Gas chromatography separation and detection method for related substances of N-methyl-4-piperidone as starting material of pimavanserin

Abstract

The invention belongs to the technical field of pharmaceutical analysis, and relates to a gas chromatographic separation and detection method for related substances of N-methyl-4-piperidone as a pimavanserin starting material. According to the method, a capillary gas chromatographic column with 6% cyanopropyl / phenyl and 94% polydimethylsiloxane as stationary phases is adopted, a direct liquid injection mode is adopted, synchronous analysis of a plurality of related substances (multiple boiling point spans) in a starting material is achieved, the separation degree of each component peak and an adjacent chromatographic peak is larger than 1.5, the detection process is easy and convenient to operate, and the method is suitable for industrial production.

Description

Technical Field

[0001] This application belongs to the field of pharmaceutical analysis technology and relates to a gas chromatography separation and detection method for related substances of N-methyl-4-piperidinone in pimovaserine starting material. Background Technology

[0002] Pimavanserin tartrate (brand name Nuplazid) is used for the specific treatment of hallucinations and delusions associated with Parkinson's disease psychosis (PDP). This drug selectively acts on central 5-HT2A receptors, significantly reducing dopaminergic system interference. Clinical trials have shown that its symptom relief rate is 26% higher than that of conventional drugs, without increasing the risk of motor function deterioration. The 2021 edition of the "Chinese Guidelines for the Treatment of Parkinson's Disease (4th Edition)" has listed pimavanserin as a usable drug for treating PDP.

[0003] N-Methyl-4-piperidinone is a key starting material for the synthesis of pimova serine tartrate and is an important pharmaceutical intermediate with wide applications in drug synthesis. There are various methods for its preparation. Commercially available N-methyl-4-piperidinone (CAS No.: 1445-73-4) is mainly prepared from methyl acrylate and methylamine gas via Michael addition, Dieckmann cyclization, and decarboxylation reactions. According to the chemical reaction process, impurities in N-methyl-4-piperidinone may include, but are not limited to, the following compounds:

[0004]

[0005] The purification of N-methyl-4-piperidinone and these impurities is quite difficult. The introduced impurities are transferred to the intermediates and finished products in the preparation of pimova serin tartrate, and participate in subsequent reactions to generate new impurity derivatives, which brings risks and challenges to the quality control of pimova serin tartrate.

[0006] Currently, there are no publicly available methods for detecting impurities in N-methyl-4-piperidinone in the literature or patents. This invention establishes a method for separating and detecting N-methyl-4-piperidinone and its impurities through gas chromatography, and further optimizes the gas chromatography conditions to solve the problem of simultaneous analysis of impurities with multiple boiling point ranges in the starting material. Summary of the Invention

[0007] Regarding the current purification issues, one of the objectives of this application is to provide a gas chromatography separation and detection method for related substances of N-methyl-4-piperidinone in pimovaserin starting material. The method uses gas chromatography (GC) and a specific chromatographic column and programmed temperature strategy to separate four impurities with a large boiling point range in one step, ensuring baseline separation between the main component N-methyl-4-piperidinone and the impurities, and meeting the sensitivity requirements for impurity control in the starting material.

[0008] This application provides a gas chromatography separation and detection method for related substances of N-methyl-4-piperidinone, a starting material of pimova serin. The gas chromatography separation and detection method uses a capillary gas chromatography column, split injection, programmed temperature rise, a flame ionization detector, a detector temperature of 240-260℃, and an injection port temperature of 240-250℃.

[0009] In some embodiments of this application, the capillary gas chromatography column is a DB-624 gas chromatography column with 6% cyanopropyl / phenyl and 94% polydimethylsiloxane as the stationary phase, or any one of the following capillary gas chromatography columns with stationary phases of similar polarity: AT-624, Rtx-624, PE-624, 007-624, 007-502, CP-624, ZB-624, and VF-624ms; preferably, the capillary gas chromatography column is a DB-624 gas chromatography column.

[0010] In some embodiments of this application, the optimized column and high-purity nitrogen flow rate contribute to baseline separation and a high theoretical plate number. Combined with multi-stage temperature programming, this improves separation efficiency. The DB-624 column, with 6% cyanopropyl / phenyl and 94% polydimethylsiloxane as the stationary phase, possesses both polar and non-polar separation capabilities, enhancing the differentiation of impurities with different polarities. The specific nitrogen flow rate balances separation efficiency and analysis speed, reduces peak diffusion, increases the theoretical plate number, and ensures the resolution of adjacent peaks. The polarity balance of the DB-624 column, combined with multi-stage temperature programming, enables the simultaneous separation of impurities with boiling point spans >170℃, replacing traditional stepwise detection and improving separation efficiency.

