Method for detecting related substances in 2-aminothiophenol

Abstract

The invention belongs to the technical field of pharmaceutical analysis, and particularly relates to a method for detecting related substances in 2-aminothiophenol. According to the detection method of the 2-aminothiophenol related substances, provided by the invention, a reversed-phase HPLC (High Performance Liquid Chromatography) determination method is provided, the detection of the 2-aminothiophenol related substances can be realized, the specificity, linearity, precision, sensitivity, precision and durability of the method are good, and the method is suitable for quality control of 2-aminothiophenol.

Description

Technical Field

[0001] The present invention belongs to the technical field of pharmaceutical analysis, and particularly relates to a high performance liquid chromatography method for related substances in 2-aminobenzenethiol. Background Art

[0002] 2-aminobenzenethiol is an important organic synthesis intermediate and has a wide range of uses in multiple fields. It can be used as a key fragment for constructing complex drug molecular structures, and through chemical reactions, it combines with other functional groups to form compounds with specific pharmacological activities. 2-aminobenzenethiol, CAS number: 137-07-5, has the following structural formula:

[0003] 。

[0004] Dotinurad is a drug used to treat gout and hyperuricemia, and 2-aminobenzenethiol is a key intermediate for synthesizing Dotinurad. Diltiazem is a non-dihydropyridine calcium channel blocker, mainly used to treat hypertension, angina pectoris and certain arrhythmias, and 2-aminobenzenethiol is an important intermediate for synthesizing Diltiazem. In addition, 2-aminobenzenethiol can also be used to synthesize other benzothiazole compounds, which have a wide range of biological activities in the medical field and can be used to treat various diseases such as cancer and cardiovascular diseases.

[0005] The synthesis process route of 2-aminobenzenethiol is as follows:

[0006] 。

[0007] 2-aminobenzenethiol is extremely easy to be oxidized and deteriorated in the air, and there are few detection methods for 2-aminobenzenethiol. Zhang Weimin. Determination method of o-aminobenzenethiol. Liaoning Chemical Industry, 1994: 61-62 disclosed the determination method of o-aminobenzenethiol. The determination methods of o-aminobenzenethiol mainly include spectrophotometry, volumetry and chromatography. Among them, spectrophotometry is easy to operate, but the relative error is relatively large. The relative error of volumetry is 0.25%, and chromatography is mainly used to detect trace o-aminobenzenethiol and its homologues.

[0008] The currently retrieved determination methods have the following problems: (1) When using ultraviolet-visible spectrophotometry to determine the content of 2-aminobenzenethiol, the relative error is relatively large, and the oxidized impurities cannot be quantitatively confirmed; (2) When using gas chromatography to determine the purity of 2-aminobenzenethiol, due to the high boiling point of the oxidized impurities and difficulty in gasification, it cannot be detected.

[0009] Therefore, it is urgent to establish an accurate and feasible detection method for the related substances of 2-aminothiophenol to meet the quality control requirements of 2-aminothiophenol and achieve the quality control of drugs such as doripenem and diltiazem. Summary of the Invention

[0010] According to the preparation process of 2-aminothiophenol, the inventors found that 2-aminothiophenol is extremely easy to be oxidized and deteriorated in the air, and there are the following impurities.

[0011]

[0012] Among them, the impurities 2,2'-dithiobis(diphenylamine), 1-phenylthiourea, 2-aminobenzothiazole and aniline all contain amino reaction sites, which can be derivatized and transferred to the active pharmaceutical ingredient, posing risks to the safety and effectiveness of the formulated drugs.

[0013] To solve the quality control problem of 2-aminothiophenol and thus better control the quality of drugs such as doripenem and diltiazem, the present invention provides a detection method for the related substances of 2-aminothiophenol, comprising the following steps:

[0014] (1) Preparation of the test solution: Take an appropriate amount of 2-aminothiophenol, dissolve and dilute it with acetonitrile cooled to -5 to 5°C to prepare a test solution;

[0015] (2) Preparation of the system suitability solution: Take an appropriate amount of 2-aminothiophenol, add hydrogen peroxide solution, and dilute it with acetonitrile to prepare a system suitability solution;

[0016] (3) Chromatographic test: Take the system suitability solution and the test solution, and inject them into a liquid chromatograph respectively, and record the chromatograms.

