A normal phase liquid chromatography detection method for benzenesulfonyl chloride

Abstract

The invention relates to the field of analytical chemistry, and in particular to a normal phase liquid chromatography detection method for benzenesulfonyl chloride. The method comprises the following chromatographic conditions: a chromatographic column comprises a chromatographic column with bonded cellulose or bonded amylose as a stationary phase; the mobile phase is selected from methyl tert-butyl ether, n-hexane, n-heptane, dichloromethane, tetrahydrofuran, or a combination of two or more thereof; and isocratic elution is performed. The method of the invention avoids the hydrolysis of benzenesulfonyl chloride, greatly improves the solution stability and reproducibility of a substance to be tested, ensures the quantitative accuracy of the substance to be tested in trace detection, can meet the sensitivity detection requirements for genotoxic impurities, and effectively solves the problem of detecting the quality of benzenesulfonyl chloride in auxiliary material benzenesulfonic acid.

Description

Technical Field

[0001] The invention relates to the field of analytical chemistry, and in particular to a normal phase liquid chromatography detection method for benzenesulfonyl chloride. Background Art

[0002] Benzenesulfonyl chloride is a chlorinated derivative of benzenesulfonic acid. It has high reactivity and diverse chemical properties. Therefore, it has important applications in drug synthesis, dye industry, chemical analysis and other fields. In drug synthesis, benzenesulfonyl chloride is often used as an intermediate for the synthesis of various drugs, such as drugs containing benzenesulfonylamino structures, and antibiotics. In the dye industry, benzenesulfonyl chloride is one of the important raw materials for the synthesis of aniline dyes. By reacting with aromatic amines, dyes of various colors can be synthesized. Benzenesulfonyl chloride is also commonly used in chloro substitution reactions and electrophilic substitution reactions in organic synthesis reactions. As an important organic synthesis intermediate and chemical reagent, benzenesulfonyl chloride plays an important role in various fields. With the continuous development and improvement of chemical technology, the detection methods and analytical techniques of benzenesulfonyl chloride are also constantly improving, providing a reliable guarantee for its wider application.

[0003] Cisatracurium besylate is a muscle relaxant that is a must-have drug in anesthesia surgery. It is clinically used in surgery and other operations as well as intensive care treatment. It is used as an adjuvant drug for general anesthesia or as a sedative in the intensive care unit (ICU). It can relax skeletal muscles and make tracheal intubation and mechanical ventilation easier. Currently, non-depolarizing muscle relaxants are mainly used, and the main drugs include cisatracurium, rocuronium, vecuronium, mivacurium, etc. Among them, the most widely used is cisatracurium, which is an isomer of atracurium besylate and is a strong, medium-acting, non-depolarizing muscle relaxant.

[0004] Benzenesulfonic acid, as an excipient in cisatracurium benzenesulfonate injection, acts as a pH regulator and stabilizer. Combined with the synthesis process of benzenesulfonic acid, it is necessary to analyze and conduct risk assessment on the potential mutagenic impurity benzenesulfonyl chloride in the excipient benzenesulfonic acid. According to ICHM7, the medication duration of this product is less than 1 month, the maximum daily intake allowed is 120 μg / day, and the maximum daily dose of this product is 890 mg. Therefore, the safety limit of the impurity benzenesulfonyl chloride is 134.8 ppm.

[0005] Since acyl chlorides are unstable, especially sulfonyl chloride, which is very easy to hydrolyze, is unstable under reversed-phase liquid chromatography conditions, and the accuracy of the determination results is poor, the literature often uses gas phase (GC-FID) detection methods. However, the test sample in this product is benzenesulfonic acid, which is highly acidic. In gas phase detection, it produces various impurity peaks due to thermal decomposition. The test sample is unstable, which seriously interferes with the determination of the impurity content of benzenesulfonyl chloride.

[0006] There are also many reports on the use of aniline or alcohol as derivatization reagents to detect substances derived from acyl chlorides. This method has complex sample pretreatment, poor recovery and reproducibility, and poses a higher challenge to the quantitative accuracy of trace detection of acyl chloride genotoxic impurities.

