Detection method of pravastatin related substances

Abstract

The invention relates to a method for detecting related substances of pravastatin. The detection method comprises the following steps that a to-be-detected product is detected through a high performance liquid chromatography method, and a filler of a chromatographic column of the liquid chromatography method is ethylidene bridge hybrid particles; according to the high performance liquid chromatography method, brand new five-stage gradient elution is adopted, and a to-be-detected product comprises one or more of pravastatin, pravastatin salt and pravastatin related substances. According to the detection method, effective separation of pravastatin and unknown degradation impurities adjacent to pravastatin and effective separation of an impurity D and unknown impurities adjacent to pravastatin can be achieved at the same time, and accurate detection of pravastatin and the impurity D can be achieved; the separation degree of the impurity B and the impurity E can be improved; the detection method also passes methodology verification, and an effective detection method is provided for the content of the pravastatin related substances.

Description

Technical Field

[0001] The invention belongs to the field of medicine, and particularly relates to a method for detecting pravastatin-related substances. Background Art

[0002] Pravastatin sodium is an HMG-CoA reductase inhibitor used to treat hyperlipidemia and familial hypercholesterolemia. Pravastatin sodium was developed by Daiichi Sankyo Co., Ltd. and has been launched in Japan, the United States, Europe and other countries. The 20mg and 10mg pravastatin sodium tablets produced by Daiichi Sankyo were approved by NMPA (formerly CFDA) and launched in China in January 2004 and February 2004, respectively. The dosage form is tablets. The 40mg pravastatin sodium tablets produced by Daiichi Sankyo were launched in March 2006. In China, pravastatin sodium is included in the 2020 edition of the Chinese Pharmacopoeia, and the dosage forms included include pravastatin sodium tablets and pravastatin sodium capsules. The detection methods of related substances in pravastatin sodium tablets are included in the United States Pharmacopoeia USP 43, the British Pharmacopoeia BP 2021, the Japanese Pharmacopoeia JP 17 and the Chinese Pharmacopoeia ChP2020.

[0003] The impurities listed in the pharmacopoeias of various countries for raw materials are shown in the table below.

[0004] Table 1. Impurities of pravastatin sodium API in various pharmacopoeias

[0005]

[0006]

[0007] Note: The above impurity names refer to BP / EP regulations.

[0008] The detection capability of the impurities specified in the pharmacopoeias of various countries is qualified, but it still cannot meet the detection requirements of all the impurities mentioned above for this product. The types of impurities detected are relatively small, and there is still a poor separation between known impurities and unknown impurities, or between unknown impurities and pravastatin, resulting in inaccurate measurement results of pravastatin and the above-mentioned known impurities. How to accurately determine the content of related substances is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0009] The technical problem to be solved by the present invention is that when detecting pravastatin related substances, some impurities are poorly separated from pravastatin and the impurities are difficult to separate from each other. A detection method for pravastatin related substances is provided, which can simultaneously achieve effective separation of pravastatin and its adjacent unknown impurities, and impurity D and its adjacent unknown impurities. Further, the separation degree of impurity B and impurity E can be improved, thereby improving the accuracy of the content of related substances such as pravastatin, impurity D, impurity B and impurity E; further, the detection method has passed methodological verification.

[0010] The present invention provides a method for detecting pravastatin-related substances, which comprises the following steps: using high performance liquid chromatography to detect a test product, wherein the filler of a chromatographic column of the liquid chromatography is ethylene bridged hybrid (BEH) particles;

[0011] The mobile phase of the high performance liquid chromatography is composed of mobile phase A and mobile phase B;

[0012] The mobile phases A and B are a mixture of water, phosphate buffer and acetonitrile;

[0013] In the mobile phases A and B, the pH value of the phosphate buffer is 6.8-7.2;

[0014] The high performance liquid chromatography method adopts a five-stage gradient elution:

[0015]

[0016]

[0017] The elution duration is the difference between the elution end time and the elution start time of the elution stage;

[0018] The test products include one or more of pravastatin, pravastatin salts and pravastatin-related substances.

[0019] In the mobile phase A, the volume ratio of water, phosphate buffer and acetonitrile can be (50-54):(28-32):(16-20), preferably 52:30:18.

[0020] In the mobile phase B, the volume ratio of water, phosphate buffer and acetonitrile can be (8-12):(28-32):(58-62), preferably 10:30:60.

