Method for detecting residual solvents in dapsig Heg raw material medicine

Abstract

The application discloses a method for detecting residual solvents in daprodustex raw medicine, characterized in that the method quantitatively detects residual solvents in daprodustex raw medicine by high performance liquid chromatography; the high performance liquid chromatography conditions adopt mixed mobile phases of mobile phase A and mobile phase B to perform gradient elution on the daprodustex raw medicine to be measured; the mobile phase A is 10 mM potassium dihydrogen phosphate in 0.1% phosphoric acid aqueous solution; the mobile phase B is a methanol solution; the initial proportion of the mobile phase A and the mobile phase B in the elution process is 100% mobile phase A and 0% mobile phase B; after the gradient elution, the chromatogram of the daprodustex raw medicine to be measured is measured, and the content of the residual solvents in the daprodustex raw medicine to be measured is calculated by the peak area according to the external standard method with the chromatogram of a standard sample.

Description

TECHNICAL FIELD

[0001] The present application relates to a detection method for residual solvents in a drug, in particular to a detection method for residual solvents in dapsatex bulk drug. BACKGROUND

[0002] Dapsatex is an important bulk drug, and acetic acid is often used as a solvent or reaction medium during its production process. However, the residual acetic acid may adversely affect the quality, safety and effectiveness of the drug. Therefore, accurately detecting the residual amount of acetic acid in dapsatex bulk drug is a key link to ensure the quality of the drug.

[0003] Currently, the detection methods for residual solvents mainly include gas chromatography (GC) and high performance liquid chromatography (HPLC). Although gas chromatography has high sensitivity, it has limitations for some thermally unstable or difficult to vaporize compounds. In contrast, high performance liquid chromatography (HPLC) has the advantages of high separation efficiency, high detection sensitivity, simple operation, etc., and is suitable for the detection of various organic solvents.

[0004] In the prior art, although there are various methods for detecting residual solvents in dapsatex, these methods often have problems such as complex operation, insufficient sensitivity (recovery rate less than 95%) or poor reproducibility. For example, although the traditional headspace gas chromatography can detect residual acetic acid, it requires a complex sample processing process and has high requirements for operating conditions. In addition, the sensitivity and accuracy of some methods are difficult to meet the requirements of quality control when detecting low-concentration residual solvents.

[0005] Therefore, it is of great significance to develop a detection method with high efficiency, sensitivity, simple operation and good reproducibility for the quality control of dapsatex bulk drug. SUMMARY

[0006] The present application provides a high performance liquid chromatography analysis method for detecting the content of residual solvents in dapsatex bulk drug, aiming to solve the problems of complex operation, insufficient sensitivity and poor reproducibility in existing detection methods, so as to realize rapid, accurate and sensitive detection of the residual amount of acetic acid in dapsatex bulk drug, and significantly improve the accuracy and reliability of drug quality control.

[0007] According to a preferred embodiment of the present application, the present application provides a detection method for residual solvents in dapsatex bulk drug, which uses high performance liquid chromatography to quantitatively detect residual solvents in dapsatex bulk drug:

[0008] The high performance liquid chromatography condition adopts mixed mobile phase of mobile phase A and mobile phase B for gradient elution of the dapsigargin raw material to be tested; the mobile phase A is 10 mM potassium dihydrogen phosphate in 0.1% phosphoric acid aqueous solution; the mobile phase B is a methanol solution; the initial proportion of the mobile phase A and the mobile phase B in the elution process is 100% mobile phase A and 0% mobile phase B; and the specific gradient elution process is as follows:

[0009] In 0-5 minutes, the initial proportion of the mobile phase A and the mobile phase B is kept unchanged;

[0010] In 5-8 minutes, the proportion of the mobile phase A and the mobile phase B is uniformly changed to 5:95;

[0011] In 8-15 minutes, the proportion of the mobile phase A and the mobile phase B is kept unchanged at 5:95;

[0012] In 15-17 minutes, the proportion of the mobile phase A and the mobile phase B is changed from 5:95 to the initial proportion;

[0013] In 17-22 minutes, the initial proportion of the mobile phase A and the mobile phase B is kept unchanged;

[0014] The chromatogram of the dapsigargin raw material to be tested is measured, and the content of the residual solvent in the dapsigargin raw material to be tested is calculated by the peak area according to the chromatogram of the standard sample by the external standard method.