[0017] Further, in step (3), the chromatographic conditions include:

[0018] Chromatographic column: Packed with octadecylsilane-bonded silica gel or phenyl-bonded silica gel;

[0019] Mobile phase: Mobile phase A: Phosphate solution - disodium ethylenediaminetetraacetate; Mobile phase B: Phosphate solution - disodium ethylenediaminetetraacetate - acetonitrile.

[0020] Further, the phosphate in the mobile phase is selected from one or more of diammonium hydrogen phosphate, dipotassium hydrogen phosphate, and disodium hydrogen phosphate. Preferably, the phosphate is dipotassium hydrogen phosphate.

[0021] Further, the concentration of the phosphate in the mobile phase is 5 mmol / L to 30 mmol / L. Preferably, the concentration of the phosphate is 5 mmol / L.

[0022] Further, the pH of the phosphate solution in the mobile phase is 5.0 - 7.0. Preferably, the pH of the phosphate solution in the mobile phase is 6.0.

[0023] Further, the concentration of disodium ethylenediaminetetraacetate in the mobile phase is 10 mmol / L - 30 mmol / L. Preferably, the concentration of disodium ethylenediaminetetraacetate is 20 mmol / L.

[0024] Further, in the mobile phase A, the ratio (V / V) of the phosphate solution to the disodium ethylenediaminetetraacetate solution is 85 - 95:5 - 15. Preferably, the ratio (V / V) of the phosphate solution to the disodium ethylenediaminetetraacetate solution is 90:10.

[0025] Further, in the mobile phase B, the ratio (V / V / V) of the phosphate solution to the disodium ethylenediaminetetraacetate solution to the acetonitrile solution is 15 - 25:10:65 - 75. Preferably, the ratio (V / V / V) of the phosphate solution to the disodium ethylenediaminetetraacetate solution to the acetonitrile solution is 20:10:70.

[0026] Further, in step (3), the gradient elution conditions of the mobile phase are as follows:

[0027] 。

[0028] Further, in step (3), the gradient elution conditions of the mobile phase are as follows:

[0029] 。

[0030] Further, the chromatographic conditions in step (3) also include:

[0031] Detector: ultraviolet detector;

[0032] Flow rate: 0.5 ml / min - 1.5 ml / min; Preferably, the flow rate is 1.0 ml / min;

[0033] Column temperature: 10 - 40 °C; Preferably, the column temperature is 20 - 40 °C;

[0034] Detection wavelength: 260 nm - 290 nm; Preferably, the detection wavelength is 278 nm;

[0035] Injection volume: 10 μl;

[0036] Quantification method: peak area normalization method.

[0037] The detection method for related substances of 2-aminothiophenol provided by the present invention can detect the impurities contained in 2-aminothiophenol. The impurities are selected from one or more of 2,2'-dithiobis(diphenylamine), 1-phenylthiourea, 2-aminobenzothiazole, and aniline.

[0038] The detection method for related substances of 2-aminothiophenol provided by the present invention has good applicability and is suitable for the quality control of 2-aminothiophenol, and is also suitable for the quality control of dolutegravir and diltiazem.

[0039] Beneficial effects

[0040] The inventor of the present invention found that 2-aminothiophenol contains a mercapto group and is prone to complex with metal ions in the chromatographic column tube wall, resulting in poor main peak shape. The present invention uses a chromatographic column filled with octadecylsilyl-bonded silica gel or phenyl-bonded silica gel, and uses dipotassium hydrogen phosphate as mobile phase A and a mixed solution of dipotassium hydrogen phosphate and acetonitrile as mobile phase B. A certain concentration of metal chelating agent disodium ethylenediaminetetraacetate is added to both mobile phases AB, which can shield metal ions and optimize the peak shape of 2-aminothiophenol.

[0041] The inventor of the present invention found that using acetonitrile cooled to -5 to 2°C as the solvent for sample preparation can improve the step peak caused by continuous oxidation of the main component, and optimize the peak shapes of 2-aminothiophenol and its oxidized impurity 2,2'-dithiobis(diphenylamine). It solves the problem that the detected amount of the oxidized impurity 2,2'-dithiobis(diphenylamine) is not reproducible under normal temperature solvent conditions, and the method has good precision.

[0042] The present invention does not require a reference substance. By a simple operation of degrading the material, 2,2'-dithiobis(diphenylamine) is obtained as a system suitability solution for the localization of 2,2'-dithiobis(diphenylamine), which has strong specificity and low cost.

