A gas chromatographic method for determining amine impurities in sodium ibandronate

Abstract

This invention relates to the field of gas chromatography detection technology, and proposes a gas chromatography method for determining amine impurities in ibandronate sodium. The method uses gas chromatography to detect residual amine impurities in ibandronate sodium; the amine impurities include 3-methylaminopropionitrile, intermediate I, and N,N-dipentylmethylamine; intermediate I is 3-(N-methyl-N-n-pentylamino)propionitrile. This technical solution solves the problems of limited amine impurity detection, poor system applicability, and low sensitivity in related technologies for detecting amine impurities in ibandronate sodium.

Description

Technical Field

[0001] This invention relates to the field of gas chromatography detection technology, specifically to a gas chromatography method for determining amine impurities in sodium ibandronate. Background Technology

[0002] Existing methods for detecting amine impurities in sodium ibandronate all focus on detecting residues in the sodium ibandronate raw material. Direct use of these methods is crude, and their detection sensitivity (limit of detection) does not meet the requirements for solvent detection. Furthermore, existing methods have poor system applicability and do not meet the requirements for drug monitoring. Based on the chemical materials and reaction conditions used in the production of sodium ibandronate, such as those disclosed in the literature Zhu Jun, Zhao Hui, Xu Rui. Synthesis of Sodium Ibandronate [J]. Liaoning Chemical Industry, 2015, 44(11):1298-1299, the synthetic route is as follows: Starting with 3-methylaminopropionitrile, 3-(N-methyl-N-n-pentanamino)propionitrile and 3-(N-methyl-N-n-pentanamino)propionate are synthesized sequentially to finally obtain sodium ibandronate.

[0003]

[0004] Therefore, certain key starting materials (3-methylaminopropionitrile), intermediates (3-(N-methyl-N-n-pentanamino)propionitrile), and byproducts (N,N-dipentylmethylamine) may remain in the ibandronate sodium product, affecting the product quality of ibandronate sodium.

[0005] Currently, there is no known method for detecting amine impurities such as starting materials, intermediates, and byproducts in ibandronate sodium. Therefore, establishing a method capable of separating and detecting residual amine impurities (starting materials, intermediates, and byproducts) in ibandronate sodium would be of great significance for the quality control of ibandronate sodium raw materials. Summary of the Invention

[0006] This invention proposes a gas chromatography method for determining amine impurities in ibandronate sodium, which solves the problems of limited amine impurity detection, poor system applicability, and low sensitivity in related technologies for detecting amine impurities in ibandronate sodium.

[0007] The technical solution of the present invention is as follows:

[0008] This invention proposes a gas chromatography method for determining amine impurities in sodium ibandronate, using gas chromatography to detect residual amine impurities in sodium ibandronate;

[0009] The amine impurities include 3-methylaminopropionitrile, intermediate I, and N,N-dipentylmethylamine, with intermediate I being 3-(N-methyl-N-n-pentylamino)propionitrile.

[0010] As a further technical solution, the gas chromatography method is direct injection gas chromatography.

[0011] As a further technical solution, the injection port temperature for gas chromatography detection is 220℃, the detector temperature is 250℃, the split ratio is 8~12:1, the column flow rate is 1.4~1.6mL / min, and the injection volume is 1μL.

[0012] The gas chromatography detection method employs a gradient temperature increase: the initial temperature is 115~125℃, maintained for 5 minutes, and then increased to 220℃ at a rate of 38~42℃ / min, maintained for 10 minutes.

[0013] As a further technical solution, the chromatographic column used in the gas chromatography detection is a DB-624 column or a CP-Volamine column.

[0014] As a further technical solution, the chromatographic column is a CP-Volamine chromatographic column.

[0015] In this invention, a capillary column specifically designed for amine compounds was selected as the gas chromatography column. Sharper peak shapes can be obtained on this column, solving the problem of poor repeatability on ordinary chromatography columns.

[0016] As a further technical solution, the preparation of the test solution for gas chromatography detection is carried out by alkali extraction.

[0017] In this invention, because the solvent to be tested has a high boiling point and is alkaline, it forms a salt with sodium ibandronate and cannot volatilize. It is detected by headspace gas chromatography. After extraction, the residual substances can be extracted into the organic solvent, which can eliminate the interference of acidic main components and other by-products, and can also improve the recovery rate of residual solvent and the recovery rate of extraction.