[0015] According to an embodiment of the present application, the preparation method of the mobile phase A is as follows: 1.36 g of potassium dihydrogen phosphate is weighed into 1000 mL of water, 1 mL of phosphoric acid is added, ultrasonic dissolution is performed, filtration is performed, and ultrasonic degassing is performed to obtain the mobile phase A.

[0016] According to an embodiment of the present application, the preparation method of the mobile phase B is as follows: 1000 mL of a methanol solution is placed in a mobile phase bottle, and ultrasonic degassing is performed to obtain the mobile phase B.

[0017] According to an embodiment of the present application, the high performance liquid chromatography condition meets at least one of the following:

[0018] The length of the chromatographic column is 150 mm;

[0019] The inner diameter of the chromatographic column is 4.6 mm;

[0020] The particle size of the chromatographic column is 5 μm;

[0021] The flow rate of the chromatographic column is 0.9-1.1 mL / min;

[0022] The column temperature of the chromatographic column is 30-40 °C;

[0023] The detection wavelength of the chromatographic column is 190-400 nm;

[0024] The injection volume of the chromatographic column is 5-15 μL.

[0025] According to an embodiment of the present application, the high-performance liquid chromatography conditions include: a detection wavelength of 208-210 nm; and an injection volume of 10 μL.

[0026] Technical effects:

[0027] The core content of the present application includes the following aspects:

[0028] 1. High sensitivity and good reproducibility of detection

[0029] The present application optimizes the chromatographic conditions of high-performance liquid chromatography (HPLC), including the composition of the mobile phase, the flow rate, the column temperature, the detection wavelength, and other parameters, to achieve efficient separation and detection of acetic acid. Specifically, by using a specific type of chromatographic column and a mobile phase system, good separation of acetic acid from other components can be achieved in a short time, while ensuring the sensitivity and reproducibility of the detection.

[0030] 2. High accuracy and better reliability of detection

[0031] The present application provides a simple and efficient sample processing method, which can directly determine the acetic acid residual amount in dapsigHat raw drug without complex pretreatment steps. By optimizing the sample dissolution and filtration conditions, it ensures that the acetic acid in the sample can be completely released and enter the chromatographic system, thereby improving the accuracy and reliability of the detection.

[0032] 3. Actual application value

[0033] The detection method of the present application is simple, fast and efficient, and is suitable for daily detection in large-scale production and quality control. Its high sensitivity and high reproducibility can effectively avoid the risk of drug quality caused by acetic acid residues, ensuring the safety and effectiveness of dapsigHat raw drug, and providing a reliable technical means for quality control of pharmaceutical production enterprises. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 is a blank solution chromatogram;

[0035] Figure 2 is an acetic acid positioning solution chromatogram;

[0036] Figure 3 is a reference solution chromatogram;

[0037] Figure 4 is a sample solution chromatogram;

[0038] Figure 5 is a detection limit chromatogram;

[0039] Figure 6 is a quantitative limit solution chromatogram;

[0040] Figure 7 is an acetic acid linear equation graph;

[0041] Figure 8 A synthetic route map of the self-made dapsigHat sample is shown. DETAILED DESCRIPTION

[0042] The following description is provided to enable any person skilled in the art to practice the present application. The preferred embodiments in the following description are only examples of the present application and various modifications can be made by those skilled in the art without departing from the spirit and scope of the present application. The basic principles defined in the following description can be applied to other embodiments, variations, improvements, equivalents and other technical solutions without departing from the spirit and scope of the present application.