[0007] Therefore, it is necessary to develop a new detection method for impurity benzenesulfonyl chloride. Summary of the invention

[0008] In view of the above technical status, the present invention aims to provide a normal phase liquid chromatography detection method for benzenesulfonyl chloride, the method of the present invention comprises the chromatographic conditions of:

[0009] The chromatographic column includes a chromatographic column with bonded cellulose or bonded amylose as the stationary phase;

[0010] The mobile phase is selected from methyl tert-butyl ether, n-hexane, n-heptane, dichloromethane, tetrahydrofuran, or a combination of two or more thereof;

[0011] Perform isocratic elution.

[0012] In the present invention, as one of the embodiments, the mobile phase is selected from a combination of methyl tert-butyl ether and n-hexane, n-heptane, dichloromethane or tetrahydrofuran;

[0013] In the present invention, as one of the embodiments, when the mobile phase is selected from a combination of methyl tert-butyl ether and n-hexane, n-heptane, dichloromethane or tetrahydrofuran, the concentration of methyl tert-butyl ether in the mobile phase is 100% to 90%, preferably 100%, and the concentration of n-hexane, n-heptane, dichloromethane or tetrahydrofuran in the mobile phase is 0% to 10%; preferably, the concentration of n-heptane or n-hexane is 0% to 10%.

[0014] As an exemplary illustration, the concentration of methyl tert-butyl ether in the mobile phase can be 100%, 99%, 98%, 97%, 96%, 95%, 94%, 93%, 92%, 91% or 90%.

[0015] As an exemplary illustration, the concentration of n-heptane or n-hexane in the mobile phase can be 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%.

[0016] In the present invention, as one of the embodiments, the mobile phase is methyl tert-butyl ether.

[0017] In the present invention, as one of the embodiments, the solid filler of the chromatographic column in the normal phase liquid chromatography is further selected from bonded dimethyl amylose or bonded cellulose-tris(3,5-dichlorophenylcarbamate).

[0018] In the present invention, as one of the embodiments, the chromatographic column of the normal phase liquid chromatography is Lux i-Amylose-1 or Lux i-Cellulose-5 or Daicel chromatographic column.

[0019] In the present invention, as one of the embodiments, the chromatographic column of the normal phase liquid chromatography method adopts Daicel IC (filler: covalently bonded cellulose-tris(3,5-dichlorophenylcarbamate), 250 mm×4.6 mm, 5 μm) as the chromatographic column.

[0020] In the present invention, as one of the embodiments, the detection wavelength of the normal phase liquid chromatography is 230 to 234 nm, preferably 232 nm.

[0021] In the present invention, as one of the embodiments, the flow rate of the normal phase liquid chromatography is 0.4 ml / min to 1.0 ml / min, preferably 0.6 ml / min.

[0022] In the present invention, as one of the embodiments, the normal phase liquid chromatography injection volume is 5 μl~15μl, preferably 10μl.

[0023] In the present invention, as one of the embodiments, the column temperature of the normal phase liquid chromatography is 25°C to 35°C, preferably 30°C.

[0024] In the present invention, as one of the embodiments, the method further comprises the following steps:

[0025] (1) Preparation of test solution: Take 30 mg of benzenesulfonic acid and place it in a 10 ml volumetric flask, add methyl tert-butyl ether to dilute to the mark, and shake well;

[0026] (2) Preparation of reference stock solution: Take 10 mg of benzenesulfonyl chloride reference substance, weigh it accurately, place it in a 100 ml volumetric flask, dilute it to the mark with methyl tert-butyl ether, shake it well, and prepare a benzenesulfonyl chloride reference solution containing 0.1 mg per 1 ml. Accurately transfer 1 ml of the solution to a 50 ml volumetric flask, dilute it to the mark with methyl tert-butyl ether, shake it well, and prepare a benzenesulfonyl chloride reference stock solution containing 2000 ng per 1 ml;

[0027] (3) Preparation of reference solution: Accurately pipette 2 ml of benzenesulfonyl chloride reference stock solution into a 10 ml volumetric flask, dilute to scale with methyl tert-butyl ether, and shake well to prepare a benzenesulfonyl chloride reference solution containing 400 ng per 1 ml.