[0018] The alkali extraction method includes the following steps: mixing sodium ibandronate with alkali solution and organic solvent, and taking the organic solvent layer after separation as the test solution.

[0019] As a further technical solution, the alkaline solution includes one of sodium bicarbonate solution, sodium carbonate solution, and sodium hydroxide solution;

[0020] The concentration of the alkaline solution is 1~3 mol / L;

[0021] The organic solvent includes one of dichloromethane, toluene, ethyl acetate, and n-hexane.

[0022] As a further technical solution, the alkaline solution is a sodium hydroxide solution;

[0023] The concentration of the alkaline solution is 3 mol / L;

[0024] The organic solvent is dichloromethane.

[0025] As a further technical solution, the mass-to-volume ratio of sodium ibandronate and alkaline solution is 1g:10~20mL.

[0026] As a further technical solution, the gas chromatography method includes the following steps:

[0027] Inject the test solution, reference solution, and blank solvent into the gas chromatograph and record the chromatograms. Calculate the contents of 3-methylaminopropionitrile, intermediate I, and N,N-dipentylmethylamine by peak area using the external standard method.

[0028] As a further technical solution, the preparation of the blank solvent includes the following steps: mixing the alkaline solution and the organic solvent, and taking the organic solvent layer after separation as the blank solvent.

[0029] As a further technical solution, the preparation of the reference solution includes the following steps:

[0030] S1. 3-Methylaminopropionitrile, intermediate I, N,N-dipentylmethylamine and organic solvent were mixed to obtain the reference standard stock solution;

[0031] S2. Mix the reference standard stock solution and the alkaline solution, and after separation, take the organic solvent layer as the reference standard solution.

[0032] As a further technical solution, the system suitability requirements of the gas chromatography method are as follows: in the chromatogram of the reference solution, the elution order is 3-methylaminopropionitrile, N,N-dipentylmethylamine, intermediate I, the theoretical plate number of each peak should not be less than 5000, and the resolution between each peak should not be less than 1.5.

[0033] Limits: Calculated by peak area using the external standard method, the starting material, intermediate I, and byproduct (N,N-dipentylmethylamine) shall not exceed 0.1%.

[0034] In this invention, when the conditions of alkali extraction, column flow rate, column temperature, injection port temperature, detector temperature, and gas chromatography column fluctuate within a certain range, the RSD values ​​of the peak areas of each analyte are all <5.0%; the resolution of each analyte is all >3.0; the theoretical plate number of each analyte is all >5000; and the relative deviations between the sample detection results under each changing condition and the detection results under the original conditions are all <5.0%. Therefore, the robustness of the analytical method of this invention meets the requirements when the parameters fluctuate within a certain range.

[0035] The working principle and beneficial effects of this invention are as follows:

[0036] In this invention, gas chromatography is used to detect amine impurities such as 3-methylaminopropionitrile, intermediate I, and N,N-dipentylmethylamine in sodium ibandronate. The detection method of this invention has good specificity. After eliminating the interference of conventional solvents, the separation of each analyte is high. Blank solvent, other materials, impurities, by-products, and sample solutions do not interfere with the determination at the retention times of each material.

[0037] Methodological validation showed that the optimized system met the requirements and could achieve the purpose of drug quality control.

[0038] The detection sensitivity is high: the detection limits for 3-methylaminopropionitrile, intermediate I, and N,N-dipentylmethylamine are 0.00093%, 0.00089%, and 0.00091%, respectively; the RSD values ​​of the peak areas of the limit-of-quantitation solutions are all <10% when the samples are injected repeatedly.

[0039] High accuracy of detection: The test results show that the average recovery rate of the sample is in the range of 90% to 105%, and the RSD value of the recovery rate at each concentration level is <5%. Attached Figure Description

[0040] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0041] Figure 1 This is the detection chromatogram of the blank solvent in Example 1 of the present invention;

[0042] Figure 2 This is the detection chromatogram of the reference solution in Example 1 of the present invention;

[0043] Figure 3 This is the detection chromatogram of the test solution in Example 1 of the present invention;

[0044] Figure 4 The graph shows the linearity and range test results of 3-methylaminopropionitrile in Example 1 of this invention;

[0045] Figure 5 The graph shows the linearity and range test results of N,N-dipentylmethylamine in Example 1 of this invention.

