Process for preparing imipenem impurity B

Abstract

The application belongs to the technical field of medicine, and particularly relates to a preparation method of imipenem impurity B, which comprises the following steps: 1) imipenem is added into water to obtain an imipenem suspension, concentrated sulfuric acid is added drop by drop and continuously stirred, after the solution is clarified, an alkaline solution is used to adjust the pH to neutral, and water is added to dilute to obtain an imipenem impurity B crude product solution; 2) the imipenem impurity B crude product solution is injected into a dynamic axial compression column system, gradient elution is carried out, and target component effluent is collected; 3) the target component effluent is freeze-dried to obtain imipenem impurity B pure product; the process (1) has short reaction time and high yield, concentrated sulfuric acid is added drop by drop into the imipenem solution until the solution is clarified, the reaction is completed, the degradation time is shortened, and the content of other impurities is reduced; (2) the preparation efficiency is high, the preparation process can realize continuous sampling, the preparation time is short, and the efficiency is high; (3) the purity is high, and the HPLC purity of the prepared imipenem impurity B can be as high as 97.6%.

Description

Technical Field

[0001] This invention belongs to the field of pharmaceutical synthesis, specifically relating to a method for preparing imipenem impurity B. Background Technology

[0002] Imipenem belongs to the carbapenem class of antibiotics and has antibacterial activity against Gram-positive and Gram-negative aerobic and anaerobic bacteria. Due to its β-lactam structure and numerous active groups, it is highly susceptible to impurities arising during preparation, storage, and use through oxidation and hydrolysis. The European Pharmacopoeia 9.0 lists two imipenem impurities: impurity A with a relative retention time of 0.8, and a pair of diastereomers, impurity B, with a relative retention time of 0.35. Investigations have revealed that impurity B exists in two structural forms; the two isomers interconvert and are structurally unstable, making it difficult to obtain a high-purity solid. Therefore, no impurity reference standard is available for sale. The structures of the two isomers of impurity B are shown in Formulas I-1 and I-2:

[0003]

[0004] Pascale Taibi et al. reported that 0.5 mg of imipenem was degraded with 1.0 mL of 0.05 M sulfuric acid for 1 h, neutralized to 7.0 with barium hydroxide, the precipitate was filtered off, and the solution was passed through a 25*1.0 cm C18 reversed-phase column to obtain impurity B with two isomers in a 1:1 ratio. This method has a long degradation time, uses a small preparative column, requires a long enrichment period for lattice-bound products, makes it difficult to ensure the stability of impurity B in solution, and results in a low concentration of imipenem impurity B in the acid hydrolysis solution, increasing the difficulty of subsequent preparation. Summary of the Invention

[0005] To address the above problems and obtain a high-purity solid impurity B to meet the requirements for structural identification and as a working control, this invention provides a method for preparing imipenem impurity B.

[0006] A method for preparing imipenem impurity B includes the following steps:

[0007] 1) Imipenem was added to water to obtain an imipenem suspension. Concentrated sulfuric acid was added dropwise while stirring continuously. After the solution became clear, the pH was adjusted to neutral with an alkaline solution and diluted with water to obtain a crude solution of imipenem impurity B.

[0008] 2) Inject the crude imipenem impurity B solution into a dynamic axial compression column system, perform gradient elution, and collect the eluent of the target component;

[0009] 3) Freeze-dry the eluent of the target component to obtain pure imipenem impurity B;

[0010]

[0011] Preferably, in step 1), the mass-to-volume ratio of imipenem to water in the imipenem suspension is 1:40-60, where mass is expressed in g and volume in mL.

[0012] More preferably, the mass-to-volume ratio of imipenem to concentrated sulfuric acid in step 1) is 1:0.8 to 1.2, wherein the mass is in g and the volume is in mL.

[0013] Preferably, the alkaline solution in step 1) is selected from sodium hydroxide solution and potassium hydroxide solution.

[0014] Preferably, the concentration of the alkaline solution in step 1) is 0.5–5 mol / L.

[0015] Preferably, in step 2), the mobile phase A of the gradient elution is purified water and the mobile phase B is acetonitrile.

[0016] Preferably, the chromatographic column used for gradient elution in step 2) is a Hanbang DAC-50 dynamic axial compression column system, and the preparation column is made of 316L stainless steel.

[0017] Preferably, the chromatographic column used for gradient elution in step 2) contains Sepax HP C18 10μm packing material.

[0018] Preferably, the column temperature of the gradient elution column in step 2) is room temperature.