[0028] (4) Normal phase liquid chromatography detection, chromatographic conditions are:

[0029] Daicel IC (filler: covalently bonded cellulose-tris(3,5-dichlorophenylcarbamate), 250 mm × 4.6 mm, 5 μm) was used as the chromatographic column;

[0030] Methyl tert-butyl ether was used as the mobile phase;

[0031] The flow rate is 0.6 ml / min;

[0032] The injection volume was 10 μl;

[0033] The column temperature was 30°C;

[0034] The detection wavelength is 232nm;

[0035] Isocratic elution.

[0036] In the detection methods reported in the literature, due to the easy hydrolysis of acyl chloride substances in reversed phase liquid chromatography, it is necessary to perform derivatization pretreatment operations on the samples, the steps are cumbersome, and the derivatization efficiency of different types of acyl chloride substances is different, and the recovery rate cannot be guaranteed; in gas chromatography determination, since the main component benzenesulfonic acid is easily decomposed by heat, it interferes with impurity detection, and acyl chloride substances are highly corrosive to gas chromatograph components such as injection needles and chromatographic columns, which sharply shortens the service life of related equipment hardware. The normal phase liquid chromatography detection method of the present invention can save the complicated derivatization method for sample pretreatment, adopt a solvent and mobile phase inert to the reaction of benzenesulfonyl chloride to directly dilute and inject, and separate and detect by high performance liquid chromatography of the normal phase system, thereby avoiding the hydrolysis of benzenesulfonyl chloride, greatly improving the solution stability and reproducibility of the substance to be tested, ensuring the quantitative accuracy of the substance to be tested in trace detection, meeting the sensitivity detection requirements of genotoxic impurities, and effectively solving the quality detection problem of benzenesulfonyl chloride in auxiliary material benzenesulfonic acid.

[0037] Since the present invention does not require sample pretreatment, a normal phase chromatography system with an inert solvent such as methyl tert-butyl ether can be directly used for dilution and sample injection detection, and thus the invention has the characteristics of simple operation and high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 : Chromatogram of the test solution spiked with 100% limit concentration under normal conditions in Example 1;

[0039] Figure 2 : Chromatogram of reference substance solution under the conditions of Example 2;

[0040] Figure 3 : Chromatogram of reference substance solution under the conditions of Example 3;

[0041] Figure 4 : Chromatogram of reference substance solution under the conditions of Example 4;

[0042] Figure 5 : Chromatogram of reference substance solution under the conditions of Example 5;

[0043] Figure 6 : Chromatogram of reference substance solution under the conditions of Example 6;

[0044] Figure 7 : Chromatogram of reference substance solution under the conditions of Example 7;

[0045] Figure 8 : Chromatogram of reference substance solution under the conditions of Comparative Example 1;

[0046] Fig. 9 : Chromatogram of reference substance solution under the conditions of Comparative Example 2;

[0047] Fig.10 : Chromatogram of blank solution;

[0048] Fig.11 : Chromatogram of benzenesulfonyl chloride reference solution;

[0049] Fig.12 : Chromatogram of test solution. DETAILED DESCRIPTION

[0050] The following examples are used to further illustrate the present invention, but are not intended to limit the effective scope of the present invention in any way.

[0051] Example 1: Normal chromatographic conditions:

[0052] Daicel IC (filler: covalently bonded cellulose-tris(3,5-dichlorophenylcarbamate), 250 mm×4.6 mm, 5 μm) was used as the chromatographic column, methyl tert-butyl ether was used as the mobile phase for isocratic elution, the flow rate was 0.6 ml / min, the injection volume was 10 μl, the column temperature was 30°C, the detection wavelength was 232 nm, and the solvent was methyl tert-butyl ether.