[0043] In the embodiments of the present application, the high performance liquid chromatograph (four-element pump, degassing unit, DAD detector, column oven, automatic sampler, system monitor CDS2) (Agilent Technology Co., Ltd.) is used; methanol (chromatographic pure, Shanghai Adamas Beta Chemical Reagents Co., Ltd.); potassium dihydrogen phosphate (chromatographic pure, Shanghai Adamas Beta Chemical Reagents Co., Ltd.); tetrahydrofuran (chromatographic pure, Shanghai Adamas Beta Chemical Reagents Co., Ltd.); acetic acid (chromatographic pure, Shanghai Adamas Beta Chemical Reagents Co., Ltd.);

[0044] Reference Figure 8 As preferred, the dapsigHat sample can be obtained by self-made way or purchased from the market.

[0045] In a preferred embodiment, the self-made dapsigHat sample used has the following synthetic route:

[0046] S1, preparation of intermediate 1:

[0047] Malonic acid (31.2 g) is added to a 1L three-necked flask, tetrahydrofuran 1 (347 g / 390 ml) is added, stirred and dissolved, nitrogen is flushed in, and then cooled to-20℃. Dicyclohexyl carbodiimide (DCC) (124 g) is dissolved in tetrahydrofuran 2 (333 g / 374 mL), slowly added to the reaction solution, and the system is kept below-5℃. After the addition is completed, slowly warm to room temperature 20~30℃. Keep 20~30℃ for 3 hours. A large amount of white solid will precipitate in the reaction.

[0048] After the reaction is completed, filter, get the filtrate, and rinse the solid with tetrahydrofuran 3 (55 g / 62 mL) and tetrahydrofuran 4 (55 g / 62 mL) twice. Concentrate the filtrate and dry it with an oil pump to get yellow crude product.

[0049] The yellow crude was added to the reaction flask, ethanol 1 (403 g / 510 mL) was added to slurry, after stirring for five minutes, the ethanol was brought to reflux, the ethanol was kept at reflux for half an hour, then slowly brought to room temperature, stirred at room temperature for fifteen minutes, then centrifuged. The solid was washed with cold ethanol 2 (25 g / 31 mL) and cold ethanol 3 (25 g / 31 mL) twice. The solid was dried using an oil pump to get the product 49.0 g (the difference in mass was less than 0.1 g twice), HPLC: 99.2%, ethanol content: 0.02%.

[0050] Preparation of S2, Intermediate 2:

[0051] Intermediate 1 (34.0 g) was added to the reaction flask, dichloromethane (7.95 kg) was added to dissolve, then DIPEA (21.2 g) was added slowly, after the addition was completed, ethyl isocyanoacetate (12.7 g) was added dropwise, after the addition was completed, the reaction was stirred at room temperature for 16 hours. HPLC monitoring, the remaining raw material was less than 1%.

[0052] After the reaction was completed, the temperature was lowered to 5-10°C in an ice water bath. Concentrated hydrochloric acid (18.9 g / 16 mL) was added to water (176 g) to prepare a 1 mol / L hydrochloric acid solution, after the temperature was lowered to room temperature, it was slowly added to the reaction solution, keeping the temperature below 20°C, the reaction was quenched, after the dropwise addition was completed, it was stirred for half an hour. Then the layers were separated, the organic phase was dried with sodium sulfate, filtered, and the filtrate was concentrated and dried. The solid was added to n-heptane 1 (246 g / 360 mL) and stirred, then heated to reflux. After refluxing for 15 minutes, the temperature was slowly lowered to room temperature. Continue stirring for fifteen minutes, then centrifuge and filter to obtain a solid, which was washed with n-heptane 2 (33 g / 48 mL) and n-heptane 3 (33 g / 48 mL) twice, and dried with an oil pump to obtain a white solid product 32.6 g (the difference in mass was less than 0.1 g twice), HPLC: 99.6%.