[0046] Figure 6 The graph shows the linearity and range test results of intermediate I in Embodiment 1 of the present invention. Detailed Implementation

[0047] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0048] In the following examples, iban sodium phosphate, raw material, batch number 230802, source: self-made;

[0049] Intermediate I is 3-(N-methyl-N-n-pentanamino)propionitrile, batch number 230301, purity 99.67%, source: self-made;

[0050] 3-Methylaminopropionitrile, batch number G2228362, content 98.975%, source: Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0051] N,N-Dipentylmethylamine, batch number 230904, content 99.745%, source: self-made;

[0052] The gas chromatograph is model 7820A.

[0053] Example 1: Determination of starting materials and intermediate residues in sodium ibandronate by gas chromatography

[0054] Chromatographic conditions

[0055] Chromatographic column: Capillary column for amine compound analysis (Agilent CP-Volamine, 30m × 0.32mm);

[0056] Temperature rise program: Start at 120℃, maintain for 5 minutes, then rise to 220℃ at a rate of 40℃ per minute and maintain for 10 minutes;

[0057] Inlet temperature: 220℃;

[0058] Detector temperature: 250℃;

[0059] The split ratio is 10:1;

[0060] Column flow rate: 1.5 mL / min;

[0061] Injection volume: 1 μL;

[0062] Hydrogen: 40 mL / min;

[0063] Air: 400 mL / min;

[0064] Purging: 20 mL / min;

[0065] 3 mol / L sodium hydroxide solution: Take 12 g of sodium hydroxide, place it in a 100 mL bottle, dissolve and dilute with water to the mark, and shake well.

[0066] Blank solvent: Take 5 mL of 3 mol / L sodium hydroxide solution, place it in a stoppered test tube, accurately add 10 mL of dichloromethane, shake well, let stand to allow the layers to separate, and take the dichloromethane layer.

[0067] Test solution: Weigh about 0.5 g of this product accurately, place it in a stoppered test tube, add 5 mL of 3 mol / L sodium hydroxide solution to dissolve it, accurately add 10 mL of dichloromethane, shake well, let stand to separate the layers, and take the dichloromethane layer.

[0068] Reference stock solution: Accurately weigh 25 mg each of 3-methylaminopropionitrile, intermediate I, and N,N-dipentylmethylamine, place them in the same 50 mL volumetric flask, dissolve and dilute to the mark with dichloromethane, shake well, accurately measure 5 mL, place it in a 50 mL volumetric flask, dilute to the mark with dichloromethane, and shake well.

[0069] Reference solution: Take 5 mL of 3 mol / L sodium hydroxide solution, place it in a stoppered test tube, accurately add 10 mL of the reference stock solution, shake well, let stand to allow the layers to separate, and take the dichloromethane layer.

[0070] Determination: Accurately measure blank solvent, test solution and reference solution, inject them into the gas chromatograph and record the chromatograms.

[0071] System suitability requirements: In the solution chromatogram, the elution order is 3-methylaminopropionitrile, N,N-dipentylmethylamine, intermediate I, the theoretical plate number of each peak should be not less than 5000, and the resolution between each peak should be not less than 1.5.

[0072] Limits: Calculated by peak area using the external standard method, the levels of 3-methylaminopropionitrile, intermediate I, and N,N-dipentylmethylamine shall not exceed 0.1%.

[0073] Calculation formula:

[0074]

[0075] In the formula, W 对 The sample weights (mg) of 3-methylaminopropionitrile, intermediate I, and N,N-dipentylmethylamine reference standards;

[0076] P: Purity of 3-methylaminopropionitrile, intermediate I and N,N-dipentylmethylamine reference standards.

[0077] A 对 Peak areas of 3-methylaminopropionitrile, intermediate I, and N,N-dipentylmethylamine in the reference solution;

[0078] V 对 The dilution factor of the reference solution;

[0079] A 样 Peak areas of 3-methylaminopropionitrile, intermediate I, and N,N-dipentylmethylamine in the test solution;

[0080] W 样 : Sample weight, mg;

[0081] V 样 : The dilution factor of the test solution.