[0011] In some embodiments of this application, the specific process of the temperature rise is as follows: the initial temperature is 30-40℃ and held for 8-12 minutes, then the temperature is increased to 198-202℃ at 14-16℃ / min and held for 1-3 minutes, and then the temperature is increased to 250℃ at 28-32℃ / min and held for 34-36 minutes.

[0012] In some embodiments of this application, a multi-stage programmed temperature rise is used to cover a boiling point range from 80°C to >300°C, overcoming the shortcomings of traditional methods that require step-by-step detection. The initial low temperature prolongs the retention time of low-boiling-point impurities (such as methyl acrylate), avoiding peak overlap; medium-speed heating separates medium-boiling-point components (such as the main component N-methyl-4-piperidinone); and high-speed heating elutes high-boiling-point impurities (such as 3,3'-methylazonium dimethoxymethylpropionamide). Through multi-stage programmed temperature rise, a single run covers a wide boiling point range, avoiding the cumbersome step-by-step detection of traditional methods.

[0013] In some embodiments of this application, the gas chromatographic separation and detection method for related substances of the pimova serin starting material N-methyl-4-piperidinone includes the following steps:

[0014] S1. Preparation: Set chromatographic conditions and equilibrate the column to the initial temperature; prepare blank solution, mixed control solution, sensitivity solution, test solution, and each positioning solution for later use.

[0015] S2. Injection: Inject blank solution, mixed control solution, sensitivity solution, test solution and each positioning solution into the gas chromatograph, and analyze according to the chromatographic conditions to obtain the chromatogram;

[0016] S3. Analysis: Analyze the chromatogram to obtain information such as the retention time, relative retention time, USP resolution, and USP theoretical plate number of each impurity, and determine the separation status and sensitivity of N-methyl-4-piperidinone and its related substances.

[0017] In some embodiments of this application, the chromatographic conditions are as follows: the chromatographic column is a DB-624 gas chromatographic column with dimensions of 30m × 320μm and a diameter of 1.8μm; the detector is a flame ionization detector with a temperature of 240-260℃; the injection port temperature is 240-250℃ with a split ratio of 10-100:1; the injection volume is 0.5-1μL; the carrier gas flow rate is 0.8-5mL / min; and the temperature program is as follows: an initial temperature of 30-40℃ held for 8-12 min, increased to 198-202℃ at 14-16℃ / min and held for 1-3 min, and increased to 250℃ at 28-32℃ / min and held for 34-36 min.

[0018] In some embodiments of this application, a split ratio of 10-100:1 combined with a low injection volume of 0.5-1 μL avoids column overload and ensures the detection of trace impurities, thereby improving sensitivity. A split ratio of 10-100:1 reduces the amount of sample entering the column, preventing excessively high concentrations of the main component from causing column overload, while simultaneously focusing trace impurities through splitting. The 0.5-1 μL injection volume reduces baseline noise, and combined with the high response characteristics of the FID detector, ensures that a 0.1 mg / mL sensitivity solution still satisfies S / N > 10.

[0019] In some embodiments of this application, the blank solution is chloroform.

[0020] In some embodiments of this application, the mixed reference solution is prepared by dissolving N-methyl-4-piperidinone, 4-piperidinone, 3,3'-methylazadiylbis(methacrylamide), dimethyl 3,3'-(methylazadiyl)dipropionate and methyl acrylate reference standards in chloroform to prepare a solution containing 0.25 mg / mL of each of the N-methyl-4-piperidinone-related substances per 1 mL.

[0021] In some embodiments of this application, the sensitivity solution is prepared by taking a mixed reference solution, dissolving it in chloroform, and preparing a solution containing 0.1 mg / mL of each N-methyl-4-piperidinone related substance per 1 mL.

[0022] In some embodiments of this application, the test solution is prepared by directly injecting N-methyl-4-piperidinone.

[0023] In some embodiments of this application, the positioning solutions include N-methyl-4-piperidinone solution, methyl acrylate solution, dimethyl 3,3'-(methylazadiyl)dipropionate solution, 3,3'-methylazadiylbis(methylpropionamide) solution, and 4-piperidinone solution.