[0053] Preparation of crude product:

[0054] Sodium hydroxide (11.4 g) was first dissolved in water 1 (300 mL) to prepare a sodium hydroxide solution, which was cooled to room temperature and prepared. Ethanol (150 mL) was added to the reaction flask, intermediate 2 (30 g) was added, stirred at room temperature, then the prepared sodium hydroxide aqueous solution was slowly added, after the addition was completed, the reaction was stirred at room temperature for 16 hours. HPLC monitoring, the remaining raw material was less than 0.1%.

[0055] After the reaction is completed, the ethanol is removed until the weight of the reaction liquid is less than the total mass of water plus hydroxide plus intermediate 2 or the volume is less than half of the reaction volume, and water 2 (120 mL) is added. Concentrated hydrochloric acid (28.5 g) is added to water 3 (85.5 mL) to prepare 3 mol / L hydrochloric acid for standby. The reaction liquid is reduced to 0-10°C, and 3 mol / L hydrochloric acid is slowly dropped, and the system temperature is kept below 20°C. After the dropping is completed, continue to stir for half an hour. Filter to obtain a white solid, and rinse the solid with water 4 (60 mL) and water 5 (60 mL) twice. Add water 6 (600 g) to the solid, keep the system at 25-30°C, continue to stir for one hour, then centrifuge, rinse the solid with water 7 (60 mL) and water 8 (60 mL) twice, then rinse with n-heptane 1 (41 g / 60 mL) and n-heptane 2 (41 g / 60 mL) twice. Vacuum drying, then add n-heptane 3 (197 g / 288 mL) / ethyl acetate 1 (65 g / 72 mL)=1:4 mixed solvent (12V) to the dried solid, and slurry at 20-30°C for 0.5 hours, then centrifugal filtration, rinse the solid with n-heptane (32.7 g / 48 mL) / EA (10.8 g / 12 mL)=1:4 mixed solvent (2V, 60 mL) twice, and vacuum pump dry the solid to obtain a white solid product 25.4 g, HPLC: 99.8%, single impurity less than 0.1%.

[0056] Dapstat product preparation:

[0057] Add dapstat crude product (24.0 g) to the reaction bottle, add acetic acid 1 (302.4 g / 288 mL), stir and heat to acetic acid reflux, the substrate is gradually dissolved, and the system is gradually clarified. Continue to stir for fifteen minutes, there is a small amount of insoluble material in the system, filter out the insoluble material while hot, and then naturally reduce the filtrate to room temperature. A large amount of solid is precipitated. Filter and centrifuge to obtain a solid, rinse the solid with acetic acid 2 (50.4 g / 48 mL) and acetic acid 3 (50.4 g / 48 mL) twice, and then vacuum dry the solid to constant weight to obtain a product 21.0 g, purity 99.9%, maximum single impurity less than 0.1%, and acetic acid residue ≤0.5%.

[0058] In the embodiment of the application, the chromatographic conditions are: the chromatographic column is Shimadzu ShimNex HE C18-AQ column; gradient elution is carried out using mobile phase A and mobile phase B as mixed mobile phases; the mobile phase A is 8-12 mM potassium dihydrogen phosphate in 0.08-0.12% phosphoric acid aqueous solution; the mobile phase B is methanol solution; the initial ratio of the mobile phase A and the mobile phase B in the elution process is 100% mobile phase A and 0% mobile phase B; the specific gradient elution process is as follows with reference to Table 1 below:

[0059] The initial proportion of the mobile phase A and the mobile phase B is kept unchanged within 0-5 minutes;

[0060] The proportion of the mobile phase A and the mobile phase B is uniformly changed to 5:95 within 5-8 minutes;

[0061] The proportion of the mobile phase A and the mobile phase B is kept unchanged at 5:95 within 8-15 minutes;

[0062] The proportion of the mobile phase A and the mobile phase B is changed from 5:95 to the initial proportion within 15-17 minutes;

[0063] The proportion of the mobile phase A and the mobile phase B is kept unchanged at the initial proportion within 17-22 minutes.