[0082] Test results:

[0083] The chromatograms obtained from the detection of blank solvent, test solution, and reference solution are as follows: Figures 1-3 As shown.

[0084] The contents of 3-methylaminopropionitrile, intermediate I, and N,N-dipentylmethylamine were calculated by peak area using the external standard method. The results showed that none of them were detected, meaning that the contents of 3-methylaminopropionitrile, intermediate I, and N,N-dipentylmethylamine were less than 0.00093%, 0.0089%, and 0.00091%, respectively.

[0085] Experiment Example 1: Verification of the Test Method

[0086] 1.1 Specificity Test

[0087] 3 mol / L sodium hydroxide solution: Take 36 g of sodium hydroxide, add 300 mL of water to dissolve, and shake well.

[0088] Blank solvent: Take 5 mL of 3 mol / L sodium hydroxide solution, place it in a stoppered test tube, accurately add 10 mL of dichloromethane, shake well, let stand to allow the layers to separate, and take the dichloromethane layer.

[0089] N,N-Dipentylmethylamine reference stock solution: Accurately weigh 25 mg of N,N-dipentylmethylamine, place it in a 50 mL volumetric flask, dilute to the mark with dichloromethane, and shake well;

[0090] N,N-Dipentylmethylamine positioning solution: Accurately measure 1 mL of N,N-dipentylmethylamine reference stock solution, place it in a 10 mL volumetric flask, dilute to the mark with dichloromethane, and shake well;

[0091] 3-Methylaminopropionitrile reference stock solution: Accurately weigh 25 mg of 3-methylaminopropionitrile, place it in a 50 mL volumetric flask, dilute to the mark with dichloromethane, and shake well;

[0092] 3-Methylaminopropionitrile positioning solution: Accurately measure 1 mL of 3-methylaminopropionitrile reference stock solution, place it in a 10 mL volumetric flask, dilute to the mark with dichloromethane, and shake well;

[0093] Intermediate I reference stock solution: Accurately weigh 25 mg of intermediate I, place it in a 50 mL volumetric flask, dilute to the mark with dichloromethane, and shake well;

[0094] Intermediate I positioning solution: Accurately measure 1 mL of intermediate I stock solution reference standard, place it in a 10 mL volumetric flask, dilute to the mark with dichloromethane, and shake well;

[0095] Other positioning solutions: Accurately weigh 25 mg each of methanol, ethanol, acetone, N,N-dimethylformamide, benzene, toluene, 1-bromopentane, trimethyl phosphate, dimethyl phosphite, dimethylaminopropionitrile, and 3-aminopropionitrile, and place them in 25 mL volumetric flasks respectively. Dilute to the mark with dichloromethane and shake well to prepare stock solutions. Accurately measure 1 mL of each solution and place it in a 10 mL volumetric flask. Dilute to the mark with dichloromethane and shake well.

[0096] Mixed reference stock solution: Accurately measure 5 mL each of N,N-dipentylmethylamine stock solution, 3-methylaminopropionitrile stock solution, and intermediate I stock solution, place them in the same 50 mL volumetric flask, dilute to the mark with dichloromethane, and shake well.

[0097] Reference solution: Accurately measure 5 mL of 3 mol / L sodium hydroxide solution and place it in a stoppered test tube. Accurately add 10 mL of mixed reference stock solution, shake well, and let stand to allow the layers to separate. Take the dichloromethane layer.

[0098] Test solution: Weigh about 0.5 g of this product accurately, place it in a stoppered test tube, add 5 mL of 3 mol / L sodium hydroxide solution to dissolve it, accurately add 10 mL of dichloromethane, shake well, let stand to separate the layers, and take the dichloromethane layer.

[0099] The sample was injected and analyzed according to the chromatographic conditions in the specific implementation method, and the results are recorded in Table 1 below.

[0100] Table 1 Results of specificity test

[0101]

[0102] 1.2 Limit of Quantitation and Limit of Detection

[0103] Blank solvent: Take 5 mL of 3 mol / L sodium hydroxide solution, place it in a stoppered test tube, accurately add 10 mL of dichloromethane, shake well, let stand to allow the layers to separate, and take the dichloromethane layer.