[0043] The present invention solves the deficiencies existing in the prior art and provides a reverse-phase HPLC determination method, which can realize the inspection of related substances of 2-aminothiophenol. The method has good specificity, linearity, precision, sensitivity, precision, and durability. By an oxidative destruction test, the impurity 2,2'-dithiobis(diphenylamine) is located, and the accurate localization and quantification of 2,2'-dithiobis(diphenylamine) are achieved. It can be used for the quality control of 2-aminothiophenol and meet the quality control requirements of 2-aminothiophenol. Description of the drawings

[0044] Figure 1 Chromatograms of the test solution of Column 1 and Column 2 selected for the method of related substances of 2-aminothiophenol in Example 2.

[0045] Figure 2 Chromatogram of the test solution of Column 3 selected for the method of related substances of 2-aminothiophenol in Example 2.

[0046] Figure 3 Chromatogram of the test solution for the related substances method of 2-aminothiophenol in Example 2 using Column 4.

[0047] Figure 4 Chromatogram of the test solution for the related substances method of 2-aminothiophenol in Example 3 using Mobile Phase A.

[0048] Figure 5 Chromatogram of the test solution for the related substances method of 2-aminothiophenol in Example 4 using Mobile Phase A.

[0049] Figure 6 Overlap diagram of the precision test for the related substances of 2-aminothiophenol in Example 4.

[0050] Figure 7 Chromatogram of the test solution prepared with the solvent at room temperature for the related substances test of 2-aminothiophenol in Example 5.

[0051] Figure 8 Chromatogram of the blank solvent interference test in Example 6.

[0052] Figure 9 Chromatogram of the resolution solution test for the related substances of 2-aminothiophenol in Example 7.

[0053] Figure 10 Chromatogram of the system suitability test for the related substances test of 2-aminothiophenol in Example 8.

[0054] Figure 11 Linear graph of the related substances of 2-aminothiophenol in Example 9.

[0055] Figure 12 Chromatogram of the detection limit solution of 2-aminothiophenol in Example 10.

[0056] Figure 13 Chromatogram of the detection limit solution of 1-phenylthiourea, aniline, 2-aminobenzothiazole, and 2,2'-dithiobis(diphenylamine) in Example 10.

[0057] Figure 14 Chromatogram of the quantitation limit solution of 2-aminothiophenol in Example 10.

[0058] Figure 15 Chromatogram of the quantitation limit solution of 1-phenylthiourea, aniline, 2-aminobenzothiazole, and 2,2'-dithiobis(diphenylamine) in Example 10.

[0059] Figure 16 Overlap diagram of the precision test for the related substances of 2-aminothiophenol in Example 11.

[0060] Figure 17 Overlapping chromatogram of the test solution at a column temperature of 20 - 30 °C for Example 12.

[0061] Figure 18 Chromatogram of the test solution at a column temperature of 45 °C for Example 12

[0062] Figure 19 Overlapping chromatogram of the test solution at different solvent temperatures for Example 12.

[0063] Figure 20 Chromatogram of the test solution at different mobile phase pH values (pH 4.6) for Example 12.

[0064] Figure 21 Chromatogram of the test solution at different mobile phase pH values (pH 7.5) for Example 12. Detailed implementation manners

[0065] To facilitate those skilled in the art to understand the content of the present invention, the specific embodiments of the present invention are described in detail below. It should be noted that the embodiments described below are exemplary and are only used to explain the present invention and should not be construed as a limitation to the present invention.

[0066] Example 1 Preparation of solutions

[0067] Preparation of the test solution: Take 30 mg of 2-aminothiophenol, place it in a 25 ml volumetric flask, dissolve it with a solvent and dilute to the mark, and shake well.

[0068] Preparation of the system suitability solution: Take about 30 mg of 2-aminothiophenol, place it in a 25 ml volumetric flask, add 0.2 ml of 30% hydrogen peroxide solution, dilute to the mark with acetonitrile, shake well, and let it stand at room temperature for 20 minutes.

[0069] Preparation of the impurity stock solution: Take appropriate amounts of 2,2'-dithiobis(diphenylamine), 1-phenylthiourea, 2-aminobenzothiazole, and aniline, dissolve them separately with acetonitrile and dilute to make solutions containing about 0.6 mg of each impurity per 1 ml as the impurity stock solutions.