[0024] In some embodiments of this application, the method for preparing the N-methyl-4-piperidinone solution is as follows: accurately weigh N-methyl-4-piperidinone reference standard, dissolve it in chloroform, and prepare a solution containing 10 mg of N-methyl-4-piperidinone per 1 mL.

[0025] In some embodiments of this application, the methyl acrylate solution is prepared by accurately weighing methyl acrylate reference standard, dissolving it in chloroform, and preparing a solution containing 10 mg of methyl acrylate per 1 mL.

[0026] In some embodiments of this application, the method for preparing the 3,3'-(methylazadiyl)dipropionate dimethyl ester solution is as follows: accurately weigh the 3,3'-(methylazadiyl)dipropionate dimethyl ester reference standard, dissolve it in chloroform, and prepare a solution containing 10 mg of 3,3'-(methylazadiyl)dipropionate dimethyl ester per 1 mL.

[0027] In some embodiments of this application, the 3,3'-methylazinedimethoxymethylpropionamide solution is prepared by accurately weighing 3,3'-methylazinedimethoxymethylpropionamide reference standard, dissolving it in chloroform, and preparing a solution containing 10 mg of 3,3'-methylazinedimethoxymethylpropionamide per 1 mL.

[0028] In some embodiments of this application, the 4-piperidinone solution is prepared by accurately weighing 4-piperidinone reference standard, dissolving it in chloroform, and preparing a solution containing 0.25 mg of 4-piperidinone per 1 mL.

[0029] Compared with the prior art, this application achieves at least the following technical effects:

[0030] This invention solves the problem of separation and detection of N-methyl-4-piperidinone and related substances in pimova serin starting material, which is beneficial to the quality control of pimova serin.

[0031] This invention provides for the first time a simultaneous GC detection scheme for four key impurities in N-methyl-4-piperidinone, which covers a wide boiling point range in a single run, avoiding the cumbersome step-by-step detection of traditional methods.

[0032] This invention has broad-spectrum separation capability. Through multi-stage programmed heating, the total running time is low, and it covers a boiling point range of 80℃ to >300℃, thus solving the defect of traditional methods that require step-by-step detection.

[0033] This invention features high sensitivity, using a split ratio of 10-100:1 combined with a low injection volume of 0.5-1 μL to avoid column overload and ensure the detection of trace impurities. Attached Figure Description

[0034] Figure 1 This is the chromatogram of the blank solution in Example 1;

[0035] Figure 2 This is the chromatogram of the mixed reference solution in Example 1;

[0036] Figure 3 This is the chromatogram of the sensitivity solution in Example 1;

[0037] Figure 4 This is the chromatogram of the methyl acrylate positioning solution in Example 1;

[0038] Figure 5 This is the chromatogram of the N-methyl-4-piperidinone localization solution in Example 1;

[0039] Figure 6 This is the chromatogram of the 4-piperidinone localization solution in Example 1;

[0040] Figure 7 This is the chromatogram of the dimethyl 3,3'-methylazadimethyldipropionate localization solution in Example 1;

[0041] Figure 8 This is the chromatogram of the 3,3'-methylazinedimethoxymethylpropionamide localization solution in Example 1;

[0042] Figure 9This is the chromatogram of the test solution in Example 1;

[0043] Figure 10 This is the chromatogram of the test solution in Example 2;

[0044] Figure 11 This is the chromatogram of the blank solution in Example 3;

[0045] Figure 12 This is the chromatogram of the mixed reference solution in Example 3;

[0046] Figure 13 This is the chromatogram of the methyl acrylate positioning solution in Example 3;

[0047] Figure 14 This is the chromatogram of the N-methyl-4-piperidinone localization solution in Example 3;

[0048] Figure 15 This is the chromatogram of the 4-piperidinone localization solution in Example 3;

[0049] Figure 16 This is the chromatogram of the 3,3'-methylazadimethyldipropionate dimethyl ester positioning solution in Example 3;

[0050] Figure 17 This is the chromatogram of the 3,3'-methylazinedimethoxymethylpropionamide positioning solution in Example 3. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below. However, it should be understood that the description herein is merely illustrative and not intended to limit the scope of the invention.

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the invention. All reagents and instruments used herein are commercially available, and the characterization methods involved are described in relevant prior art and will not be repeated herein.

[0053] Example 1

[0054] This embodiment provides a gas chromatography method for the separation and detection of related substances in pimova serin starting material N-methyl-4-piperidinone, the specific steps of which are as follows:

[0055] S1. Preparation: Set chromatographic conditions and equilibrate the column to the initial temperature; prepare blank solution, mixed control solution, sensitivity solution, test solution, and each positioning solution for later use.