[0064] As preferred, the detection wavelength is 208-212 nm, the flow rate is 0.9-1.1 mL / min, the column temperature is 30-40 ℃, 5-15 μL of the sample solution and the control solution is precisely taken and injected into the liquid chromatograph, and the chromatogram is recorded.

[0065] Table 1: System process

[0066]

[0067] In the embodiment of the present application, 20-30 mg of daprodustat raw material is precisely weighed, placed in a sample vial, 0.8-1.2 mL of tetrahydrofuran is added, and ultrasonic dissolution is performed. After cooling to room temperature, shaking is performed, filtration is performed, and the filtrate is taken as the sample solution.

[0068] In the embodiment of the present application, the control solution is prepared as follows: an appropriate amount of acetic acid control is precisely weighed, tetrahydrofuran is added to perform ultrasonic dissolution, and quantitative dilution is performed to prepare a solution containing about 20-30 mg of acetic acid per 0.8-1.2 mL, which is used as the control solution.

[0069] In the embodiment of the present application, the control solution is prepared as follows: 0.25-0.5 mL of the control solution is precisely taken and placed in a 50-100 mL volumetric flask containing an appropriate amount of diluent, diluent is added to reach the calibration mark, shaking is performed, and a solution containing about 100-150 μg of acetic acid per 0.8-1.2 mL is prepared, which is used as the control solution.

[0070] In the embodiment of the present application, the method for determining the content is as follows: the sample solution and the control solution are precisely taken and injected into the liquid chromatograph, the chromatogram is recorded, and the peak area is calculated by the external standard method.

[0071] Example 1: Specificity

[0072] Blank / diluent: tetrahydrofuran.

[0073] Take the blank solution, inject into the liquid chromatograph, record the chromatogram; the chromatogram is as shown in Figure 1 .

[0074] Accurately weigh 249.2 mg of acetic acid reference substance into a 10 mL volumetric flask, dilute to the mark with diluent, as the acetic acid reference substance stock solution.

[0075] Take 1 ml of acetic acid reference substance stock solution into a 10 mL volumetric flask, dilute to the mark with diluent, as the acetic acid positioning solution, inject into the liquid chromatograph, record the chromatogram; the chromatogram is as shown in Figure 2 .

[0076] Take 0.5 mL of the reference substance stock solution into a 100 mL volumetric flask, dilute to the mark with diluent, as the reference substance solution, inject into the liquid chromatograph, record the chromatogram; the chromatogram is as shown in Figure 3 .

[0077] Accurately weigh 24.5 mg of dapsigillide sample, prepare into sample solution, inject into the liquid chromatograph, record the chromatogram; the chromatogram is as shown in Figure 4 .

[0078] Table 2 Specificity results

[0079]

[0080] Reference Figure 4 and Table 2, the results show that under the chromatographic conditions, there is no interference in the blank solution chromatogram at the acetic acid peak position. In the reference substance solution, the minimum separation between acetic acid and adjacent peaks is 2.33. In the sample solution, the minimum separation between acetic acid and its adjacent peaks is 5.09, which meets the separation requirements.

[0081] Example 2: System suitability

[0082] Take the reference substance solution and inject it 5 times in succession, and return to inject 1 needle at the end of the sequence, to investigate the system precision.

[0083] Table 3 System precision results

[0084]

[0085] Referring to Table 3, the results show that the RSD of acetic acid retention time is ≤2%, and the RSD of peak area is all ≤5%, the system precision is good.

[0086] Example 3: Sensitivity investigation

[0087] Step by step dilution of the control solution, to confirm the detection limit and the limit of quantification of acetic acid, and take the limit of quantification solution continuously sample 6 needles, detection limit solution sample continuously sample 3 needles, the signal-to-noise ratio of the limit of quantification should be no less than 10, the signal-to-noise ratio of the detection limit should be no less than 3. The detection limit data is shown in Table 4, the limit of quantification data is shown in Table 5, the detection limit chromatogram is shown in Figure 5 , and the limit of quantification chromatogram is shown in Figure 6 .

