Gas chromatography method for determining amine impurities in sodium ibandronate

Abstract

The invention relates to the technical field of gas chromatography detection, and provides a gas chromatography method for determining amine impurities in sodium ibandronate, and the gas chromatography method is adopted to detect the residual amine impurities in sodium ibandronate. The amine impurities comprise 3-methylamino propionitrile, an intermediate I and N, N-dipentylmethylamine; the intermediate I is 3-(N-methyl-N-n-pentylamino) propionitrile. According to the technical scheme, the problems that the detected amine impurities are single, the system applicability is poor and the sensitivity is low when the amine impurities in the sodium ibandronate are detected in the prior art are solved.

Description

Technical Field

[0001] The invention relates to the technical field of gas chromatography detection, and in particular to a gas chromatography method for determining amine impurities in ibandronate sodium. Background Art

[0002] The methods for detecting amine impurities in sodium ibandronate in the prior art are all to detect the residues of the raw materials of sodium ibandronate. If used directly, the methods are rough and the detection sensitivity (detection limit) cannot meet the requirements of solvent detection. At the same time, the existing methods have poor system applicability and do not meet the requirements of drug monitoring. According to the chemical materials and reaction conditions used in the production process of sodium ibandronate, such as the document Zhu Jun, Zhao Hui, Xu Rui. Synthesis of sodium ibandronate [J]. Liaoning Chemical Industry, 2015, 44 (11): 1298-1299., 3-methylaminopropionitrile is used as the starting material to synthesize 3-(N-methyl-N-n-pentylamino) propionitrile and 3-(N-methyl-N-n-pentylamino) propionic acid hydrochloride in sequence, and finally sodium ibandronate is prepared. The synthesis route is:

[0003] Therefore, certain key starting materials (3-methylaminopropionitrile), intermediates (3-(N-methyl-N-n-pentylamino)propionitrile), and by-products (N,N-dipentylmethylamine) may still remain in the ibandronate sodium product, affecting the product quality of ibandronate sodium.

[0004] There is no method for detecting amine impurities such as residual starting materials, intermediates and by-products in ibandronate sodium in the prior art. Therefore, establishing a determination method capable of separating and detecting residual amine impurities (starting materials, intermediates and by-products) in ibandronate sodium will be of great significance for the quality control of ibandronate sodium raw materials. Summary of the invention

[0005] The invention provides a gas chromatography method for determining amine impurities in ibandronate sodium, which solves the problems in the related art of detecting amine impurities in ibandronate sodium, namely, single amine impurity detection, poor system applicability and low sensitivity.

[0006] The technical solution of the present invention is as follows: The present invention provides a gas chromatography method for determining amine impurities in ibandronate sodium, and adopts the gas chromatography method to detect the residual amine impurities in ibandronate sodium; The amine impurities include 3-methylaminopropionitrile, intermediate I, N,N-dipentylmethylamine, and intermediate I is 3-(N-methyl-N-n-pentylamino)propionitrile.

[0007] As a further technical solution, the gas chromatography is a direct injection gas chromatography.

[0008] As a further technical solution, the injection port temperature during gas chromatography detection is 220°C, the detector temperature is 250°C, 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 adopts a gradient temperature increase: the starting temperature is 115-125°C, maintained for 5 minutes, and then increased to 220°C at a rate of 38-42°C / min, and maintained for 10 minutes.

[0009] As a further technical solution, the chromatographic column used in the gas chromatography detection is a DB-624 chromatographic column or a CP-Volamine chromatographic column.

[0010] As a further technical solution, the chromatographic column is a CP-Volamine chromatographic column.

[0011] In the present invention, a capillary column specially used for amine compounds is selected as a gas chromatographic column, on which a sharper peak shape can be obtained, thus solving the problem of poor repeatability on a common chromatographic column.