[0053] The test results are as attached Figure 1 As shown, the separation degree between benzenesulfonyl chloride and the nearby chromatographic peaks is 2.7, and the signal-to-noise ratio is about 220, which can meet the requirements for quantitative detection of genotoxic impurities.

[0054] Example 2: Replacement of Daicel IA chromatographic column with different fillers

[0055] Chromatographic conditions: Daicel IA (filler: covalently bonded amylose-tris(3,5-dimethylphenylcarbamate), 250 mm × 4.6 mm, 5 μm) was used as the chromatographic column, methyl tert-butyl ether was used as the mobile phase for isocratic elution, the flow rate was 0.6 ml / min, the injection volume was 10 μl, the column temperature was 30°C, the detection wavelength was 232 nm, and the solvent was methyl tert-butyl ether.

[0056] As attached Figure 2 As shown, the separation degree between benzenesulfonyl chloride and the nearby chromatographic peaks is 4.5, and the signal-to-noise ratio is about 180, which can meet the requirements for quantitative detection of genotoxic impurities.

[0057] Example 3: Changing to different mobile phases

[0058] Chromatographic conditions: Daicel IC (250 mm × 4.6 mm, 5 μm) was used as the chromatographic column, methyl tert-butyl ether-n-hexane (90:10) was used as the mobile phase for isocratic elution, the flow rate was 0.6 ml / min, the injection volume was 10 μl, the column temperature was 30 °C, the detection wavelength was 232 nm, and the solvent was methyl tert-butyl ether.

[0059] As attached Figure 3 As shown, there is no interference near the chromatographic peak of benzenesulfonyl chloride, but the baseline drifts slightly, and the signal-to-noise ratio is about 50, that is, when the impurity benzenesulfonyl chloride contains a 20% limit concentration, the quantitative limit detection requirement can be met.

[0060] Example 4: (Change column temperature to 25°C)

[0061] Chromatographic conditions: Daicel IC (250 mm × 4.6 mm, 5 μm) was used as the chromatographic column, methyl tert-butyl ether was used as the mobile phase for isocratic elution, the flow rate was 0.6 ml / min, the input volume was 10 μl, the column temperature was 25°C, the detection wavelength was 232 nm, and the solvent was methyl tert-butyl ether.

[0062] As attached Figure 4 As shown, the separation degree between benzenesulfonyl chloride and the nearby chromatographic peaks is 3.0, and the signal-to-noise ratio is about 200, which can meet the requirements for quantitative detection of genotoxic impurities.

[0063] Example 5: (Change column temperature to 35°C)

[0064] Chromatographic conditions: Daicel IC (250 mm × 4.6 mm, 5 μm) was used as the chromatographic column, methyl tert-butyl ether was used as the mobile phase for isocratic elution, the flow rate was 0.6 ml / min, the input volume was 10 μl, the column temperature was 35°C, the detection wavelength was 232 nm, and the solvent was methyl tert-butyl ether.

[0065] As attached Figure 5 As shown, the separation degree between benzenesulfonyl chloride and the nearby chromatographic peaks is 2.5, and the signal-to-noise ratio is about 250, which can meet the requirements for quantitative detection of genotoxic impurities.

[0066] Example 6: (Replacing the low flow rate)

[0067] Chromatographic conditions: Daicel IC (250 mm × 4.6 mm, 5 μm) was used as the chromatographic column, methyl tert-butyl ether was used as the mobile phase for isocratic elution, the flow rate was 0.4 ml / min, the input volume was 10 μl, the column temperature was 30°C, the detection wavelength was 232 nm, and the solvent was methyl tert-butyl ether.

[0068] As attached Figure 6 As shown, the signal-to-noise ratio of the chromatographic peak of benzenesulfonyl chloride at a limit concentration of 100% is about 131. The sensitivity decreases as the flow rate decreases, but the signal-to-noise ratio of the quantitative limit can still meet the requirement of not less than 10 at this flow rate.