[0088] Table 4 Detection limit test data

[0089]

[0090] Table 5 Limit of quantification test data

[0091]

[0092] Example 4: Linearity and range

[0093] Precisely weigh 249.2 mg of acetic acid control into a 10 mL volumetric flask, add tetrahydrofuran to dissolve and dilute to the mark as a control stock solution. Precisely take the control stock solution, prepare a series of gradient concentration solutions, respectively 4%, 10%, 50%, 100%, 150% and 200% of the limit. With the solution concentration as the abscissa, the peak area as the ordinate, linear regression is carried out, and the linear equation is obtained, the results are shown in Table 6. The linear equation is shown in Figure 7 .

[0094] Table 6 Linear test results

[0095]

[0096] The results show that acetic acid in the test concentration of 4.984 μg / mL ~ 249.2 μg / mL, the determination concentration and the peak area show a good linear relationship, which meets the requirements of high performance liquid chromatography for content determination.

[0097] Example 5: Accuracy test

[0098] The control solution, the limit of quantification solution and the 150% solution are the same as the 100%, 4% and 150% linear solutions under the linear and range item of Example 4.

[0099] 150% accuracy solution preparation: precisely weigh 0.0252 g, 0.0244 g and 0.0252 g of dapsigat raw material into liquid phase vials, respectively, add 1 mL of 150% linear solution, ultrasonic to dissolve, and after cooling to room temperature, shake well. Marked as A-150%-1 ~ 3.

[0100] 100% accuracy solution preparation: 0.0247 g, 0.0248 g and 0.0247 g of dapsigillide raw material were precisely weighed into liquid phase vials, 1 mL of 10% linear solution was added, and the solution was dissolved by ultrasonic. After cooling to room temperature, shake well. Marked as A-100%-1-3.

[0101] LOQ accuracy solution preparation: 0.0249 g, 0.0252 g and 0.0245 g of dapsigillide raw material were precisely weighed into liquid phase vials, 1 mL of limit of quantification solution was added, and the solution was dissolved by ultrasonic. After cooling to room temperature, shake well. Marked as A-LOQ-1-3.

[0102] The above reference solution and accuracy solution were injected into the liquid chromatograph, and the chromatogram was recorded to calculate the recovery rate. The results are shown in Table 7.

[0103] Table 7 Acetic acid detection recovery rate

[0104]

[0105] It can be seen that this method makes the final acetic acid detection recovery rate between 95%-105%, so the accuracy is high.

[0106] Example 6: Reproducibility test

[0107] Six sample solutions were prepared respectively for detection, and the detection results are shown in Table 8.

[0108] Table 8 Reproducibility test results

[0109]

[0110] The results show that the RSD% of acetic acid content in the six sample solutions is less than 5%, which meets the requirements of high performance liquid chromatography for content determination.

[0111] Example 7: Solution stability test

[0112] The reference solution and sample solution under the reproducibility test were used for stability investigation, and were detected at 0 h, 8 h, 12 h and 24 h respectively. The test results are shown in Table 9.

[0113] Table 9 Stability results of reference and sample solutions

[0114]

[0115] The results show that after the preparation of the reference solution and the sample solution, the ratio of the peak area of each component to that at 0 h is between 90% and 110% after 24 h at room temperature. The reference solution is stable at room temperature within 24 h.

[0116] Example 8: Durability test

[0117] To investigate the tolerance of the method when the conditions change, a durability test was performed. The chromatographic column temperature (35±5℃), flow rate (1.0±0.1 mL / min), and detection wavelength (210±5 nm) were adjusted, and the control solution and sample solution were injected separately to compare the minimum separation between acetic acid and its adjacent peaks in the sample solution and the content of acetic acid under different parameter conditions.