[0012] As a further technical solution, the preparation of the test solution during gas chromatography detection adopts an alkali extraction method; In the present invention, since the solvent to be tested has a high boiling point and is alkaline, the salt formed with ibandronate sodium cannot volatilize and is detected by headspace gas chromatography. After extraction, the residual substance can be extracted into an organic solvent, the interference of the acidic main component and other by-products can be eliminated, and the recovery rate of the residual solvent and the recovery rate of the extraction can be improved.

[0013] The alkali extraction method comprises the following steps: mixing ibandronate sodium, alkali solution and an organic solvent, and after layering, taking the organic solvent layer as the test solution.

[0014] As a further technical solution, the alkali solution includes one of a sodium bicarbonate solution, a sodium carbonate solution, and a sodium hydroxide solution; The concentration of the alkali solution is 1-3 mol / L; The organic solvent includes one of dichloromethane, toluene, ethyl acetate and n-hexane.

[0015] As a further technical solution, the alkali solution is a sodium hydroxide solution; The concentration of the alkali solution is 3 mol / L; The organic solvent is dichloromethane.

[0016] As a further technical solution, the mass volume ratio of the ibandronate sodium and the alkali solution is 1g:10~20mL.

[0017] As a further technical solution, the gas chromatography method comprises the following steps: The test solution, reference solution and blank solvent were respectively injected into the gas chromatograph and the chromatogram was recorded; the contents of 3-methylaminopropionitrile, intermediate I and N,N-dipentylmethylamine were calculated by peak area according to the external standard method.

[0018] As a further technical solution, the preparation of the blank solvent comprises the following steps: mixing the alkali solution and the organic solvent, and after layering, taking the organic solvent layer as the blank solvent.

[0019] As a further technical solution, the preparation of the reference solution comprises the following steps: S1. Mix 3-methylaminopropionitrile, intermediate I, N,N-dipentylmethylamine and an organic solvent to obtain a reference substance stock solution; S2. Mix the reference substance stock solution and alkaline solution, separate the layers and take the organic solvent layer as the reference substance solution.

[0020] 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 peak order is 3-methylaminopropionitrile, N, N-dipentylmethylamine, and intermediate I, the theoretical plate number of each peak should be not less than 5000, and the separation degree between each peak should be not less than 1.5; Limit: Calculated by peak area using the external standard method, the starting material, intermediate I and by-product (N,N-dipentylmethylamine) shall not exceed 0.1%.

[0021] In the present invention, when the conditions such as the alkali extraction operation, column flow rate, column temperature, injection port temperature, detector temperature, and gas chromatography column fluctuate within a certain range, the RSD value of the peak area of ​​each analyte is <5.0%; the separation degree of each analyte is >3.0; the number of theoretical plates of each analyte is >5000; the relative deviation of the sample test results under each changed condition and the test results under the original condition is <5.0%. Therefore, when the parameters in the analytical method of the present invention fluctuate within a certain range, the durability meets the requirements.

[0022] The working principle and beneficial effects of the present invention are: In the present invention, gas chromatography is used to detect the amine impurity residues of 3-methylaminopropionitrile, intermediate I, and N,N-dipentylmethylamine in ibandronate sodium. The detection method of the present invention has good specificity. After eliminating the interference of conventional solvents, the separation degree of each analyte is high, and the blank solvent, other materials, impurities, by-products, and sample solutions do not interfere with the determination at the retention time of each material. After methodological verification, the applicability of the optimized system meets the requirements and can achieve the purpose of drug quality control; High detection sensitivity: the detection limits of 3-methylaminopropionitrile, intermediate I, and N, N-dipentylmethylamine are 0.00093%, 0.00089%, and 0.00091%, respectively; when repeated injections are performed, the RSD values ​​of the peak areas of the quantitative limit concentration solutions are all <10%; The detection accuracy is high: From the test results, it can be seen that the average recovery rate of the added samples is in the range of 90% to 105%, and the RSD value of the recovery rate at each concentration level is <5%. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0024] Figure 1 It is the detection chromatogram of the blank solvent of Example 1 of the present invention; Figure 2 The detection chromatogram of the reference substance solution of Example 1 of the present invention; Figure 3 The test chromatogram of the test solution of Example 1 of the present invention; Figure 4 It is a linearity and range test result diagram of 3-methylaminopropionitrile of Example 1 of the present invention; Figure 5 This is a graph showing the linearity and range test results of N,N-dipentylmethylamine in Example 1 of the present invention; Figure 6 This is a graph showing the linearity and range test results of Intermediate I of Example 1 of the present invention. DETAILED DESCRIPTION