[0019] Preferably, the gradient elution detection wavelength in step 2) is 210 nm.

[0020] Preferably, the gradient elution flow rate in step 2) is 50 mL / min.

[0021] Preferably, the gradient elution in step 2) is performed according to the following gradient elution program: initial elution separation and subsequent elution equilibration. The initial elution separation program is as follows: at 0 minutes, the volume ratio of mobile phase B is 0%–2%; at 7 minutes, the volume ratio of mobile phase B increases to 2%–4%; from 7.1 to 17 minutes, the volume ratio of mobile phase B increases from 10%–15% to 20%–25%; from 17.1 to 22 minutes, the volume ratio of mobile phase B is maintained at 50%–55%; after the initial elution separation is completed, from 22.1 to 27 minutes, the volume ratio of mobile phase B is maintained at 0%–2% for subsequent elution equilibration, and then the sample is injected again. The initial elution separation and subsequent elution equilibration are cycled sequentially.

[0022] Preferably, the gradient elution in step 2) is performed according to the following gradient elution program: initial elution separation and subsequent elution equilibration. The initial elution separation program is as follows: at 0 minutes, the volume ratio of mobile phase B is 3%–4%; at 7 minutes, the volume ratio of mobile phase B increases to 5%–6%; from 7.1 to 17 minutes, the volume ratio of mobile phase B increases from 10%–15% to 20%–25%; from 17.1 to 22 minutes, the volume ratio of mobile phase B is maintained at 50%–55%; after the initial elution separation is completed, from 22.1 to 27 minutes, the volume ratio of mobile phase B is maintained at 3%–4% for subsequent elution equilibration, and then the sample is injected again. The initial elution separation and subsequent elution equilibration are cycled sequentially.

[0023] More preferably, the gradient elution in step 2) is performed according to the following gradient elution program: initial elution separation and subsequent elution equilibration. The initial elution separation program is as follows: at 0 minutes, the volume ratio of mobile phase B is 3%; at 7 minutes, the volume ratio of mobile phase B increases to 5%; from 7.1 to 17 minutes, the volume ratio of mobile phase B increases from 10% to 20%; from 17.1 to 22 minutes, the volume ratio of mobile phase B is maintained at 50%; after the initial elution separation is completed, from 22.1 to 27 minutes, the volume ratio of mobile phase B is maintained at 3% for subsequent elution equilibration, and then the sample is injected again. The initial elution separation and subsequent elution equilibration are cycled sequentially.

[0024] Preferably, the freeze-drying curve in step 3) is as follows:

[0025]

[0026] More preferably, the freeze-drying curve in step 3) is as follows:

[0027]

[0028] The present invention achieves the following beneficial effects compared to the prior art:

[0029] (1) The reaction time is short and the yield is high. In this invention, concentrated sulfuric acid is added dropwise to imipenem solution until the solution is clear, and the reaction is completed. This shortens the degradation time and reduces the content of other impurities.

[0030] (2) High preparation efficiency: The preparation process of this invention can achieve continuous sample injection, and the preparation time is short and the efficiency is high.

[0031] (3) High purity: The HPLC purity of imipenem impurity B prepared by this invention can reach up to 97.6%. Attached Figure Description

[0032] Figure 1 HPLC chromatogram of crude imipenem impurity B solution in Example 1;

[0033] Figure 2 The online preparation chromatogram of crude imipenem impurity B solution in Example 1;

[0034] Figure 3 HPLC chromatogram of pure imipenem impurity B in Example 1;

[0035] Figure 4 The online preparation chromatogram of the crude imipenem impurity B solution in Example 8;

[0036] Figure 5 HPLC chromatogram of crude imipenem impurity B solution in Comparative Example 1;

[0037] Figure 6 Online preparation chromatogram of crude imipenem impurity B solution in Comparative Example 2;

[0038] Figure 7 HPLC chromatogram of pure imipenem impurity B in Comparative Example 2; Detailed Implementation

[0039] The beneficial effects of the present invention will be further described through the following embodiments. These embodiments are for illustrative purposes only and do not limit the scope of the present invention. At the same time, obvious changes and modifications made by those skilled in the art according to the present invention are also included within the scope of the present invention.