[0104] Quantitation limit stock solutions: Accurately measure 20 mL each of N,N-dipentylmethylamine reference stock solution, 3-methylaminopropionitrile reference stock solution, and intermediate I reference stock solution, place them in a 200 mL volumetric flask, dilute to the mark with dichloromethane, and shake well to obtain the stock solutions; take 2.5 mL of the stock solutions, place them in a 50 mL volumetric flask, dilute to the mark with dichloromethane, and shake well; accurately measure 30 mL of the stock solutions, place them in a 50 mL volumetric flask, dilute to the mark with dichloromethane, and shake well.

[0105] Limit of Quantitation (LOQ) Solution: Accurately measure 5 mL of 3 mol / L sodium hydroxide solution and place it in a stoppered test tube. Accurately add 10 mL of the LOQ stock solution, shake well, and allow to stand to separate the layers. Take the dichloromethane layer. Prepare six parallel aliquots with a S / N ratio of approximately 10–20.

[0106] Detection limit stock solution: Accurately measure 6 mL of the quantitation limit stock solution, place it in a 20 mL volumetric flask, dilute to the mark with dichloromethane, and shake well.

[0107] Detection limit solution: Accurately measure 5 mL of 3 mol / L sodium hydroxide solution and place it in a stoppered test tube. Accurately add 10 mL of the detection limit stock solution, shake well, and allow to stand to separate the layers. Take the dichloromethane layer. Ensure the S / N ratio is approximately 3–10. Prepare three parallel aliquots.

[0108] Inject the limit of quantitation solution and the limit of detection solution separately, and analyze them according to the chromatographic conditions in the specific implementation method. The results are recorded in Table 2 below.

[0109] Table 2 Results of Limit of Quantitation and Limit of Detection Tests

[0110]

[0111] 1.3 Solution stability test

[0112] Blank solvent: Preparation method is the same as for specificity test;

[0113] Spiked test solution: Weigh approximately 0.5 g of this product accurately and place it in a stoppered test tube. Add 5 mL of 3 mol / L sodium hydroxide solution to dissolve it. Accurately add 10 mL of mixed reference stock solution (prepared in the same way as the specificity test), shake well, and let it stand to separate into layers. Take the dichloromethane layer.

[0114] Reference solution: Preparation method is the same as for specificity test.

[0115] Take the reference solution and the test solution, and inject them once at different time intervals. Analyze them according to the chromatographic conditions in the specific implementation method. The results are recorded in Table 3 below.

[0116] Table 3 Results of solution stability test

[0117]

[0118] 1.4 Linearity and Range

[0119] Take each impurity reference standard, dissolve it in dichloromethane, and gradually dilute it to prepare a series of reference standard mixed solutions with concentrations of 5%, 20%, 50%, 100%, 150%, and 200% of the limit of quantitation (LOQ). Inject and analyze the solutions according to the chromatographic conditions described in the specific implementation method. Perform linear regression with concentration on the x-axis and peak area on the y-axis, list the regression equation, and report the correlation coefficient, the percentage of the Y-axis intercept to 100% of the response value, and the response factor RSD. The results are recorded in Tables 4-6 below. Figures 4-6 As shown in the figure. The results indicate that the proposed method exhibits good linearity.

[0120] Table 4. Results of linearity and range tests for 3-methylaminopropionitrile.

[0121]

[0122] Table 5. Results of linearity and range tests for N,N-dipentylmethylamine

[0123]

[0124] Table 6. Results of linearity and range tests for intermediate I

[0125]

[0126] 1.5 Repeatability Test

[0127] Blank solvent: Take 5 mL of 3 mol / L sodium hydroxide solution, place it in a stoppered test tube, accurately add 10 mL of dichloromethane, shake well, let stand to allow the layers to separate, and take the dichloromethane layer.

[0128] Reference solution: Accurately measure 5 mL of 3 mol / L sodium hydroxide solution and place it in a stoppered test tube. Accurately add 10 mL of mixed reference stock solution (prepared in the same way as the specific test), shake well, and let stand to allow the layers to separate. Take the dichloromethane layer.