[0025] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In the following examples, ibandronate sodium, raw material drug, batch number 230802, source: homemade; Intermediate Ⅰ is 3-(N-methyl-N-n-pentylamino)propionitrile, batch number, 230301, content 99.67%, source: homemade; 3-Methylaminopropionitrile, batch number G2228362, content 98.975%, source: Shanghai Aladdin Biochemical Technology Co., Ltd.; N, N-dipentylmethylamine, batch number 230904, content 99.745%, source: homemade; The model of the gas chromatograph is 7820A.

[0027] Example 1 Determination of the Residues of Starting Materials and Intermediates in Ibandronate Sodium by Gas Chromatography Chromatographic conditions Chromatographic column: capillary column for analysis of amine compounds (Agilent CP-Volamine, 30m×0.32mm); Heating program: the initial temperature is 120°C, maintained for 5 min, then increased to 220°C at a rate of 40°C per minute, maintained for 10 min; Inlet temperature: 220°C; Detector temperature: 250°C; The split ratio is 10:1; Column flow rate: 1.5 mL / min; Injection volume: 1 μL; Hydrogen: 40mL / min; Air: 400mL / min; Tail blowing: 20mL / min; 3 mol / L sodium hydroxide solution: Take 12 g of sodium hydroxide, place it in a 100 mL bottle, dissolve it in water and dilute to the scale, and shake well.

[0028] Blank solvent: Take 5 mL of 3 mol / L sodium hydroxide solution and place it in a stoppered test tube. Accurately add 10 mL of dichloromethane, shake well, let stand to separate the layers, and take the dichloromethane layer.

[0029] Test solution: Take about 0.5 g of the product, weigh it accurately, put 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 it stand to separate the layers, and take the dichloromethane layer.

[0030] Reference substance stock solution: Accurately weigh 25 mg each of 3-methylaminopropionitrile, intermediate I, and N,N-dipentylmethylamine, place in the same 50 mL volumetric flask, dissolve and dilute to the scale with dichloromethane, shake well, accurately measure 5 mL, place in a 50 mL volumetric flask, dilute to the scale with dichloromethane, and shake well.

[0031] Reference substance solution: Take 5 mL of 3 mol / L sodium hydroxide solution and place it in a stoppered test tube. Accurately add 10 mL of reference substance stock solution, shake well, let stand to allow layers to separate, and take the dichloromethane layer.

[0032] Determination: Accurately measure blank solvent, test solution and reference solution, inject them into gas chromatograph respectively, and record the chromatogram.

[0033] System suitability requirements: In the solution chromatogram, the order of peaks is 3-methylaminopropionitrile, N,N-dipentylmethylamine, and intermediate I. The theoretical plate number of each peak should be no less than 5000, and the separation degree between peaks should be no less than 1.5.

[0034] Limit: Calculated by peak area using the external standard method, the concentrations of 3-methylaminopropionitrile, intermediate Ⅰ and N,N-dipentylmethylamine shall not exceed 0.1%.

[0035] Calculation formula:

[0036] Where W 对 : The sample weight of 3-methylaminopropionitrile, intermediate Ⅰ and N, N-dipentylmethylamine reference substance, mg; P: Purity of 3-methylaminopropionitrile, intermediate Ⅰ and N,N-dipentylmethylamine reference substance.