[0040] Reference Example:

[0041] The HPLC conditions for purity determination of imipenem impurity B are as follows:

[0042] Column: YMC-Triart C 18 4.6×150mm, 3μm

[0043] Detection wavelength: 210nm

[0044] Flow rate: 1.0 ml / min

[0045] Column temperature: 30℃

[0046] Mobile phase A: 2.6mM sodium dihydrogen phosphate-7.3mM disodium hydrogen phosphate buffer (pH adjusted to 7.30 with phosphate):acetonitrile = 993:7

[0047] Mobile phase B: 2.6mM sodium dihydrogen phosphate-7.3mM disodium hydrogen phosphate buffer (pH adjusted to 7.30 with phosphate):acetonitrile = 750:250

[0048] The gradient elution for HLPC analysis is as follows:

[0049]

[0050] The pair of target peaks with retention times of 2.2 min and 2.3 min correspond to two isomers of imipenem impurity B.

[0051] The crude imipenem used in the embodiments of this invention has a purity of over 90%.

[0052] Example 1

[0053] 1) Add 1g of crude imipenem to 50mL of purified water to obtain an imipenem suspension. Add 1mL of concentrated sulfuric acid dropwise while stirring continuously. Once the sample solution becomes clear, immediately add 1M sodium hydroxide solution to adjust the pH to 7.0, and dilute with water to 100mL. HPLC analysis of the diluted solution showed that the purities of the two epimers of imipenem impurity B were 29.7% and 38.3%, respectively, totaling 68.0%. See the attached HPLC chromatogram for the results. Figure 1 The two peaks labeled 1 / 2 correspond to the two isomers of imipenem impurity B.

[0054] 2) Inject the crude imipenem impurity B solution into a dynamic axial compression column system, perform gradient elution, and collect the eluent of the target component;

[0055] The preparation and purification method is as follows:

[0056] Column: Hanbang DAC-50 dynamic axial compression column system, preparative column material is 316L stainless steel.

[0057] Packing material: Sepax HP C18 10μm

[0058] Column temperature: room temperature

[0059] Detection wavelength: 210nm

[0060] Flow rate: 50 mL / min

[0061] Mobile phase A: purified water

[0062] Mobile phase B: Acetonitrile

[0063] Single injection volume: 20 mL

[0064] Elution was performed using the following gradient elution program: initial elution separation and subsequent elution equilibration. The initial elution separation program was as follows: at 0 minutes, the volume ratio of mobile phase B was 3%; at 7 minutes, the volume ratio of mobile phase B increased to 5%; from 7 to 7.1 minutes, the volume ratio of mobile phase B increased from 5% to 10%; from 7.1 to 17 minutes, the volume ratio of mobile phase B increased from 10% to 20%; and from 17.1 to 22 minutes, the volume ratio of mobile phase B was maintained at 50%. After the initial elution separation, from 22.1 to 27 minutes, the volume ratio of mobile phase B was maintained at 3% for subsequent elution equilibration. The process was repeated, involving initial elution separation and subsequent elution equilibration, for a total of 5 injections. The target component with a retention time of approximately 9.4 minutes was collected, and the prepared chromatogram is shown in the appendix. Figure 2 .

[0065] 3) The collected solution was directly freeze-dried at low temperature, and the freeze-drying curve was as follows:

[0066]

[0067]

[0068] After lyophilization, the sample was weighed and analyzed. The concentration of imipenem impurity B was 566 mg, the HPLC purity was 97.6%, and the yield was 56.6%. The analytical chromatogram is attached. Figure 3 The two peaks labeled 1 / 2 correspond to the two isomers of imipenem impurity B.

[0069] Example 2

[0070] 1) The preparation of the crude imipenem impurity B solution was the same as in Example 1;

[0071] 2) Inject the crude imipenem impurity B solution into a dynamic axial compression column system, perform gradient elution, and collect the eluent of the target component;

[0072] Other conditions are the same as in Example 1.

[0073] Elution was performed using the following gradient elution program: initial elution separation and subsequent elution equilibration. The initial elution separation program was as follows: at 0 minutes, the volume ratio of mobile phase B was 4%; at 7 minutes, the volume ratio of mobile phase B increased to 6%; from 7.1 to 17 minutes, the volume ratio of mobile phase B increased from 10% to 20%; and from 17.1 to 22 minutes, the volume ratio of mobile phase B was maintained at 55%. After the initial elution separation, from 22.1 to 27 minutes, the volume ratio of mobile phase B was maintained at 4% for subsequent elution equilibration. Then, the sample was injected again, and the cycle of initial elution separation and subsequent elution equilibration was repeated for a total of 5 injections. The target component with a retention time of approximately 7.7 minutes was collected.