[0056] S2. Injection: Inject blank solution, mixed control solution, sensitivity solution, test solution and each positioning solution into the gas chromatograph, and analyze according to the chromatographic conditions to obtain the chromatogram;

[0057] S3. Analysis: Analyze the chromatogram to obtain information such as the retention time, relative retention time, USP resolution, and USP theoretical plate number of each impurity, and determine the separation status and sensitivity of N-methyl-4-piperidinone and its related substances.

[0058] The chromatographic conditions were as follows: the column was a DB-624 gas chromatographic column with dimensions of 30m × 320μm and a diameter of 1.8μm; the detector was a flame ionization detector with a temperature of 260℃; the injection port temperature was 250℃ with a split ratio of 100:1; the injection volume was 1μL; the carrier gas flow rate was 1.0mL / min; and the temperature program was as follows: an initial temperature of 35℃ held for 10min, then increased to 200℃ at 15℃ / min and held for 2min, and finally increased to 250℃ at 30℃ / min and held for 35min.

[0059] The blank solution is chloroform.

[0060] The mixed reference solution is prepared by dissolving N-methyl-4-piperidinone, 4-piperidinone, 3,3'-methylazadiylbis(methacrylamide), dimethyl 3,3'-(methylazadiyl)dipropionate and methyl acrylate reference standards in chloroform to prepare a solution containing 0.25 mg / mL of each N-methyl-4-piperidinone-related substance per mL.

[0061] The sensitivity solution is prepared by dissolving the mixed reference solution in chloroform to prepare a solution containing 0.1 mg / mL of each N-methyl-4-piperidinone-related substance per 1 mL.

[0062] The test solution was prepared by directly injecting N-methyl-4-piperidinone. (The test sample was from Anhui Dexinjia Biomedical Co., Ltd., batch number NMD-230201)

[0063] The positioning solutions include N-methyl-4-piperidinone solution, methyl acrylate solution, dimethyl 3,3'-(methylazadiyl)dipropionate solution, 3,3'-methylazadiylbis(methylpropionamide) solution, and 4-piperidinone solution.

[0064] The method for preparing the N-methyl-4-piperidinone solution is as follows: accurately weigh N-methyl-4-piperidinone reference standard, dissolve it in chloroform, and prepare a solution containing 10 mg of N-methyl-4-piperidinone per 1 mL.

[0065] The methyl acrylate solution is prepared by accurately weighing methyl acrylate reference standard, dissolving it in chloroform, and preparing a solution containing 10 mg of methyl acrylate per 1 mL.

[0066] The method for preparing the 3,3'-(methylazadiyl)dipropionate dimethyl ester solution is as follows: accurately weigh the 3,3'-(methylazadiyl)dipropionate dimethyl ester reference standard, dissolve it in chloroform, and prepare a solution containing 10 mg of 3,3'-(methylazadiyl)dipropionate dimethyl ester per 1 mL.

[0067] The method for preparing the 3,3'-methylazinedimethoxymethylpropionamide solution is as follows: accurately weigh the 3,3'-methylazinedimethoxymethylpropionamide reference standard, dissolve it in chloroform, and prepare a solution containing 10 mg of 3,3'-methylazinedimethoxymethylpropionamide per 1 mL.

[0068] The 4-piperidinone solution is prepared by accurately weighing 4-piperidinone reference standard, dissolving it in chloroform, and preparing a solution containing 0.25 mg of 4-piperidinone per 1 mL.

[0069] See blank solution chromatogram. Figure 1 .from Figure 1 It can be seen that the blank solution does not interfere with the retention times of the peaks of each impurity.

[0070] Chromatogram of the mixed reference solution, see Figure 2 Information such as retention time, relative retention time, USP separation degree, and USP theoretical plate number for each impurity is shown in Table 1.

[0071] Table 1 Summary of chromatographic results for mixed reference solutions

[0072]

[0073] Depend on Figure 2 As shown in Table 1, in the mixed reference solution, the resolution (Rs) between adjacent chromatographic peaks is greater than 1.5, and the theoretical plate number (N) is ≥5000 (based on the N-methyl-4-piperidone peak).

[0074] Sensitivity solution chromatogram, see Figure 3 The results of sensitivity solution chromatography are summarized in Table 2.