[0069] Example 7: (Change to high flow rate)

[0070] Chromatographic conditions: Daicel IC (250 mm × 4.6 mm, 5 μm) was used as the chromatographic column, methyl tert-butyl ether was used as the mobile phase for isocratic elution, the flow rate was 1.0 ml / min, the input volume was 10 μl, the column temperature was 30°C, the detection wavelength was 232 nm, and the solvent was methyl tert-butyl ether.

[0071] As attached Figure 7 As shown, the separation degree between the chromatographic peak of benzenesulfonyl chloride at the 100% limit concentration and the nearby chromatographic peaks is 2.3, and the separation degree with the solvent peak becomes worse, but it can still meet the requirement of separation degree not less than 1.5.

[0072] Comparative Example 1: (The solvent type was changed to methanol, and the analyte was more active and unstable)

[0073] Chromatographic conditions: Daicel IC (250 mm × 4.6 mm, 5 μm) was used as the chromatographic column, methyl tert-butyl ether was used as the mobile phase for isocratic elution, the flow rate was 0.6 ml / min, the injection volume was 10 μl, the column temperature was 30°C, the detection wavelength was 232 nm, and the solvent was methanol.

[0074] As attached Figure 8 As shown, when methanol is used as a diluent, benzenesulfonyl chloride reacts with methanol to form methyl benzenesulfonate (the retention time of the methyl benzenesulfonate reference solution is 8.1 minutes), which results in a lower detection amount of benzenesulfonyl chloride impurity.

[0075] Comparative Example 2: Changing the wavelength, low sensitivity (201 nm is the second maximum absorption wavelength of benzenesulfonyl chloride)

[0076] Chromatographic conditions: Daicel IC (250 mm × 4.6 mm, 5 μm) was used as the chromatographic column, methyl tert-butyl ether was used as the mobile phase for isocratic elution, the flow rate was 0.6 ml / min, the input volume was 10 μl, the column temperature was 30°C, the detection wavelength was 201 nm, and the solvent was methyl tert-butyl ether.

[0077] As attached Fig. 9As shown, the baseline noise is larger than 232 nm, and the signal-to-noise ratio of the chromatographic peak of benzenesulfonyl chloride at the 100% limit concentration is about 16, which cannot meet the detection requirements of the genotoxic impurity limit.

[0078] Example 8: Method Verification Experiment

[0079] Verification items include: system suitability, specificity, limit of quantification and limit of detection, linearity and range, accuracy, precision (repeatability, reproducibility), and solution stability. The specific verification standards and results are shown in Table 1:

[0080] Table 1

[0081]

[0082]

[0083] 1) Specificity verification

[0084] The methyl tert-butyl ether reagent was injected into the liquid chromatograph as the blank solution, reference solution and test solution respectively. The experimental results are shown in the attached Figures 10-12 The blank and test samples had no interference with the detection of benzenesulfonyl chloride, and the method had strong specificity.

[0085] 2) Injection precision verification

[0086] Accurately measure 10 μl of 400 ng / ml reference solution, inject it 5 times continuously, record the chromatogram, and calculate the relative standard deviation (RSD) (%) based on the peak area. The results are shown in Table 2.

[0087] Table 2 Benzenesulfonyl chloride injection precision experimental results (n = 5)

[0088]

[0089] The experimental results show that after 5 consecutive injections, the RSD of the peak area of ​​benzenesulfonyl chloride is 0.11%, not more than 2.0%, and the precision of this method is good.

[0090] 3) Quantification limit and detection limit verification

[0091] The benzenesulfonyl chloride reference solution was diluted step by step, and the concentration with a signal-to-noise ratio of not less than 10 was the quantitative limit concentration. The peak area RSD of 6 consecutive injections was calculated to be no more than 15.0%. The test results are shown in Table 3.