[0074] 3) The collected solution was directly freeze-dried at low temperature. Freeze-drying curve:

[0075]

[0076] After lyophilization, the sample was weighed and analyzed. The impurity B of imipenem was 535 mg, the HPLC purity was 97.2%, and the yield was 53.5%.

[0077] Example 3

[0078] 1) The preparation of the crude imipenem impurity B solution was the same as in Example 1;

[0079] 2) Inject the crude imipenem impurity B solution into a dynamic axial compression column system, perform gradient elution, and collect the eluent of the target component;

[0080] Other conditions are the same as in Example 1.

[0081] Elution was performed using the following gradient elution program: initial elution separation and subsequent elution equilibration. The initial elution separation program was as follows: at 0 minutes, the volume ratio of mobile phase B was 2%; at 7 minutes, the volume ratio of mobile phase B increased to 4%; from 7.1 to 17 minutes, the volume ratio of mobile phase B increased from 15% to 25%; and from 17.1 to 22 minutes, the volume ratio of mobile phase B was maintained at 55%. After the initial elution separation, from 22.1 to 27 minutes, the volume ratio of mobile phase B was maintained at 2% for subsequent elution equilibration. Then, the sample was injected again, and the cycle of initial elution separation and subsequent elution equilibration was repeated for a total of 5 injections. The target component with a retention time of approximately 10.9 minutes was collected.

[0082] 3) The collected solution was directly freeze-dried at low temperature. Freeze-drying curve:

[0083]

[0084] After lyophilization, the sample was weighed and analyzed. The impurity B of imipenem was 529 mg, the yield was 52.9%, and the HPLC purity was 97.0%.

[0085] Example 4

[0086] 1) The preparation of the crude imipenem impurity B solution was the same as in Example 1;

[0087] 2) Inject the crude imipenem impurity B solution into a dynamic axial compression column system, perform gradient elution, and collect the eluent of the target component;

[0088] Other conditions are the same as in Example 1.

[0089] Elution was performed using the following gradient elution program: initial elution separation and subsequent elution equilibration. The initial elution separation program was as follows: at 0 minutes, the volume ratio of mobile phase B was 0%; at 7 minutes, the volume ratio of mobile phase B increased to 3%; from 7.1 to 17 minutes, the volume ratio of mobile phase B increased from 10% to 20%; and from 17.1 to 22 minutes, the volume ratio of mobile phase B was maintained at 55%. After the initial elution separation, from 22.1 to 27 minutes, the volume ratio of mobile phase B was 0 for subsequent elution equilibration. The sample was then injected again, and the cycle of initial elution separation and subsequent elution equilibration was repeated for a total of 5 injections. The target component with a retention time of approximately 12.5 minutes was collected.

[0090] 3) The collected solution was directly freeze-dried at low temperature. Freeze-drying curve:

[0091]

[0092] After lyophilization, the sample was weighed and analyzed. The impurity B of imipenem was 521 mg, the HPLC purity was 97.3%, and the yield was 52.1%.

[0093] Example 5

[0094] 1) The preparation of the crude imipenem impurity B solution was the same as in Example 1;

[0095] 2) Inject the crude imipenem impurity B solution into a dynamic axial compression column system, perform gradient elution, and collect the eluent of the target component;

[0096] Other conditions are the same as in Example 1.

[0097] Elution was performed using the following gradient elution program: initial elution separation and subsequent elution equilibration. The initial elution separation program was as follows: at 0 minutes, the volume ratio of mobile phase B was 0%; at 7 minutes, the volume ratio of mobile phase B increased to 2%; from 7.1 to 17 minutes, the volume ratio of mobile phase B increased from 10% to 23%; and from 17.1 to 22 minutes, the volume ratio of mobile phase B was maintained at 50%. After initial elution separation, from 22.1 to 27 minutes, the volume ratio of mobile phase B was 0% for subsequent elution equilibration. The sample was then injected again, and the cycle of initial elution separation and subsequent elution equilibration was repeated for a total of 5 injections. The target component with a retention time of approximately 12.8 minutes was collected.

[0098] 3) The collected solution was directly freeze-dried at low temperature. Freeze-drying curve:

[0099]

[0100]

[0101] After lyophilization, the sample was weighed and analyzed. The impurity B of imipenem was 517 mg, the HPLC purity was 96.1%, and the yield was 51.7%.