[0037] A 对 : Peak areas of 3-methylaminopropionitrile, intermediate Ⅰ and N, N-dipentylmethylamine in the reference solution; V 对 : Dilution multiple of reference solution; A 样 : Peak areas of 3-methylaminopropionitrile, intermediate Ⅰ and N, N-dipentylmethylamine in the test solution; W 样 : The weight of the test sample, mg; V 样 : Dilution multiple of the test solution.

[0038] Test results: The chromatograms obtained by testing the blank solvent, test solution and reference solution are as follows Figures 1 to 3 shown.

[0039] The contents of 3-methylaminopropionitrile, intermediate I and N,N-dipentylmethylamine were calculated by peak area according to the external standard method, and the results were: none of them were detected, that is, the contents of 3-methylaminopropionitrile, intermediate I and N,N-dipentylmethylamine were less than 0.00093%, 0.0089% and 0.00091%, respectively.

[0040] Experimental Example 1: Verification of the test method 1.1. Specificity test 3 mol / L sodium hydroxide solution: Take 36 g of sodium hydroxide, add 300 mL of water to dissolve, and shake well.

[0041] Blank solvent: Take 5 mL of 3 mol / L sodium hydroxide solution and place it in a stoppered test tube. Accurately add 10 mL of dichloromethane, shake well, let stand to separate the layers, and take the dichloromethane layer.

[0042] N, N-dipentylmethylamine reference substance stock solution: accurately weigh 25 mg of N, N-dipentylmethylamine, place in a 50 mL volumetric flask, dilute to the mark with dichloromethane, and shake well; 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; 3-Methylaminopropionitrile reference stock solution: Accurately weigh 25 mg of 3-methylaminopropionitrile, place in a 50 mL volumetric flask, dilute to the mark with dichloromethane, and shake well; 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; Intermediate I reference substance stock solution: accurately weigh 25 mg of intermediate I, place in a 50 mL volumetric flask, dilute to the mark with dichloromethane, and shake well; Intermediate I positioning solution: accurately measure 1 mL of intermediate I stock solution reference substance, place it in a 10 mL volumetric flask, dilute to the mark with dichloromethane, and shake well; Other positioning solutions: Accurately weigh 25 mg of methanol, ethanol, acetone, N,N-dimethylformamide, benzene, toluene, 1-bromopentane, trimethyl phosphate, dimethyl phosphite, dimethylaminopropionitrile, and 3-aminopropionitrile, respectively, place them in 25 mL volumetric flasks, dilute to the scale with dichloromethane, shake well, and use as stock solutions; accurately measure 1 mL, place it in a 10 mL volumetric flask, dilute to the scale with dichloromethane, and shake well.

[0043] Mixed reference substance 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 scale with dichloromethane, and shake well.

[0044] Reference substance solution: accurately measure 5 mL of 3 mol / L sodium hydroxide solution, place in a stoppered test tube, accurately add 10 mL of the mixed reference substance stock solution, shake well, let stand to allow layers to separate, and take the dichloromethane layer.

[0045] Test solution: Take about 0.5 g of the product, weigh it accurately, put 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 it stand to separate the layers, and take the dichloromethane layer.

[0046] The samples were injected and analyzed according to the chromatographic conditions in the specific implementation mode, and the results are recorded in the following Table 1.

[0047] Table 1 Specificity test results

[0048] 1.2 Limit of Quantitation and Limit of Detection Blank solvent: Take 5 mL of 3 mol / L sodium hydroxide solution and place it in a stoppered test tube. Accurately add 10 mL of dichloromethane, shake well, let stand to separate the layers, and take the dichloromethane layer.

[0049] Quantitation limit stock 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 in a 200 mL volumetric flask, dilute to the mark with dichloromethane, shake well, and use as stock solution; take 2.5 mL of stock solution, place in a 50 mL volumetric flask, dilute to the mark with dichloromethane, and shake well; accurately measure 30 mL, place in a 50 mL volumetric flask, dilute to the mark with dichloromethane, and shake well.