[0129] Test solution: Accurately weigh approximately 0.5 g of this product and place it in a stoppered test tube. Add 5 mL of 3 mol / L sodium hydroxide solution to dissolve it. Accurately add 10 mL of dichloromethane, shake well, and allow to stand to separate the layers. Take the dichloromethane layer. Prepare two parallel solutions.

[0130] Spiked test solution: Accurately measure 20 mL each of N,N-dipentylmethylamine reference stock solution, 3-methylaminopropionitrile reference stock solution, and intermediate I reference stock solution, place them in a 200 mL volumetric flask, dilute to the mark with dichloromethane, and shake well to prepare the stock solution; accurately weigh about 0.5 g of this product, place it in a stoppered test tube, add 5 mL of 3 mol / L sodium hydroxide solution to dissolve it, accurately add 10 mL of the stock solution, shake well, let it stand to separate the layers, take the dichloromethane layer, and prepare 6 parallel aliquots.

[0131] Inject the sample and analyze it according to the chromatographic conditions in the specific implementation method, record the chromatogram, and calculate the content, recovery rate and RSD value of each component peak using the external standard method. The results are recorded in Table 7 below.

[0132] Table 7 Repeatability Test Results

[0133]

[0134] 1.6 Accuracy Test

[0135] Blank solvent: Take 5 mL of 3 mol / L sodium hydroxide solution, place it in a stoppered test tube, accurately add 10 mL of dichloromethane, shake well, let stand to allow the layers to separate, and take the dichloromethane layer.

[0136] 50% reference standard stock solution: Same as linear - 50% stock solution.

[0137] 100% reference stock solution: Same linear - 100% stock solution.

[0138] 150% reference standard stock solution: same as linear - 150% stock solution.

[0139] Reference solution: Preparation method is the same as for repeatability test.

[0140] 50% spiked test solution: Accurately weigh approximately 0.5 g of this product and place it in a stoppered test tube. Add 5 mL of 3 mol / L sodium hydroxide solution to dissolve it. Accurately add 10 mL of 50% stock solution of the reference standard, shake well, and allow to stand to separate the layers. Take the dichloromethane layer. Prepare three parallel solutions.

[0141] 100% spiked test solution: Accurately weigh approximately 0.5 g of this product and place it in a stoppered test tube. Add 5 mL of 3 mol / L sodium hydroxide solution to dissolve it. Accurately add 10 mL of 100% stock solution of the reference standard, shake well, and allow to stand to separate the layers. Take the dichloromethane layer. Prepare three parallel solutions.

[0142] 150% spiked test solution: Accurately weigh approximately 0.5 g of this product and place it in a stoppered test tube. Add 5 mL of 3 mol / L sodium hydroxide solution to dissolve it. Accurately add 10 mL of 150% stock solution of the reference standard, shake well, and allow to stand to separate the layers. Take the dichloromethane layer. Prepare three parallel solutions.

[0143] Inject the sample and analyze it according to the chromatographic conditions in the specific implementation method, record the chromatogram, and calculate the content, recovery rate and RSD value of each impurity using the external standard method. The results are recorded in Tables 8 and 9 below.

[0144] Table 8 Accuracy Test Results

[0145]

[0146] Table 9 Accuracy Test Results

[0147]

[0148] 1.7 Intermediate Precision Test

[0149] Take the same batch of test samples, and have different analysts conduct experiments on different dates using different equipment, in accordance with the requirements of repeatability testing. Calculate the RSD of 12 results measured by the two researchers and record them in Table 10 below.

[0150] Table 10 Results of intermediate precision test

[0151]

[0152] 1.8 Durability Test

[0153] The robust chromatographic conditions are shown in Table 11 below.

[0154] Table 11 Robust Chromatographic Conditions

[0155]

[0156] Solution preparation

[0157] Blank solvent: Take 5 mL of 3 mol / L sodium hydroxide solution, place it in a stoppered test tube, accurately add 10 mL of dichloromethane, shake well, let stand to allow the layers to separate, and take the dichloromethane layer.

[0158] Reference stock solution: Take about 25 mg each of N,N-dipentylmethylamine reference standard, 3-methylaminopropionitrile reference standard and intermediate I reference standard, place them in the same 50 mL volumetric flask, dissolve and dilute to the mark with dichloromethane, shake well, accurately measure 5 mL, place it in a 50 mL volumetric flask, dilute to the mark with dichloromethane, and shake well.