[0102] Example 6

[0103] 1) Add 1g of crude imipenem to 40mL of purified water to obtain an imipenem suspension. Add 0.8mL of concentrated sulfuric acid dropwise while stirring continuously. Once the sample solution becomes clear, immediately add 0.5M potassium hydroxide solution to adjust the pH to 7.0, and dilute with water to 100mL. HPLC analysis of the diluted solution showed that the purities of the two epimers of imipenem impurity B were 28.0% and 35.9%, respectively, totaling 63.9%.

[0104] 2) Inject the crude imipenem impurity B solution into a dynamic axial compression column system, perform gradient elution, and collect the target component eluent; the elution conditions and elution gradient are the same as in Example 1.

[0105] 3) The collected solution was directly freeze-dried at low temperature. Freeze-drying curve:

[0106]

[0107] After lyophilization, the sample was weighed and analyzed. The impurity B of imipenem was 527 mg, the HPLC purity was 97.1%, and the yield was 52.7%.

[0108] Example 7

[0109] 1) Add 1g of crude imipenem to 60mL of purified water to obtain an imipenem suspension. Add 1.2mL of concentrated sulfuric acid dropwise while stirring continuously. Once the sample solution becomes clear, immediately add 5M sodium hydroxide solution to adjust the pH to 7.0, and dilute with water to 100mL. HPLC analysis of the diluted solution showed that the purities of the two epimers of imipenem impurity B were 26.2% and 35.3%, respectively, totaling 61.5%.

[0110] 2) Inject the crude imipenem impurity B solution into a dynamic axial compression column system, perform gradient elution, and collect the target component eluent; the elution conditions and elution gradient are the same as in Example 1.

[0111] 3) The collected solution was directly freeze-dried at low temperature. Freeze-drying curve:

[0112]

[0113] After lyophilization, the sample was weighed and analyzed. The impurity B of imipenem was 511 mg, the HPLC purity was 96.5%, and the yield was 51.1%.

[0114] Example 8

[0115] 1) The preparation of the crude imipenem impurity B solution was the same as in Example 1;

[0116] 2) Inject the crude imipenem impurity B solution into a dynamic axial compression column system, perform gradient elution, and collect the eluent of the target component;

[0117] Other conditions are the same as in Example 1.

[0118] Elution was performed using the following gradient elution program: initial elution separation and subsequent elution equilibration. The initial elution separation program was as follows: at 0 minutes, the volume ratio of mobile phase B was 5%; at 7 minutes, the volume ratio of mobile phase B increased to 8%; from 7.1 to 17 minutes, the volume ratio of mobile phase B increased from 12% to 30%; and from 17.1 to 22 minutes, the volume ratio of mobile phase B was maintained at 50%. After the initial elution separation, from 22.1 to 27 minutes, the volume ratio of mobile phase B was 5% for subsequent elution equilibration. The process was repeated, with initial elution separation followed by subsequent elution equilibration, for a total of 5 injections. This gradient could not effectively separate imipenem impurity B. Imipenem impurity B showed poor separation from other impurities, eluting at a retention time of approximately 5 minutes. The online preparation chromatogram is shown below. Figure 4 .

[0119] Example 9

[0120] 1) The preparation of the crude imipenem impurity B solution was the same as in Example 1;

[0121] 2) Inject the crude imipenem impurity B solution into a dynamic axial compression column system, perform gradient elution, and collect the eluent of the target component; experimental conditions are the same as in Example 1;

[0122] 3) The collected solution was distilled under reduced pressure in a 30°C water bath. The remaining solution was analyzed by HPLC, and the HPLC purity was 91.6%.

[0123] Example 10

[0124] 1) The preparation of the crude imipenem impurity B solution was the same as in Example 1;

[0125] 2) Inject the crude imipenem impurity B solution into a dynamic axial compression column system, perform gradient elution, and collect the eluent of the target component; experimental conditions are the same as in Example 1;

[0126] 3) The collected solution was directly freeze-dried at low temperature. Freeze-drying curve:

[0127]

[0128] After lyophilization, the sample was weighed and analyzed. The impurity B of imipenem was 552 mg, the combined HPLC purity was 92.1%, and the yield was 55.2%.

[0129] Comparative Example 1

[0130] 1.0 g of imipenem was dissolved in 2 L of 0.05 M sulfuric acid solution and stirred at room temperature for 1 hour. Solid barium sulfate was gradually added to the acidic solution to adjust the pH to 7. The solution was filtered, and the filtrate was analyzed using the HPLC detection method in the reference example. The purities of the two epimers of imipenem impurity B were 23.3% and 25.4%, respectively, totaling 48.7%. The HPLC analysis chromatograms are shown in the appendix. Figure 5 The peak labeled 1 / 2 corresponds to the two isomers of imipenem impurity B.