[0092] Table 3 Results of quantitative limit and detection limit of benzenesulfonyl chloride

[0093]

[0094] The experimental results show that the detection limit of benzenesulfonyl chloride in this analytical method is 30.24ng / ml, equivalent to 10.1ppm of the test sample concentration; the quantification limit of benzenesulfonyl chloride is 100.6ng / ml, equivalent to 33.5ppm of the test sample concentration; the signal-to-noise ratio of the quantification limit of 6 needles is greater than 10, and the relative standard deviation RSD of the peak area is 2.71%, which is less than 5.0%, indicating that this method has high sensitivity and can meet the needs of detecting genotoxic impurities in benzenesulfonyl chloride.

[0095] 4) Linearity and range verification

[0096] The benzenesulfonyl chloride reference substance stock solution was diluted 20, 10, 5, 3.3, and 2.5 times to prepare linear solutions of different concentrations, that is, the linear study covered the quantitative limit to 200% of the limit concentration. 10 μl of each of the above solutions was injected, and a linear regression was performed on the peak area versus the concentration (ng / ml) to obtain the regression equation. The test results are shown in Table 4.

[0097] Table 4 Benzenesulfonyl chloride linearity and range results

[0098]

[0099] The experimental results show that under the analytical method, the concentration and peak area of ​​benzenesulfonyl chloride have good linearity in the concentration range of 100.6 to 804.78 ng / ml (LOQ to 200%), the absolute value of the y-axis intercept is 0.68% of the 100% limit concentration, which is less than 10% of the 100% limit concentration, and the correlation coefficient r=0.9999.

[0100] 5) Accuracy verification

[0101] The spike recovery method was used for determination. 30 mg of the auxiliary material benzenesulfonic acid test sample was taken, accurately weighed, and placed in a 10 ml volumetric flask. Different volumes of benzenesulfonyl chloride reference substance stock solution were added to prepare 50%, 100%, and 150% three concentration levels of spiked test solution. Three portions of each concentration were prepared in parallel as the accuracy test solution. The recovery rate of benzenesulfonyl chloride was calculated by the peak area according to the reference substance external standard method. The test results are shown in Table 5.

[0102] Table 5 Benzenesulfonyl chloride accuracy results

[0103]

[0104] The experimental results show that when known amounts of benzenesulfonyl chloride with three different impurity limit levels of low, medium and high are added to the sample, the recovery rate of the measured value in the range of 50% to 150% in this analysis method is between 91.74% and 96.13% compared with the theoretical value, and the RSD of the recovery rate of 9 samples is 1.6%, which is less than 5.0%, indicating that this method can accurately quantify the test solution containing a certain amount of benzenesulfonyl chloride impurity and the relative standard deviation of the test results is very small. It can be seen that this method can be applied to actual sample analysis.

[0105] 6) Precision verification

[0106] Two experimenters independently prepared 6 100% spiked test solutions on different dates using different instruments. The recovery of benzenesulfonyl chloride in each spiked test solution was calculated using the peak area according to the reference external standard method. The test results are shown in Table 6.

[0107] Table 6 Benzenesulfonyl chloride precision experimental results

[0108]

[0109] The experimental results showed that the repeatability of benzenesulfonyl chloride test results of 6 100% limit spiked test solutions was RSD of 0.93%. Another experimenter, using different instruments on different dates, prepared 6 100% limit spiked test solutions with RSD of 5.21%. The RSD among the 12 samples was 5.26%, not more than 10%, indicating that the method has good precision. It can be seen that for test samples containing 100% limit impurity benzenesulfonyl chloride, this method has accurate and stable detection capabilities.

[0110] 7) Verification of the stability of the test solution

[0111] The stability of the benzenesulfonyl chloride reference solution and the 100% limit concentration spiked test solution placed at room temperature for 29 hours was investigated respectively. The peak area results measured at different times were compared with the initial results to investigate the stability of the reference solution and the test solution. The test results are shown in Table 7.