[0159] Reference solution: Accurately measure 5 mL of 3 mol / L sodium hydroxide solution and place it in a stoppered test tube. Accurately add 10 mL of the reference stock solution, shake well, and let stand to allow the layers to separate. Take the dichloromethane layer.

[0160] Spiked test solution: Weigh approximately 0.5 g of this product accurately, place it in a stoppered test tube, add 5 mL of 3 mol / L sodium hydroxide solution to dissolve it, accurately add 10 mL of the reference stock solution, shake well, let stand to allow the layers to separate, and take the dichloromethane layer.

[0161] Measurement and Results

[0162] Inject the sample and analyze it according to the chromatographic conditions in the specific implementation method, record the chromatogram, and the results are recorded in Table 12.

[0163] Table 12 Durability Test Results

[0164]

[0165] 1.9 Evaluation and Conclusion of Verification Results

[0166] The validation results show that the method has good specificity, good linearity, good precision, high accuracy, solution stability, and good robustness. The results indicate that the method is suitable for the determination of 3-methylaminopropionitrile, intermediate I, and N,N-dipentylmethylamine in ibandronate sodium.

[0167] Experimental Example 2

[0168] The chromatographic column (CP-Volamine, 30m × 0.32mm) was replaced with a chromatographic column (DB-624, 30m × 0.25mm × 1.4μm); the remaining chromatographic conditions were the same as in Example 1, and 3-methylaminopropionitrile, intermediate I, and N,N-dipentylmethylamine in the sample were detected.

[0169] The results are shown in Table 13 below: Due to the alkaline nature of the analyte, the DB-624 column was used, resulting in poor reproducibility, unstable recovery, and RSD greater than 5%.

[0170] Table 13 Experimental Results

[0171]

[0172] Examples 2-4

[0173] The only difference between Examples 2-4 and Example 1 is the type of organic solvent used, as shown in Table 14.

[0174] Reference stock solution: Accurately weigh 12.5 mg each of 3-methylaminopropionitrile, intermediate I, and N,N-dipentylmethylamine, and place them in the same 25 mL volumetric flask. Dissolve and dilute to the mark with dichloromethane, toluene, ethyl acetate, and n-hexane respectively, and shake well. Accurately measure 2 mL of each solution into a 20 mL volumetric flask, and dilute to the mark with dichloromethane, toluene, ethyl acetate, and n-hexane respectively, and shake well.

[0175] Reference solution: Take 5 mL of 3 mol / L sodium hydroxide solution and place it in separate stoppered test tubes. Accurately add 10 mL of the stock solution of the reference solution prepared with each organic solvent, shake well, and allow to stand for layering. Take the organic layer for injection and detection. The recovery rate was calculated using dichloromethane as the reference solvent, and the results are shown in Table 14 below.

[0176] Table 14 Effect of different organic solvents on recovery rate

[0177]

[0178] It is evident that ethyl acetate and n-hexane are suitable organic solvents, but the recoveries of 3-methylaminopropionitrile, intermediate I, and N,N-dipentylmethylamine are all low. Toluene interferes with 3-methylaminopropionitrile, therefore dichloromethane is the most suitable organic solvent.

[0179] Examples 5-6

[0180] The only difference between Examples 5 and 6 and Example 1 is the type of alkali solution used, as shown in Table 15:

[0181] Reference solution: Accurately weigh 12.5 mg each of 3-methylaminopropionitrile, intermediate I, and N,N-dipentylmethylamine, place them in the same 25 mL volumetric flask, dissolve and dilute to the mark with dichloromethane, shake well, accurately measure 5 mL, place it in a 50 mL volumetric flask, dilute to the mark with dichloromethane, and shake well.

[0182] Spiked test solution: Accurately weigh approximately 0.5 g of this product and place it in three stoppered test tubes. Add 5 mL of saturated sodium bicarbonate, 3 mol / L sodium carbonate, and 3 mol / L sodium hydroxide solution to each tube respectively to dissolve them. Accurately add 10 mL of the reference solution, shake well, and allow to stand to separate the layers. Inject the organic layer. The results are shown in Table 15 below.