[0070] Preparation of the resolution solution: Take appropriate amounts of 2-aminothiophenol and each impurity stock solution, dissolve them with acetonitrile and dilute to make a solution containing about 1.2 mg of 2-aminothiophenol and about 1.2 μg of each impurity per 1 ml as the resolution solution.

[0071] Example 2 Selection of chromatographic conditions

[0072] Chromatographic column 1: Filled with phenyl-bonded silica gel

[0073] Chromatographic column 2: Filled with octadecylsilyl-bonded silica gel

[0074] Chromatographic column 3: Packed with octylsilyl silica gel

[0075] Chromatographic column 4: Packed with biphenylsilyl silica gel

[0076] Take 10 μl of the test solution prepared according to Example 1, inject it into the liquid chromatograph under different chromatographic column conditions, and record the chromatogram.

[0077] Results: Under chromatographic columns 1 and 2, the peak shapes of the main component and the degradation impurity 2,2'-dithiobis(diphenylamine) are both good, and there are no interfering peaks near the two peaks, indicating good method specificity. See Appendix Figure 1 , under chromatographic columns 3 and 4, the peak shape of the degradation impurity 2,2'-dithiobis(diphenylamine) is poor. See Appendix Figure 2 and Appendix Figure 3 . Therefore, the chromatographic column is determined to be packed with phenylsilyl silica gel or octadecylsilyl silica gel.

[0078] Example 3 Mobile phase selection

[0079] Mobile phase A: 10 mmol / L dipotassium hydrogen phosphate solution (adjusted to pH 6.0 with phosphoric acid)

[0080] Mobile phase B: Acetonitrile

[0081] Gradient table

[0082] .

[0083] Take 10 μl of the test solution prepared according to Example 1, inject it into the liquid chromatograph, and record the chromatogram.

[0084] Results: The retention and peak shape of the 2-aminothiophenol peak are good. Under these chromatographic column and mobile phase conditions, when injecting multiple samples, the peak shape of the 2-aminothiophenol peak deteriorates and shoulders appear. After flushing with an acidic mobile phase and then injecting the sample, the peak shape improves. However, when injecting multiple samples continuously, the peak shape still deteriorates. See Appendix Figure 4 , adding a metal chelating agent to the mobile phase can improve the peak shape of the 2-aminothiophenol peak.

[0085] Example 4 Mobile phase selection

[0086] Screen according to the following chromatographic conditions as the reference conditions:

[0087] Mobile phase A: 5 mmol / L dipotassium hydrogen phosphate solution (adjusted to pH 6.0 with phosphoric acid) - 20 mmol / L disodium ethylenediaminetetraacetate solution (90∶10)

[0088] Mobile phase B: 5 mmol / L dipotassium hydrogen phosphate solution (adjusted to pH 6.0 with phosphoric acid) - 20 mmol / L disodium ethylenediaminetetraacetate solution - acetonitrile (20∶10∶70)

[0089] Gradient table

[0090] 。

[0091] Take 10 μl of the test solution and inject it into the liquid chromatograph, and record the chromatogram.

[0092] Result: The retention time of the main peak is 12.232 minutes, and the retention time of the impurity 2,2'-dithiobis(diphenylamine) peak is 28.021 minutes. The shapes of the two chromatographic peaks are good. See attachment Figure 5 。Inject multiple needles continuously, and the peak shapes are still good. See attachment Figure 6 。

[0093] Example 5 Solvent Selection

[0094] 2-aminothiophenol is sensitive to air and is easily oxidized. At room temperature, when the test solution is prepared, the oxidation process in the solution is always ongoing, resulting in a step peak between 2-aminothiophenol and the oxidized impurity 2,2'-dithiobis(diphenylamine). See attachment Figure 7 , and the test solution is freshly prepared before use. The reproducibility of the detected amount of oxidized impurities is still poor. Therefore, the sample is dissolved in a pure organic solvent without water, and the organic solvent is placed in a low-temperature environment in advance. That is, acetonitrile cooled to -5 to 2 °C is used as the solvent for sample preparation. As a result, the detected amount of oxidized impurities is lower than that under the room-temperature solvent, and the reproducibility is good. The results are shown in Table 1.

[0095] Table 1 Inspection results of related substances of 2-aminothiophenol at different solvent temperatures

[0096] 。

[0097] Example 6 Solvent Interference Test

[0098] Precisely measure 10 μl of the solvent and inject it into the liquid chromatograph, and record the chromatogram. The details are shown in attachment Figure 8 , and the blank solvent elutes at retention times of 2.585 minutes and 64.323 minutes respectively, without interfering with the determination of the related substances of this product.