[0112] Table 7 Benzenesulfonyl chloride solution stability results

[0113]

[0114] The experimental results show that when liquid chromatography was performed at different time points, the peak areas of benzenesulfonyl chloride impurity measured in the reference solution and the 100% spiked test solution were compared with the peak areas of the initial determination, and the changes were no more than 10%, indicating that the impurity to be measured was stable at room temperature for 29 hours under this determination method. It can be seen that under this method system, the impurity benzenesulfonyl chloride is not easily hydrolyzed and has good stability. The genotoxic impurity benzenesulfonyl chloride in the 100% spiked test sample can be stably and effectively detected.

Claims

1. A normal phase liquid chromatography detection method for benzenesulfonyl chloride, characterized in that, The method comprises the following chromatographic conditions: The chromatographic column includes a chromatographic column with bonded cellulose or bonded amylose as the stationary phase; The mobile phase is selected from methyl tert-butyl ether, n-hexane, n-heptane, dichloromethane, tetrahydrofuran, or a combination of two or more thereof; Perform isocratic elution.

2. The method according to claim 1, characterized in that The mobile phase is selected from a combination of methyl tert-butyl ether and n-hexane, n-heptane, dichloromethane or tetrahydrofuran.

3. The method according to claim 2, characterized in that In the mobile phase, the concentration of methyl tert-butyl ether is 100% to 90%; the concentration of n-hexane, n-heptane, dichloromethane or tetrahydrofuran is 0% to 10%.

4. The method according to claim 1, characterized in that The mobile phase is methyl tert-butyl ether.

5. The method according to claim 1, characterized in that The solid filler of the chromatographic column is selected from bonded dimethyl amylose or bonded cellulose-tris(3,5-dichlorophenylcarbamate).

6. The method according to claim 5, characterized in that The chromatographic column comprises Lux i-Amylose-1, Lux i-Cellulose-5 or Daicel chromatographic column; Preferably, Daicel IC (filler: covalently bonded cellulose-tris(3,5-dichlorophenylcarbamate), 250 mm×4.6 mm, 5 μm) is used as the chromatographic column.

7. The method according to claim 1, characterized in that The normal phase liquid chromatography detection wavelength is 230-234 nm, preferably 232 nm.

8. The method according to claim 1, characterized in that The flow rate of the normal phase liquid chromatography is 0.4 ml / min to 1.0 ml / min, preferably 0.6 ml / min.

9. The method according to claim 1, characterized in that: The injection volume of the normal phase liquid chromatography is 5 μl to 15 μl, preferably 10 μl.

10. The method according to claim 1, characterized in that The column temperature of the normal phase liquid chromatography is 25°C to 35°C, preferably 30°C.

11. The method according to claim 1, characterized in that: The method further comprises the following steps: (1) Preparation of test solution: Take 30 mg of benzenesulfonic acid and place it in a 10 ml volumetric flask, add methyl tert-butyl ether to dilute to the mark, and shake well; (2) Preparation of reference stock solution: accurately weigh 10 mg of benzenesulfonyl chloride reference substance, place in a 100 ml volumetric flask, dilute to scale with methyl tert-butyl ether, shake well, and prepare a benzenesulfonyl chloride reference solution containing 0.1 mg per ml; accurately transfer 1 ml of the solution to a 50 ml volumetric flask, dilute to scale with methyl tert-butyl ether, shake well, and prepare a benzenesulfonyl chloride reference stock solution containing 2000 ng per ml; (3) Preparation of reference solution: Accurately pipette 2 ml of benzenesulfonyl chloride reference stock solution into a 10 ml volumetric flask, dilute to scale with methyl tert-butyl ether, and shake well to prepare a benzenesulfonyl chloride reference solution containing 400 ng per 1 ml. (4) Normal phase liquid chromatography detection, chromatographic conditions are: Daicel IC (filler: covalently bonded cellulose-tris(3,5-dichlorophenylcarbamate), 250 mm × 4.6 mm, 5 μm) was used as the chromatographic column; Methyl tert-butyl ether was used as the mobile phase; The flow rate is 0.6 ml / min; The injection volume was 10 μl; The column temperature was 30°C; The detection wavelength is 232nm; Isocratic elution.

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