[0021] In the mobile phases A and B, the pH value of the phosphate buffer is 7.0.

[0022] The elution time of the first elution stage is preferably 3 minutes.

[0023] The elution time of the second elution stage is preferably 27 minutes.

[0024] The elution time of the third elution stage is preferably 5 minutes.

[0025] The elution time of the fourth elution stage is preferably 1 min.

[0026] The elution time of the fifth elution stage is preferably 4 minutes.

[0027] In the first elution stage, the volume ratio of mobile phase A is preferably maintained at 100%, and the volume ratio of mobile phase B is preferably maintained at 0%.

[0028] In the second elution stage, the volume ratio of mobile phase A is preferably decreased from 100% to 0%, and the volume ratio of mobile phase B is preferably increased from 0% to 100%.

[0029] In the third elution stage, the volume ratio of mobile phase A is preferably maintained at 0%, and the volume ratio of mobile phase B is preferably maintained at 100%.

[0030] In the fourth elution stage, the volume ratio of mobile phase A is preferably increased from 0% to 100%, and the volume ratio of mobile phase B is preferably decreased from 100% to 0%.

[0031] In the fifth elution stage, the volume ratio of mobile phase A is preferably maintained at 100%, and the volume ratio of mobile phase B is preferably maintained at 0%.

[0032] The five-stage gradient elution of the high performance liquid chromatography is preferably:

[0033] Elution stage Elution time / min Mobile phase A (%) Mobile phase B (%) First elution stage 3 100％→100％ 0％→0％ Second elution stage 27 100％→0％ 0％→100％ The third elution stage 5 100％→0％ 0％→0％ Fourth elution stage 1 0％→100％ 100％→0％ Fifth elution stage 4 100％→100％ 0％→0％ .

[0034] The column temperature of the liquid chromatography method may be 25-35°C, preferably 28°C or 30°C, more preferably 28°C.

[0035] The detection wavelength of the high performance liquid chromatography method may be 236-240 nm and 218-222 nm, preferably 236 nm and 220 nm.

[0036] The detector of the high performance liquid chromatography method may be an ultraviolet visible light (UV / Vis) detector or a photodiode array (PDA) detector; the ultraviolet visible light (UV / Vis) detector is preferably a 2489 ultraviolet visible light (UV / Vis) detector (e.g., a Waters 2489 ultraviolet visible light (UV / Vis) detector); the photodiode array (PDA) detector is preferably a 2998 photodiode array (PDA) detector (e.g., a Waters 2998 photodiode array (PDA) detector).

[0037] The detector of the HPLC method is more preferably a photodiode array (PDA) detector (eg Waters 2998 photodiode array (PDA) detector).

[0038] The particle size of the filler of the chromatographic column may be 3.0-5.0 μm, preferably 3.5 μm.

[0039] The inner diameter of the chromatographic column may be 4.0-5.0 mm, preferably 4.6 mm.

[0040] The length of the chromatographic column may be 75-150 mm, preferably 150 mm.

[0041] The chromatography column is preferably XBridge Shield RP18 (eg Waters XBridge Shield RP18).

[0042] The test product is preferably pravastatin bulk drug and / or pravastatin preparation.

[0043] The pravastatin related substances may include one or more of the following compounds:

[0044]

[0045] The injection volume of the high performance liquid chromatography method can be 8-12 μL, preferably 10 μL.

[0046] The flow rate of the HPLC method may be 0.8-1.2 mL / min, preferably 1.0 mL / min.

[0047] The injector temperature of the HPLC method may be 8-12°C, preferably 10°C.

[0048] The sample to be tested can be dissolved in a solvent before injection.

[0049] The solvent may be a mixture of methanol and water, or a mixture of water, phosphate buffer and acetonitrile.

[0050] In the solvent, the volume ratio of water, phosphate buffer and acetonitrile can be (50-54):(28-32):(16-20), preferably 52:30:18.

[0051] In the solvent, the pH of the phosphate buffer may be 6.8-7.2, preferably 7.0.