[0183] Table 15 Effect of Alkali Type on Recovery Rate

[0184]

[0185] It is evident that using sodium hydroxide to prepare the alkaline solution is more conducive to the recovery of 3-methylaminopropionitrile, intermediate I, and N,N-dipentylmethylamine.

[0186] Examples 7-8

[0187] The only difference between Examples 7-8 and Example 1 is the concentration of the sodium hydroxide solution, as shown in Table 16:

[0188] Reference solution: Accurately weigh 12.5 mg each of 3-methylaminopropionitrile, intermediate I, and N,N-dipentylmethylamine, place them in the same 25 mL volumetric flask, dissolve and dilute to the mark with dichloromethane, shake well, accurately measure 5 mL, place it in a 50 mL volumetric flask, dilute to the mark with dichloromethane, and shake well.

[0189] Spiked test solution: Weigh approximately 0.5 g of this product accurately and place it in four stoppered test tubes. Add 5 mL of water, 1 mol / L, 2 mol / L, and 3 mol / L sodium hydroxide solution respectively to dissolve the sample. Accurately add 10 mL of the reference solution, shake well, and allow to stand to separate the layers. Inject the organic layer. The results are shown in Table 16 below.

[0190] Table 16 Effect of different alkali concentrations on recovery rate

[0191]

[0192] It is evident that the recovery rates of 3-methylaminopropionitrile, intermediate I, and N,N-dipentylmethylamine are optimal when the sodium hydroxide solution concentration reaches 3 mol / L.

[0193] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A gas chromatographic method for determining amine impurities in sodium ibandronate, characterized in that, Gas chromatography was used to detect residual amine impurities in sodium ibandronate; The amine impurities are 3-methylaminopropionitrile, intermediate I, and N,N-dipentylmethylamine; The intermediate I is 3-(N-methyl-N-n-pentanamino)propionitrile; The test solution is prepared by alkali extraction during gas chromatography detection. The alkali extraction method includes the following steps: mixing sodium ibandronate with alkali solution and organic solvent, and taking the organic solvent layer after separation as the test solution. The alkaline solution is a sodium hydroxide solution; The organic solvent is dichloromethane; The gas chromatography column used for detection is a CP-Volamine column. The concentration of the alkaline solution is 3 mol / L.

2. The gas chromatography method for determining amine impurities in sodium ibandronate according to claim 1, characterized in that, The gas chromatography method described is direct injection gas chromatography.

3. The gas chromatography method for determining amine impurities in sodium ibandronate according to claim 1, characterized in that, The injection port temperature for gas chromatography detection is 220℃, the detector temperature is 250℃, the split ratio is 8~12:1, the column flow rate is 1.4~1.6mL / min, and the injection volume is 1μL. The gas chromatography detection method employs a gradient temperature increase: the initial temperature is 115~125℃, maintained for 5 minutes, and then increased to 220℃ at a rate of 38~42℃ / min, maintained for 10 minutes.

4. The gas chromatography method for determining amine impurities in sodium ibandronate according to claim 1, characterized in that, The mass-to-volume ratio of sodium ibandronate and alkaline solution is 1g:10~20mL.

5. The gas chromatography method for determining amine impurities in sodium ibandronate according to claim 1, characterized in that, Includes the following steps: Inject the test solution, reference solution, and blank solvent into the gas chromatograph and record the chromatograms. Calculate the contents of 3-methylaminopropionitrile, intermediate I, and N,N-dipentylmethylamine by peak area using the external standard method.

6. The gas chromatography method for determining amine impurities in sodium ibandronate according to claim 5, characterized in that, The preparation of the blank solvent includes the following steps: mixing the alkaline solution and the organic solvent, and taking the organic solvent layer after separation as the blank solvent.

7. The gas chromatography method for determining amine impurities in sodium ibandronate according to claim 6, characterized in that, The preparation of the reference solution includes the following steps: S1. 3-Methylaminopropionitrile, intermediate I, N,N-dipentylmethylamine and organic solvent were mixed to obtain the reference standard stock solution; S2. Mix the reference standard stock solution and the alkaline solution, and after separation, take the organic solvent layer as the reference standard solution.

Images