at a rate of 8-12°C / min and maintained for 8-12 min; In mass spectrometry detection, the ion source temperature is 195-205°C; The method is used to achieve baseline separation of the chiral isomers of fenmei sandalwood to ensure effective identification and analysis of the chiral isomers of fenmei sandalwood; The sample pretreatment includes: filtering the sample to be tested with an organic filter membrane to obtain a clear solution, then extracting with a weak alkaline salt solution, neutralizing to remove the inorganic acid, and separating to obtain an organic layer; finally, extracting the organic layer with saturated salt water to remove the soluble inorganic salts, separating the liquids, and obtaining a neutral sample, the pH of the neutral sample is 6.5-7.5; Gas chromatography detection was performed using split mode injection with a split ratio of (47-55):1; In mass spectrometry detection, the interface temperature between the mass spectrometer and the chromatograph is 242-260°C, and the mass-to-nuclear ratio scanning range is 30-1000.

2. The method according to claim 1, characterized in that The weak alkaline salt solution is a saturated sodium bicarbonate aqueous solution, and the pH of the neutral sample is 7.

3. The method according to claim 1, characterized in that Take a neutral sample, dilute it with acetonitrile, obtain a diluted sample, and add it to the injection port of the gas chromatography detection.

4. The method according to claim 1, characterized in that: In the gas chromatography test, the injection port temperature was set to 250 °C; The column oven temperature program was set as follows: maintain at 130°C for 4 min; then increase the temperature to 230°C at a rate of 10°C / min and maintain for 10 min.

5. The method according to claim 1, characterized in that In the gas chromatography detection, the column flow rate in the column oven was 2 mL / min, and the carrier gas was helium.

6. The method according to claim 1, characterized in that The highly polar capillary column is DB-WAXms, with a column length of 30 m, an inner diameter of 0.25 mm, and a film thickness of 0.25 μm.

7. The method according to claim 1, characterized in that In mass spectrometry detection, the interface temperature between the mass spectrometer and the chromatograph is 250°C, and in mass spectrometry detection, the ion source temperature is 200°C.

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