[0052] The molar volume ratio of the test product to the solvent may be 0.8-1.2 mg / L, for example 1.0 mg / L. In a preferred embodiment,

[0053] The test product includes components of group (1) or group (2):

[0054] Group (1) pravastatin,

[0055] Group (2) pravastatin,

[0056] The chromatographic column is XBridge Shield RP18 (e.g. Waters XBridge Shield RP18); the column temperature of the liquid chromatography is 28°C;

[0057] In the mobile phase A, the volume ratio of water, phosphate buffer and acetonitrile is 52:30:18;

[0058] In the mobile phase B, the volume ratio of water, phosphate buffer and acetonitrile is 10:30:60;

[0059] The five-stage gradient elution is:

[0060] Elution stage Elution time / min Mobile phase A (%) Mobile phase B (%) First elution stage 3 100％→100％ 0％→0％ Second elution stage 27 100％→0％ 0％→100％ The third elution stage 5 100％→0％ 0％→0％ Fourth elution stage 1 0％→100％ 100％→0％ Fifth elution stage 4 100％→100％ 0％→0％ ;

[0061] The detector of the high performance liquid chromatography is a 2489 ultraviolet visible light (UV / Vis) detector (eg, Waters 2489 ultraviolet visible light (UV / Vis) detector).

[0062] In a preferred embodiment,

[0063] The test products are pravastatin,

[0064] The chromatographic column is XBridge Shield RP18 (e.g. Waters XBridge Shield RP18);

[0065] The column temperature of the liquid chromatography method is 25°C;

[0066] In the mobile phase A, the volume ratio of water, phosphate buffer and acetonitrile is 52:30:18;

[0067] In the mobile phase B, the volume ratio of water, phosphate buffer and acetonitrile is 10:30:60;

[0068] The five-stage gradient elution is:

[0069] Elution stage Elution time / min Mobile phase A (%) Mobile phase B (%) First elution stage 3 100％→100％ 0％→0％ Second elution stage 27 100％→0％ 0％→100％ The third elution stage 5 100％→0％ 0％→0％ Fourth elution stage 1 0％→100％ 100％→0％ Fifth elution stage 4 100％→100％ 0％→0％ ;

[0070] The detector of the high performance liquid chromatography method is a 2998 photodiode array (PDA) detector (eg, a Waters 2998 photodiode array (PDA) detector).

[0071] Without violating the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0072] The reagents and raw materials used in the present invention are commercially available.

[0073] The positive and progressive effects of the present invention are: the detection method can simultaneously achieve effective separation of pravastatin and its adjacent unknown degradation impurities, and impurity D and its adjacent unknown impurities, and can achieve accurate detection of pravastatin and impurity D, is easy to operate and control, and has accurate detection results; further, it can also achieve improved separation of impurity B and impurity E, thereby improving the accuracy of the contents of pravastatin, impurity D, impurity B and impurity E; further, the detection method has also passed methodological verification, providing an effective detection method for the content of pravastatin-related substances. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] Figure 1 is the HPLC spectrum of the sample 1 to be tested in Example 1;

[0075] Figure 2 It is the HPLC spectrum of the sample 1 to be tested in Comparative Example 1;

[0076] Figure 3 This is the HPLC spectrum of sample 3 to be tested in Example 3. DETAILED DESCRIPTION

[0077] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0078] Example 1

[0079] Test sample 1: The raw material drug (Shanghai Tianwei Biopharmaceutical Co., Ltd.) was treated with acid (1 mL of 0.5 mol / L hydrochloric acid solution, 20 minutes), and dissolved with water-phosphate buffer (pH 7.0)-acetonitrile (52:30:18) to obtain test sample 1; the specific components were pravastatin, impurity A, impurity B, impurity D and various unknown impurities.

[0080] Test sample 2: Pravastatin sodium, impurity A, impurity B, impurity C, impurity D, impurity E, impurity F, impurity G, impurity H and impurity I were mixed and dissolved with water-phosphate buffer (pH 7.0)-acetonitrile (52:30:18), wherein pravastatin sodium was 1 mg / mL and the other impurities were all 2 μg / mL, to obtain test sample 2.

[0081] Test sample 3: Pravastatin sodium, impurity A, impurity B, impurity C, impurity D, impurity E, impurity F, impurity G, impurity H and impurity I were mixed and dissolved with water-phosphate buffer (pH 7.0)-acetonitrile (52:30:18), wherein pravastatin sodium and other impurities were both 2 μg / mL, to obtain test sample 3, i.e., the positioning solution of each component.