[0118] The control solution and sample solution used in the repeatability test were used as the control solution and sample solution. 10 μL of each solution was precisely transferred, injected into the liquid chromatograph according to the standard conditions and the changed conditions, and the chromatogram was recorded. The results are shown in Table 10.

[0119] Table 10 Durability test results

[0120]

[0121] The results show that the flow rate is 0.9-1.1 mL / min, the column temperature is 33-37℃, and the detection wavelength is 205-215 nm, which can meet the detection requirements of each component.

[0122] Example 9: Sample detection

[0123] The content of residual solvent acetic acid in multiple batches of dapristat bulk drug produced by the applicant was detected, and the results are shown in Table 11.

[0124] Table 11 Detection results of acetic acid residues in dapristat bulk drug

[0125]

[0126] Those skilled in the art will understand that the embodiments of the application shown in the above description and the accompanying drawings are only examples and do not limit the application. The advantages of the application have been fully and effectively achieved. The function and structural principle of the application has been shown and explained in the embodiments, and the implementation of the application can be any modification or modification without departing from the described principle.

Claims

1. A method for detecting residual acetic acid in dapoxetine raw material, characterized in that, The detection method employs high-performance liquid chromatography (HPLC) for the quantitative detection of residual acetic acid in dapoxetine raw material. The HPLC conditions involve a mixed mobile phase (A and B) for gradient elution of the dapoxetine raw material. Mobile phase A consists of 10 mM potassium dihydrogen phosphate in a 0.1% phosphoric acid aqueous solution; mobile phase B is a methanol solution. The initial ratio of mobile phase A to mobile phase B during elution is 100% mobile phase A and 0% mobile phase B. The chromatographic column used is a Shimadzu ShimNex HE C18-AQ column. The specific gradient elution process is as follows: Within 0 to 5 minutes, the initial ratio of mobile phase A and mobile phase B remains unchanged; Within 5 to 8 minutes, the ratio of mobile phase A to mobile phase B gradually changes to 5:95 at a constant rate. The ratio of mobile phase A to mobile phase B remains constant at 5:95 for 8 to 15 minutes. Within 15 to 17 minutes, the ratio of mobile phase A to mobile phase B gradually changes from 5:95 back to the initial ratio. The ratio of mobile phase A to mobile phase B remains unchanged from the initial ratio for 17 to 22 minutes. The chromatogram of the daprostat raw material to be tested was obtained, and the content of residual acetic acid in the daprostat raw material to be tested was calculated by peak area using the external standard method based on the chromatogram of the standard sample.

2. The method for detecting residual acetic acid in dapoxetine raw material according to claim 1, characterized in that, The preparation method of the mobile phase A is as follows: Weigh 1.36 g of potassium dihydrogen phosphate into 1000 mL of water, add 1 mL of phosphoric acid, sonicate to dissolve, filter through a filter membrane, and then sonicate to degas to obtain the mobile phase A.

3. The method for detecting residual acetic acid in dapoxetine raw material according to claim 1, characterized in that, The preparation method of the mobile phase B is as follows: Take 1000 mL of methanol solution and place it in a mobile phase bottle, then degas it by ultrasonication.

4. The method for detecting residual acetic acid in dapoxetine raw material according to claim 1, characterized in that, The high-performance liquid chromatography conditions meet at least one of the following: the length of the chromatographic column is 150 mm; The inner diameter of the chromatographic column is 4.6 mm; The particle size of the chromatographic column packing material is 5 μm; The flow rate of the chromatographic column is 0.9–1.1 mL / min; The column temperature of the chromatographic column is 30–40°C; The detection wavelength of the chromatographic column is 190–400 nm; The injection volume of the chromatographic column is 5–15 μL.

5. The method for detecting residual acetic acid in dapoxetine raw material according to claim 4, characterized in that, The high-performance liquid chromatography (HPLC) conditions include: a detection wavelength of 208–212 nm and an injection volume of 10 μL.

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