[0050] Quantitative limit solution: accurately measure 5 mL of 3 mol / L sodium hydroxide solution, place in a stoppered test tube, accurately add 10 mL of quantitative limit stock solution, shake well, let stand to separate, take the dichloromethane layer. Make S / N about 10-20, prepare 6 copies in parallel.

[0051] Detection limit stock solution: Accurately measure 6 mL of quantitation limit stock solution, place it in a 20 mL volumetric flask, dilute to the scale with dichloromethane, and shake well.

[0052] Detection limit solution: accurately measure 5 mL of 3 mol / L sodium hydroxide solution, place in a stoppered test tube, accurately add 10 mL of the detection limit stock solution, shake well, let stand to separate, take the dichloromethane layer. Make S / N about 3-10, prepare 3 times in parallel.

[0053] The quantitative limit solution and the detection limit solution were sampled and analyzed according to the chromatographic conditions in the specific implementation method. The results are recorded in Table 2 below.

[0054] Table 2 Results of limit of quantitation and limit of detection tests

[0055] 1.3 Solution stability test Blank solvent: preparation method is the same as that of specificity test; Spiked test solution: Take about 0.5 g of the product, weigh accurately, put 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 mixed reference stock solution (preparation method is the same as that of the specificity test), shake well, let it stand to separate the layers, and take the dichloromethane layer.

[0056] Reference solution: The preparation method is the same as that of the specificity test.

[0057] The reference solution and the test solution were taken and injected once at different time intervals, respectively. The injection and analysis were performed according to the chromatographic conditions in the specific implementation method. The results are recorded in Table 3 below.

[0058] Table 3 Solution stability test results

[0059] 1.4 Linearity and range Take each impurity reference substance separately, add dichloromethane to dissolve and gradually dilute to prepare a series of reference substance mixed solutions with concentrations of 5%, 20%, 50%, 100%, 150%, and 200% of the quantitative limit concentration, respectively, and perform sampling analysis according to the chromatographic conditions in the specific implementation method, with concentration as the abscissa and peak area as the ordinate, perform linear regression, list the regression equation, and report the correlation coefficient, the percentage of the Y-axis intercept to 100% response value, and the response factor RSD. The results are recorded in Tables 4 to 6 and Figures 4 to 6 The results show that this method has good linearity.

[0060] Table 4 3-Methylaminopropionitrile linearity and range test results

[0061] Table 5 N, N-dipentylmethylamine linearity and range test results

[0062] Table 6 Intermediate I linearity and range test results

[0063] 1.5. Repeatability test Blank solvent: Take 5 mL of 3 mol / L sodium hydroxide solution and place it in a stoppered test tube. Accurately add 10 mL of dichloromethane, shake well, let stand to separate the layers, and take the dichloromethane layer.

[0064] Reference substance 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 mixed reference substance stock solution (preparation method is the same as that of the specificity test), shake well, let stand to allow layers to separate, and take the dichloromethane layer.

[0065] Test solution: Take about 0.5g of the product, weigh accurately, place in a stoppered test tube, add 5mL of 3mol / L sodium hydroxide solution to dissolve, accurately add 10mL of dichloromethane, shake well, let stand to separate, and take the dichloromethane layer. Prepare 2 portions in parallel.

[0066] Spiked test solution: accurately measure 20 mL of N, N-dipentylmethylamine reference stock solution, 3-methylaminopropionitrile reference stock solution, and intermediate I reference stock solution, place in a 200 mL volumetric flask, add dichloromethane to dilute to the mark, shake well, and use as the stock solution; take about 0.5 g of this product, accurately weigh, place in a stoppered test tube, add 5 mL of 3 mol / L sodium hydroxide solution to dissolve, accurately add 10 mL of the stock solution, shake well, let stand to separate, take the dichloromethane layer, and prepare 6 copies in parallel; The sample was injected and analyzed according to the chromatographic conditions in the specific implementation method, the chromatogram was recorded, and the content, recovery rate and RSD value of each component peak were calculated by external standard method. The results are recorded in Table 7 below.