[0082] Using a Waters XBridge Shield RP18 chromatographic column (4.6 mm × 150 mm, 3.5 μm), the sample 1 to be tested was injected under the chromatographic conditions shown in Table 2. The results showed that the main component Pravastatin and the adjacent unknown degradation impurities could be basically completely separated, as shown in FIG. Figure 1 As shown, the peak value, peak width / half peak width, separation degree and other data of the measured impurities are shown in Table 3 below.

[0083] Phosphate buffer: Weigh about 9.2 g of phosphoric acid, dilute to 1000 mL with water, and adjust the pH to 7.0 with triethylamine.

[0084] Detector model: Waters 2489 UV / Vis detector.

[0085] Table 2. Chromatographic conditions

[0086]

[0087] Table 3. Spectral data of API using Waters XBridge Shield RP18

[0088]

[0089]

[0090] From the above results, it can be seen that using the Waters XBridge Shield RP18 column, pravastatin and its adjacent unknown degradation impurities, as well as impurity D and its adjacent unknown impurities can be completely separated.

[0091] Example 2

[0092] Optimization of column temperature and chromatographic gradient

[0093] The samples 1 and 2 to be tested were tested using a Waters XBridge Shield RP18 chromatographic column at different temperatures and under the chromatographic gradients shown in Table 4. Other conditions were consistent with those in Example 1. The results are shown in Table 5.

[0094] Detector model: Waters 2489 UV / Vis detector.

[0095] Table 4. Chromatographic gradient

[0096] Time (minutes) Mobile phase A (%) Mobile phase B (%) 0 100 0 3 100 0 30 0 100 35 0 100 36 100 0 40 100 0

[0097] Table 5. Test results of separation of pravastatin related substances at different column temperatures

[0098]

[0099]

[0100] The column temperature and chromatographic gradient were adjusted to ensure that all known impurities in the mixed solution and pravastatin could be completely separated, and that unknown degradation impurities that might exist in the raw material drug could also be completely separated from the known impurities.

[0101] From the above results, it can be seen that the higher the column temperature, the better the separation between impurity B and impurity E, the better the separation between the main peak and its adjacent unknown degradation impurities, but the worse the separation between the main peak and impurity A, and between impurity D and adjacent unknown impurities. When the column temperature is 28°C, the separation between impurities is greater than 1.5, and the separation between the main component and the adjacent impurities is greater than 2.0. Therefore, in the detection method of pravastatin related substances, the optimal column temperature is 28°C.

[0102] Example 3

[0103] Optimization of chromatographic gradients and detectors

[0104] Sample 3 to be tested was injected, and the chromatographic gradient was as shown in Table 4. The detector used was Waters 2998 photodiode array (PDA) detector. Other test conditions were consistent with those in Example 1. The spectrum was measured as follows: Figure 3 As shown, the relevant data of the spectrum are shown in Table 6. Under this gradient, the separation degree between impurity B and impurity E is 1.81.

[0105] Table 4. Chromatographic gradient

[0106]

[0107]

[0108] Table 6. Measured results of each component positioning solution Figure 3 Corresponding atlas data

[0109] Peak name Retention time (min) Peak area Peak width(sec) Separation Impurity F 2.423 4,9667 14.5 / Impurity B 5.898 4,4409 21.5 21.05 Impurity E 6.277 4,3654 21.5 1.81 Impurity G 9.358 3,2986 16 16.98 Impurity A 10.503 5,1411 16.5 7.6 Pravastatin 10.983 4,6825 15 3.31 Impurity H 12.225 4,1585 15.5 8.62 Impurity C 12.878 4,7260 17 4.46 Impurity D 18.144 4,9558 17.5 33.38 Impurity I 28.663 5,6178 21.5 55.07

[0110] Note: Resolution refers to the separation between the peak and the previous peak.

[0111] Example 4

[0112] Optimizing the detection of impurities

[0113] Pharmacopoeias of all countries select 238nm as the detection wavelength. The wavelength durability test was conducted within the range of 238nm±2nm, the chromatographic column was Agilent Zorbax SB-C18 (4.6×75μm, 3.5μm), the solvent was mobile phase A, and other conditions were consistent with the chromatographic conditions of Example 1. The results showed that the RSD of the results of impurity G and impurity H were greater than 10%, see Table 7:

[0114] Table 7. Wavelength durability test results

[0115]

[0116]

[0117] The stock solutions of each impurity reference substance and the stock solution of pravastatin reference substance were respectively injected into the liquid chromatograph, and full wavelength scanning was performed using a PDA detector. The results are shown in Table 8.