[0075] Table 2 Summary of sensitivity solution chromatography results

[0076]

[0077] Depend on Figure 3 As shown in Table 2, the signal-to-noise ratio (s / n) of each impurity chromatographic peak in the sensitivity solution is greater than 10, which can guarantee the detection of impurities.

[0078] Chromatograms of each localization solution are shown below. Figures 4-8 The chromatographic results of each localization solution are summarized in Table 3.

[0079] Table 3 Summary of chromatographic results for each localization solution

[0080]

[0081]

[0082] Depend on Figures 4-8 As shown in Table 3, the retention times of the chromatographic peaks in each positioning solution are consistent with the retention times of the chromatographic peaks in the mixed reference solution, indicating that the peak names are correctly matched.

[0083] The chromatogram of the test solution is shown in [reference]. Figure 9 The chromatographic results of the test solution are summarized in Table 4.

[0084] Table 4 Summary of chromatographic results of the test sample solution

[0085]

[0086] Depend on Figure 9 As shown in Table 4, the peaks in the chromatogram of the test solution are separated at the baseline, which can be used for the detection of related substances in N-methyl-4-piperidinone, the starting material of pimova serin.

[0087] Example 2

[0088] The difference between this embodiment and Example 1 is that the test sample N-methyl-4-piperidinone was from Anhui Dexinjia Biomedical Co., Ltd., batch number NMD-221101.

[0089] The chromatogram of the test solution is shown in [reference]. Figure 10 The chromatographic results of the test solution are summarized in Table 5.

[0090] Table 5 Summary of chromatographic results of the test sample solutions

[0091]

[0092]

[0093] Depend on Figure 10 As shown in Table 5, the peaks in the chromatogram of the test solution are separated at the baseline, which can be used for the detection of related substances in N-methyl-4-piperidinone, the starting material of pimova serin.

[0094] Example 3

[0095] The difference between this embodiment and Example 1 is as follows: the chromatographic conditions are as follows: the chromatographic column is a gas chromatographic column SE-54 with dimensions of 30m × 320μm and 1.0μm; the detector is a flame ionization detector with a temperature of 260℃; the injection port temperature is 250℃ with a split ratio of 100:1; the injection volume is 1μL; the carrier gas flow rate is 1.0mL / min; and the temperature program is as follows: the initial temperature is 30℃ and held for 22min, then increased to 260℃ at a rate of 20℃ / min and held for 25min.

[0096] See blank solution chromatogram. Figure 11 The chromatographic results are shown in Table 6; the chromatogram of the mixed reference solution is shown in Table 6. Figure 12 Information on retention times, relative retention times, USP resolution, and USP theoretical plate number for each impurity is shown in Table 7; chromatograms of each targeted solution are shown in [Table 7]. Figures 13-17 The chromatographic results of each positioning solution are summarized in Table 8.

[0097] Table 6 Summary of Chromatographic Results for Blank Solution

[0098]

[0099] Table 7 Summary of chromatographic results for mixed reference solutions

[0100]

[0101]

[0102] Table 8 Summary of chromatographic results for each localization solution

[0103]

[0104] Experiments showed that 4-piperidinone, one of the separated substances, could not be completely dissolved by common laboratory solvents, while chloroform could dissolve all impurities in this experiment; therefore, chloroform is the preferred solvent. Figure 11-17 As can be seen from Table 6-8, the blank solution peak overlaps with the methyl acrylate peak, while the chromatographic peaks of the other related substances reach baseline separation. The overlap between the blank solution peak and the methyl acrylate peak indicates that the methyl acrylate cannot be accurately located, suggesting that the chromatographic conditions are not suitable for the separation of related substances in N-methyl-4-piperidinone.

[0105] The applicant declares that this application illustrates a gas chromatographic separation and detection method for related substances of N-methyl-4-piperidinone, a starting material of pimova serin, through the above embodiments. However, this application is not limited to the above embodiments, i.e., it does not mean that this application must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvements to this application, equivalent substitutions of raw materials for the product, addition of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of this application.

[0106] The preferred embodiments of this application have been described in detail above. However, this application is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this application, various simple modifications can be made to the technical solution of this application, and these simple modifications all fall within the protection scope of this application.

[0107] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable way without contradiction. In order to avoid unnecessary repetition, this application will not describe the various possible combinations separately.