[0067] Table 7 Repeatability test results

[0068] 1.6 Accuracy test Blank solvent: Take 5 mL of 3 mol / L sodium hydroxide solution and place it in a stoppered test tube. Accurately add 10 mL of dichloromethane, shake well, let stand to separate the layers, and take the dichloromethane layer.

[0069] 50% reference stock solution: same as linear-50% stock solution.

[0070] 100% reference stock solution: Synlinear - 100% stock solution.

[0071] 150% reference stock solution: Synlinear - 150% stock solution.

[0072] Reference solution: The preparation method is the same as that of the repeatability test.

[0073] 50% spiked test solution: Take about 0.5g of the product, weigh accurately, place in a stoppered test tube, add 5mL of 3mol / L sodium hydroxide solution to dissolve, accurately add 10mL of 50% reference stock solution, shake well, let stand to separate, and take the dichloromethane layer. Prepare 3 copies in parallel.

[0074] 100% spiked test solution: Take about 0.5g of the product, weigh accurately, place in a stoppered test tube, add 5mL of 3mol / L sodium hydroxide solution to dissolve, accurately add 10mL of 100% reference substance stock solution, shake well, let stand to separate, and take the dichloromethane layer. Prepare 3 copies in parallel.

[0075] 150% spiked test solution: Take about 0.5g of the product, weigh accurately, place in a stoppered test tube, add 5mL of 3mol / L sodium hydroxide solution to dissolve, accurately add 10mL of 150% reference stock solution, shake well, let stand to separate, and take the dichloromethane layer. Prepare 3 copies in parallel.

[0076] The samples were injected and analyzed according to the chromatographic conditions in the specific implementation method, the chromatogram was recorded, and the content, recovery rate and RSD value of each impurity were calculated by the external standard method. The results are recorded in the following Tables 8-9.

[0077] Table 8 Accuracy test results

[0078] Table 9 Accuracy test results

[0079] 1.7 Intermediate precision test The same batch of test products was taken and different analysts used different equipment on different dates to conduct experiments according to the requirements of the repeatability test. The RSD of the 12 results determined by the two researchers was calculated and recorded in Table 10 below.

[0080] Table 10 Intermediate precision test results

[0081] 1.8 Durability test The robust chromatographic conditions are shown in Table 11 below.

[0082] Table 11 Durability Chromatographic Conditions

[0083] Solution preparation Blank solvent: Take 5 mL of 3 mol / L sodium hydroxide solution and place it in a stoppered test tube. Accurately add 10 mL of dichloromethane, shake well, let stand to separate the layers, and take the dichloromethane layer.

[0084] Stock solution of reference substance: Take about 25 mg each of N,N-dipentylmethylamine reference substance, 3-methylaminopropionitrile reference substance and intermediate I reference substance, place them in the same 50 mL volumetric flask, dissolve and dilute to the scale with dichloromethane, shake well, accurately measure 5 mL, place it in a 50 mL volumetric flask, dilute to the scale with dichloromethane, and shake well.

[0085] Reference substance 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 reference substance stock solution, shake well, let stand to allow layers to separate, and take the dichloromethane layer.

[0086] Spiked test solution: Take about 0.5 g of the product, weigh accurately, put 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 it stand to separate the layers, and take the dichloromethane layer.

[0087] Measurement and results The samples were injected and analyzed according to the chromatographic conditions in the specific implementation manner, and the chromatogram was recorded. The results are recorded and shown in Table 12.

[0088] Table 12 Durability test results

[0089] 1.9. Verification results evaluation and conclusion The validation results showed that this method had good validation specificity, good linearity, good precision, high accuracy, stable solution and good durability. The results showed that this method was suitable for the determination of 3-methylaminopropionitrile, intermediate Ⅰ and N,N-dipentylmethylamine in ibandronate sodium.