[0118] Table 8. Maximum absorption wavelength of each component

[0119]

[0120] As can be seen from the above table, the maximum absorption wavelength of impurity G is 219.3nm, and the maximum absorption wavelength of impurity H is 233.4nm, which are inconsistent with the main component (maximum absorption wavelength 236.9nm), resulting in large differences in the measurement results of the two impurities within the range of 238nm±2nm. Therefore, the detection wavelength of impurity G is set to 220nm, and the detection wavelength of other impurities is set to 236nm. It has been verified that the selected wavelength has good durability in the range of ±2nm, and the RSD of the measurement results of each impurity is no more than 10%, indicating that the measurement results of each impurity are not affected by the wavelength deviation. The results are shown in Table 9:

[0121] Table 9. Wavelength durability test results

[0122]

[0123]

[0124] The optimal detection wavelength of the detection method for pravastatin-related substances is 236nm+220nm.

[0125] Based on the above optimization conditions, the optimized measurement method is shown in Table 10.

[0126] Table 10. Optimal detection methods for pravastatin related substances

[0127]

[0128] The method has passed the methodology validation, including specificity, linearity, limit of quantification, limit of detection, accuracy, repeatability, solution stability and durability. The method will be more applicable to sample detection and more durable.

[0129] Comparative Example 1

[0130] The chromatographic column recommended by ChP 2020 is Aglient Zorbax SB-C18 column (4.6 mm × 75 mm, 3.5 μm). The sample 1 to be tested was injected under the chromatographic conditions shown in Table 5. The results showed that the main component Pravastatin and its adjacent unknown degradation impurities could not be separated, and impurity A and its adjacent unknown impurities, and impurity D and its adjacent unknown impurities could not be effectively separated. Figure 2 The spectrum data are shown in Table 6 below.

[0131] Phosphate buffer: Weigh about 9.2 g of phosphoric acid, dilute to 1000 mL with water, and adjust the pH to 7.0 with triethylamine.

[0132] Detector model: Waters 2489 UV / Vis detector.

[0133] Table 11. Chromatographic conditions recommended by ChP 2020

[0134]

[0135]

[0136] Table 12. Spectral data of API using Aglient Zorbax SB-C18

[0137]

[0138] Note: “-” indicates that pravastatin and the adjacent unknown degradation impurity peak of pravastatin overlap and cannot be completely separated, making it difficult to calculate the resolution.

Claims

1. A method for detecting pravastatin related substances, characterized in that: The method comprises the following steps: using high performance liquid chromatography to detect the sample to be tested, wherein the filler of the chromatographic column of the liquid chromatography is ethylene bridge hybrid particles; The mobile phase of the high performance liquid chromatography is composed of mobile phase A and mobile phase B; The mobile phases A and B are a mixture of water, phosphate buffer and acetonitrile; In the mobile phases A and B, the pH value of the phosphate buffer is 6.8-7.2; The high performance liquid chromatography method adopts a five-stage gradient elution: The test products include one or more of pravastatin, pravastatin salts and pravastatin-related substances.

2. The detection method according to claim 1, characterized in that In the mobile phase A, the volume ratio of water, phosphate buffer and acetonitrile is (50-54):(28-32):(16-20); In the mobile phase B, the volume ratio of water, phosphate buffer and acetonitrile is (8-12): (28-32): (58-62) And / or, in the mobile phases A and B, the pH value of the phosphate buffer is 7.

0.

3. The detection method according to claim 2, characterized in that In the mobile phase A, the volume ratio of water, phosphate buffer and acetonitrile is 52:30:18; In the mobile phase B, the volume ratio of water, phosphate buffer and acetonitrile is 10:30:

60.

4. The detection method according to claim 1, characterized in that The five-stage gradient elution satisfies one or more of the following conditions: ① The elution time of the first elution stage is 3 minutes; ② The elution time of the second elution stage is 27 minutes; ③ The elution time of the third elution stage is 5 minutes; ④ The elution time of the fourth elution stage is 1 min; ⑤ The elution time of the fifth elution stage is 4 minutes; ⑥ In the first elution stage, the volume ratio of mobile phase A is maintained at 100%, and the volume ratio of mobile phase B is maintained at 0%; ⑦ In the second elution stage, the volume ratio of mobile phase A is decreased from 100% to 0%, and the volume ratio of mobile phase B is increased from 0% to 100%; ⑧ In the third elution stage, the volume ratio of mobile phase A is maintained at 0%, and the volume ratio of mobile phase B is maintained at 100%; ⑨ In the fourth elution stage, the volume ratio of mobile phase A increases from 0% to 100%, and the volume ratio of mobile phase B decreases from 100% to 0%; ⑩ In the fifth elution stage, the volume ratio of mobile phase A is maintained at 100%, and the volume ratio of mobile phase B is maintained at 0%.