[0099] Example 7 Specificity Test - Resolution Test

[0100] Take 10 μl of the resolution solution and the localization solution respectively and inject them into the liquid chromatograph, and record the chromatogram. The minimum resolution between 2-aminothiophenol and the adjacent impurity peak and between each impurity peak is 5.34, and the separation is good. There is no interference peak near 2,2'-dithiobis(diphenylamine). The specific results are shown in Table 2 and attachment Figure 9 。

[0101] Table 2 Results of peak localization and resolution test

[0102] 。

[0103] Example 8 System Suitability Test

[0104] Preparation of the system suitability test solution: Weigh an appropriate amount of 2-aminothiophenol, add 30% hydrogen peroxide solution at 0.8% of the final volume, and dilute with acetonitrile to make a solution containing about 1.2 mg per 1 ml. Shake well and let stand at room temperature for 20 minutes.

[0105] Inject 10 μl of the system suitability solution into the liquid chromatograph and record the chromatogram. The results are shown in the appendix Figure 10 。

[0106] Results: In the chromatogram of the system suitability solution, the retention time of the main peak is 12.093 minutes, and the retention time of 2,2'-dithiobis(diphenylamine) is 32.577 minutes. The peak shape is good and easy to identify, indicating good method specificity.

[0107] Example 9 Linearity Test

[0108] 2-aminothiophenol linear stock solution: Weigh accurately about 30 mg of 2-aminothiophenol, place it in a 25-ml volumetric flask, dilute to the mark with acetonitrile (-5 to 2 °C), and shake well to obtain the linear stock solution.

[0109] Accurately pipette 0.1 ml, 0.2 ml, and 1 ml respectively into 3 different 10-ml volumetric flasks, dilute to the mark with acetonitrile (-5 to 2 °C), and shake well to obtain linear solution 1, linear solution 2, and linear solution 3 respectively.

[0110] Accurately weigh about 15 mg and 36 mg of 2-aminothiophenol respectively, place them in two different 25-ml volumetric flasks, dilute to the mark with acetonitrile (-5 to 2 °C), and shake well to obtain linear solution 4 and linear solution 5 respectively.

[0111] Quantitation limit solution: Accurately weigh about 30 mg of 2-aminothiophenol, place it in a 25-ml volumetric flask, dilute to the mark with acetonitrile (-5 to 2 °C), accurately pipette 0.15 ml, place it in a 100-ml volumetric flask, dilute to the mark with acetonitrile (-5 to 2 °C), and shake well.

[0112] Accurately pipette 10 μl of each of the above series of solutions, inject them into the liquid chromatograph respectively, record the chromatogram, plot a curve with the peak area against the concentration, and calculate the regression equation and correlation coefficient by the least squares method. The results are shown in Table 3 and the appendix Figure 11 As shown, combined with the results of the quantitation limit test, the linearity of the related substances of 2-aminothiophenol is good.

[0113] Table 3 Results of the linearity test for the related substances of 2-aminothiophenol

[0114] 。

[0115] Example 10 Limit of Quantification and Limit of Detection Tests

[0116] Appropriately weigh each compound and dilute with acetonitrile cooled to -5 to 2°C to prepare solutions of different concentrations. Accurately pipette 10 μl each and inject into the liquid chromatograph, record the chromatogram, until the peak response value measured is not less than 10 times and 3 times the height of the noise signal, which are the limits of quantification and detection of each compound. The results are shown in Table 4, Table 5 and Appendix Figures 12 to 15 。

[0117] Table 4 Results Table of Detection Limit of Related Substances of 2-Aminothiophenol

[0118]

[0119] Table 5 Results Table of Limit of Quantification of Related Substances of 2-Aminothiophenol

[0120] 。

[0121] Example 11 Precision Test

[0122] Preparation of test solution: freshly prepared before use. Weigh appropriately 2-aminothiophenol and dilute with acetonitrile cooled to -5 to 2°C to prepare a solution containing about 1.2 mg per 1 ml as the test solution. Prepare 6 portions of the test solution in parallel.

[0123] Accurately pipette 10 μl each of the test solution and inject into the liquid chromatograph respectively, record the chromatogram. The results are shown in Table 6 and Appendix Figure 16 , the detected amounts of 2,2'-dithiobis(diphenylamine) in the 6 determinations are basically the same (1.28% - 1.30%), the detected amounts of other maximum single impurities are the same (0.10% - 0.11%), and the detected amounts of total impurities are the same (1.46% - 1.49%). The results show that the precision test results are good.