[0131] The filtrate was purified by HPLC under the following conditions: Vydac, C18 column, 25*1.0cm, 5μm, wavelength 215nm, injection volume: 1mL, flow rate: 1.0mL / min, elution gradient: 0-30min, acetonitrile volume ratio: 2-98%. The eluent with a retention time of 12.6min was collected. This method requires multiple enrichment steps, is time-consuming, and has low preparation efficiency. It can only yield the eluent for analytical detection, making it difficult to apply industrially.

[0132] Comparative Example 2

[0133] 1) The preparation of crude solution of imipenem impurity B was the same as in Comparative Example 1.

[0134] 2) Inject the crude imipenem impurity B solution into a dynamic axial compression column system, perform gradient elution, and collect the eluent of the target component; the elution conditions and gradient are the same as in Example 1, and the online preparation chromatogram is shown in [link to example]. Figure 6 .

[0135] 3) The prepared collected liquid was directly freeze-dried at low temperature, and the freeze-drying method was the same as in Example 1.

[0136] After lyophilization, the sample was weighed and analyzed. The amount of imipenem impurity B was 399 g, the HPLC purity was 96.8%, and the yield was 39.9%. The analytical chromatogram is shown below. Figure 7 The peak labeled 1 / 2 corresponds to the two isomers of imipenem impurity B.

Claims

1. A method for preparing imipenem impurity B, characterized in that, Includes the following steps: 1) Imipenem was added to water to obtain an imipenem suspension. Concentrated sulfuric acid was added dropwise while stirring continuously. After the solution became clear, the pH was adjusted to neutral with an alkaline solution and diluted with water to obtain a crude solution of imipenem impurity B. 2) Inject the crude imipenem impurity B solution into a dynamic axial compression column system, perform gradient elution, and collect the eluent of the target component; 3) Freeze-dry the eluent of the target component to obtain pure imipenem impurity B; ; In step 1), the mass-to-volume ratio of imipenem to concentrated sulfuric acid is 1:0.8-1.2, where mass is expressed in g and volume in mL; the alkaline solution in step 1) is selected from sodium hydroxide solution and potassium hydroxide solution; the concentration of the alkaline solution in step 1) is 0.5-5 mol / L. In step 2), the chromatographic column used for gradient elution is a Sepax HP C18 10μm 120 Å column. The mobile phase A in step 2) is purified water, and the mobile phase B is acetonitrile. The gradient elution in step 2) is performed according to the following gradient elution program: initial elution separation and subsequent elution equilibration. The initial elution separation program is as follows: at 0 minutes, the volume ratio of mobile phase B is 0%–2%; at 7 minutes, the volume ratio of mobile phase B increases to 2%–4%; from 7.1 to 17 minutes, the volume ratio of mobile phase B increases from 10%–15% to 20%–25%; from 17.1 to 22 minutes, the volume ratio of mobile phase B is maintained at 50%–55%; after the initial elution separation, from 22.1 to 27 minutes, the volume ratio of mobile phase B is maintained at 0%–2% for subsequent elution equilibration before re-injection. The process can be repeated: first, elute to equilibrium, then repeat the cycle; or, as described in step 2), the gradient elution can be performed according to the following gradient elution program: initial elution separation and subsequent elution equilibrium. The initial elution separation program is as follows: at 0 minutes, the volume ratio of mobile phase B is 3%–4%; at 7 minutes, the volume ratio of mobile phase B increases to 5%–6%; from 7.1 to 17 minutes, the volume ratio of mobile phase B increases from 10%–15% to 20%–25%; from 17.1 to 22 minutes, the volume ratio of mobile phase B is maintained at 50%–55%; after the initial elution separation is completed, from 22.1 to 27 minutes, the volume ratio of mobile phase B is maintained at 3%–4% for subsequent elution equilibrium, then the sample is injected again, and the process of initial elution separation and subsequent elution equilibrium is repeated.

2. The preparation method according to claim 1, characterized in that, In step 1), the mass-to-volume ratio of imipenem to water in the imipenem suspension is 1:40-60, where mass is expressed in g and volume in mL.

3. The preparation method according to claim 1, characterized in that, The freeze-drying curve described in step 3) is as follows: 。

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