5. The detection method according to claim 4, characterized in that: The five-stage gradient elution of the high performance liquid chromatography is:

6. The detection method according to claim 1, characterized in that The detection method meets one or more of the following conditions: ① The column temperature of the liquid chromatography is 25-35°C; ② The detection wavelengths of the high performance liquid chromatography are 236-240nm and 218-222nm; ③ The detector of the high performance liquid chromatography is an ultraviolet visible light detector or a photodiode array detector; ④ The particle size of the filler of the chromatographic column is 3.0-5.0 μm; ⑤ The inner diameter of the chromatographic column is 4.0-5.0 mm; ⑥The length of the chromatographic column is 75-150mm; ⑦The chromatographic column is XBridge Shield RP18; ⑧ The test product is pravastatin bulk drug and / or pravastatin preparation; ⑨ The pravastatin related substances include one or more of the following compounds, ⑩ The sample to be tested is dissolved in a solvent before injection; The injection volume of the HPLC method is 8-12 μL; The flow rate of the HPLC method is 0.8-1.2 mL / min; The injector temperature of the HPLC method is 8-12°C.

7. The detection method according to claim 6, characterized in that The detection method meets one or more of the following conditions: ① The column temperature of the liquid chromatography is 28°C or 30°C; ② The detection wavelength of the high performance liquid chromatography is 236nm and 220nm; ③ The detector of the high performance liquid chromatography is a photodiode array detector; ④ The particle size of the filler of the chromatographic column is 3.5 μm; ⑤ The inner diameter of the chromatographic column is 4.6 mm; ⑥The length of the chromatographic column is 150 mm; ⑦ The injection volume of the high performance liquid chromatography method is 10 μL; ⑧ The flow rate of the high performance liquid chromatography is 1.0 mL / min; ⑨ The injector temperature of the HPLC method is 10°C; ⑩ The solvent is a mixture of methanol and water, or a mixture of water, phosphate buffer and acetonitrile.

8. The detection method according to claim 7, characterized in that The detection method meets one or more of the following conditions: ① The column temperature of the liquid chromatography is 28°C; ② The ultraviolet visible light detector is a 2489 ultraviolet visible light detector; the photodiode array detector is a 2998 photodiode array detector; ③ In the solvent, the volume ratio of water, phosphate buffer and acetonitrile is (50-54):(28-32):(16-20); ④ In the solvent, the pH of the phosphate buffer is 6.8-7.2; ⑤ The molar volume ratio of the test product to the solvent is 0.8-1.2 mg / L.

9. The detection method according to claim 8, characterized in that: The detection method meets one or both of the following conditions: ① In the solvent, the volume ratio of water, phosphate buffer and acetonitrile is 52:30:18; ② In the solvent, the pH of the phosphate buffer is 7.0; ③ The molar volume ratio of the test product to the solvent is 1.0 mg / L.

10. The detection method according to claim 1, characterized in that: The detection method is the following scheme ① or ②: Solution ①: The test product includes components of group (1) or group (2): Group (1) pravastatin, Group (2) pravastatin, The chromatographic column is XBridge Shield RP18; The column temperature of the liquid chromatography method is 28°C; In the mobile phase A, the volume ratio of water, phosphate buffer and acetonitrile is 52:30:18; In the mobile phase B, the volume ratio of water, phosphate buffer and acetonitrile is 10:30:60; The five-stage gradient elution is: ； The detector of the high performance liquid chromatography is a 2489 ultraviolet visible light detector; Scheme ②: The products to be tested include: Pravastatin, The chromatographic column is XBridge Shield RP18; The column temperature of the liquid chromatography method is 25°C; In the mobile phase A, the volume ratio of water, phosphate buffer and acetonitrile is 52:30:18; In the mobile phase B, the volume ratio of water, phosphate buffer and acetonitrile is 10:30:60; The five-stage gradient elution is: ； The detector of the high performance liquid chromatography is a 2998 photodiode array detector.

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