[0124] Table 6 Results of Precision Test

[0125] 。

[0126] Example 12 Robustness Test

[0127] Accurately pipette 10 μl each of the test solution and inject into the liquid chromatograph respectively, record the chromatogram. On the basis of the established chromatographic conditions, use mobile phases with different column temperatures, different solvent temperatures, and different pH values as shown in Table 7 to determine the related substances of this product. The results are as Figures 17 to 21As shown, within the range of column temperature from 20 to 40 °C, solvent temperature from -5 to 5 °C, and mobile phase pH value from 5.0 to 7.0, the peak shape of 2-2'-dithiobis(diphenylamine) is good. The detection amounts of 2-2'-dithiobis(diphenylamine), other maximum single impurities, and total impurities are calculated respectively by the peak area normalization method. The impurity spectra are basically the same, the determination results are basically consistent, and the durability of the method is good.

[0128] Under the conditions of column temperature 45 °C, mobile phase pH values 4.6 and 7.5, the peak shapes of 2-2'-dithiobis(diphenylamine) are both poor, and the method is not applicable.

[0129] Table 7 Durability of the related substances inspection method for 2-aminobenzenethiol

[0130] 。

Claims

1. A method for detecting related substances of 2-aminothiophenol, characterized in that, It includes the following steps: (1) Preparation of the test solution: Take an appropriate amount of 2-aminothiophenol, dissolve and dilute it with acetonitrile cooled to -5 to 5°C to prepare a test solution. (2) Preparation of the system suitability solution: Take an appropriate amount of 2-aminothiophenol, add hydrogen peroxide solution, and dilute with acetonitrile to prepare a system suitability solution. (3) Chromatographic test: Take the system suitability solution and the test solution, and inject them into the liquid chromatograph respectively, and record the chromatogram.

2. The detection method of 2-aminothiophenol related substances according to claim 1, characterized in that, In step (3), the chromatographic conditions include: Chromatographic column: Packed with octadecylsilane-bonded silica gel or phenyl-bonded silica gel. Mobile phase: Mobile phase A: Phosphate solution - disodium ethylenediaminetetraacetate; Mobile phase B: Phosphate solution - disodium ethylenediaminetetraacetate - acetonitrile.

3. The detection method of 2-aminothiophenol related substances according to claim 2, characterized in that, The phosphate in the mobile phase is selected from one or more of diammonium hydrogen phosphate, dipotassium hydrogen phosphate, and disodium hydrogen phosphate.

4. The detection method of 2-aminothiophenol related substances according to claim 3, characterized in that, The phosphate is dipotassium hydrogen phosphate.

5. The detection method for related substances of 2-aminothiophenol according to claim 2, characterized in that, In the mobile phase A, the ratio of the phosphate solution - disodium ethylenediaminetetraacetate solution (V / V) is 85 - 95∶5 - 15.

6. The detection method for related substances of 2-aminothiophenol according to claim 2, wherein In the mobile phase B, the ratio of the phosphate solution - disodium ethylenediaminetetraacetate solution - acetonitrile solution (V / V / V) is 15 - 25∶10∶65 - 75.

7. The detection method of the related substances of 2-aminothiophenol according to claim 2, characterized in that, The mobile phase gradient elution conditions are as follows: 。 8. The detection method of the related substances of 2-aminothiophenol according to claim 7, wherein, The mobile phase gradient elution conditions are as follows: 。 9. The detection method of the related substances of 2-aminothiophenol according to claim 2, characterized in that, The chromatographic conditions described in step (3) also include: Detector: Ultraviolet detector. Flow rate: 0.5 ml / min to 1.5 ml / min; preferably, the flow rate is 1.0 ml / min. Column temperature: 10 to 40°C; preferably, the column temperature is 20 to 40°C. Detection wavelength: 260 nm to 290 nm; preferably, the detection wavelength is 278 nm. Injection volume: 10 μl. Quantification method: Peak area normalization method.

10. The method for detecting related substances of 2-aminothiophenol according to any one of claims 1-9 can detect the impurities contained in 2-aminothiophenol, and the impurities are selected from one or more of 2,2'-dithiobis(diphenylamine), 1-phenylthiourea, 2-aminobenzothiazole, and aniline.

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