Claims

1. A gas chromatographic separation and detection method for related substances of N-methyl-4-piperidinone from pimova serin starting material, characterized in that, The gas chromatography separation and detection method uses a capillary gas chromatography column, employs split injection, programmed temperature ramping, and a flame ionization detector with a detector temperature of 240-260℃ and an injection port temperature of 240-250℃. The capillary gas chromatography column is a DB-624 column with a stationary phase of 6% cyanopropyl / phenyl and 94% polydimethylsiloxane, or any one of the following capillary gas chromatography columns with similar polarity: AT-624, Rtx-624, PE-624, 007-624, 007-502, CP-624, ZB-624, or VF-624ms.

2. The gas chromatographic separation and detection method for related substances of N-methyl-4-piperidinone from pimova serin starting material according to claim 1, characterized in that, The specific temperature rise procedure is as follows: the initial temperature is 30-40℃ and held for 8-12 minutes, then increased to 198-202℃ at 14-16℃ / min and held for 1-3 minutes, and finally increased to 250℃ at 28-32℃ / min and held for 34-36 minutes.

3. The gas chromatographic separation and detection method for related substances of N-methyl-4-piperidinone from pimova serin starting material according to claim 2, characterized in that, The N-methyl-4-piperidinone-related substances include at least N-methyl-4-piperidinone, and also include one or more impurities selected from 4-piperidinone, 3,3'-methylazadiylbis(meth)propionamide, dimethyl 3,3'-(methylazadiyl)dipropionate, and methyl acrylate.

4. The gas chromatographic separation and detection method for related substances of N-methyl-4-piperidinone from pimova serin starting material according to claim 3, characterized in that, Includes the following steps: S1. Preparation: Set chromatographic conditions and equilibrate the column to the initial temperature; Prepare blank solution, mixed control solution, sensitivity solution, test solution, and each positioning solution for later use; S2. Injection: Inject blank solution, mixed control solution, sensitivity solution, test solution and each positioning solution into the gas chromatograph, and analyze according to the chromatographic conditions to obtain the chromatogram; S3. Analysis: Analyze the chromatogram to obtain information such as the retention time, relative retention time, USP resolution, and USP theoretical plate number of each impurity, and determine the separation status and sensitivity of N-methyl-4-piperidinone and its related substances.

5. The gas chromatographic separation and detection method for related substances of N-methyl-4-piperidinone from pimova serin starting material according to claim 4, characterized in that, The chromatographic conditions were as follows: the column was a DB-624 gas chromatographic column with dimensions of 30m × 320μm and a diameter of 1.8μm; the detector was a flame ionization detector with a temperature of 240-260℃; the injection port temperature was 240-250℃ with a split ratio of 10-100:1; the injection volume was 0.5-1μL; the carrier gas flow rate was 0.8-5mL / min; and the temperature program was as follows: an initial temperature of 30-40℃ held for 8-12 min, then increased to 198-202℃ at 14-16℃ / min and held for 1-3 min, and finally increased to 250℃ at 28-32℃ / min and held for 34-36 min.

6. The gas chromatographic separation and detection method for related substances of N-methyl-4-piperidinone from pimova serin starting material according to claim 4, characterized in that, The blank solution is chloroform.

7. The gas chromatographic separation and detection method for related substances of N-methyl-4-piperidinone from pimova serin starting material according to claim 6, characterized in that, The mixed reference solution is prepared by dissolving N-methyl-4-piperidinone, 4-piperidinone, 3,3'-methylazadiylbis(methacrylamide), dimethyl 3,3'-(methylazadiyl)dipropionate and methyl acrylate reference standards in chloroform to prepare a solution containing 0.25 mg / mL of each N-methyl-4-piperidinone-related substance per mL.

8. The gas chromatographic separation and detection method for related substances of N-methyl-4-piperidinone from pimova serin starting material according to claim 7, characterized in that, The sensitivity solution is prepared by dissolving the mixed reference solution in chloroform to prepare a solution containing 0.1 mg / mL of each N-methyl-4-piperidinone-related substance per 1 mL.

9. The gas chromatographic separation and detection method for related substances of N-methyl-4-piperidinone from pimova serin starting material according to claim 8, characterized in that, The positioning solutions include N-methyl-4-piperidinone solution, methyl acrylate solution, dimethyl 3,3′-(methylazadiyl)dipropionate solution, 3,3′-methylazadiylbis(methylpropionamide) solution, and 4-piperidinone solution.

10. The application of a gas chromatographic separation and detection method for related substances of N-methyl-4-piperidinone from pimovaserin starting material according to any one of claims 1 to 9 in the field of pharmaceutical analysis.

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