[0090] Experimental Example 2 The chromatographic column (CP-Volamine, 30m×0.32mm) was replaced with a chromatographic column (DB-624, 30m×0.25mm×1.4μm); the other chromatographic conditions were the same as those in Example 1, and 3-methylaminopropionitrile, intermediate I, and N,N-dipentylmethylamine in the sample were detected; The results are shown in Table 13 below: Since the test substance is alkaline, a DB-624 chromatographic column was used, which resulted in very poor reproducibility, unstable recovery, and an RSD greater than 5%.

[0091] Table 13 Experimental results

[0092] Embodiment 2-4 The difference between Examples 2 to 4 and Example 1 is only the type of organic solvent, as shown in Table 14; Stock solution of reference substance: 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 2 mL of each in dichloromethane, toluene, ethyl acetate, and n-hexane, dilute to the scale, and shake well. Accurately measure 2 mL of each in a 20 mL volumetric flask, dilute to the scale with dichloromethane, toluene, ethyl acetate, and n-hexane, and shake well.

[0093] Reference solution: Take 5 mL of 3 mol / L sodium hydroxide solution and place it in stoppered test tubes. Add 10 mL of reference stock solution prepared with each organic solvent. Shake well and let stand to separate the layers. Take the organic layer for sampling and testing. The recovery rate is calculated using dichloromethane organic solvent as the reference. The results are shown in Table 14 below.

[0094] Table 14 Effect of different organic solvents on recovery rate

[0095] It can be seen that when ethyl acetate and n-hexane are organic solvents, the recoveries of 3-methylaminopropionitrile, intermediate I, and N,N-dipentylmethylamine are all low, and toluene interferes with 3-methylaminopropionitrile, so dichloromethane is the most suitable organic solvent.

[0096] Embodiment 5-6 The difference between Examples 5 and 6 and Example 1 is only the type of alkali solution, as shown in Table 15: Reference solution: Accurately weigh 12.5 mg each of 3-methylaminopropionitrile, intermediate Ⅰ, and N,N-dipentylmethylamine, place in the same 25 mL volumetric flask, dissolve and dilute to the scale with dichloromethane, shake well, accurately measure 5 mL, place in a 50 mL volumetric flask, dilute to the scale with dichloromethane, and shake well.

[0097] Spiked test solution: Take about 0.5g of the product, weigh accurately, and place in a stoppered test tube. Add 5mL of saturated sodium bicarbonate, 3mol / L sodium carbonate, and 3mol / L sodium hydroxide solution respectively to dissolve, accurately add 10mL of reference solution, shake well, stand to separate, and take the organic layer for sampling. The results are shown in Table 15 below.

[0098] Table 15 Effect of alkali type on recovery rate

[0099] It can be seen that the use of sodium hydroxide to prepare the alkali solution is more conducive to the recovery of 3-methylaminopropionitrile, intermediate I, and N,N-dipentylmethylamine.

[0100] Embodiment 7-8 The difference between Examples 7 and 8 and Example 1 is only that the concentration of sodium hydroxide solution is different, as shown in Table 16: Reference solution: Accurately weigh 12.5 mg each of 3-methylaminopropionitrile, intermediate Ⅰ, and N,N-dipentylmethylamine, place in the same 25 mL volumetric flask, dissolve and dilute to the scale with dichloromethane, shake well, accurately measure 5 mL, place in a 50 mL volumetric flask, dilute to the scale with dichloromethane, and shake well.

[0101] Spiked test solution: Take about 0.5 g of the product, weigh accurately, and place in stoppered test tubes. Add 5 mL of water, 1 mol / L, 2 mol / L, and 3 mol / L sodium hydroxide solution respectively to dissolve, accurately add 10 mL of the reference solution, shake well, let stand to separate, take the organic layer for sampling, and the results are shown in Table 16 below.

[0102] Table 16 Effect of different alkali solution concentrations on recovery rate

[0103] It can be seen that when the concentration of sodium hydroxide solution reaches 3 mol / L, the recovery rates of 3-methylaminopropionitrile, intermediate Ⅰ and N,N-dipentylmethylamine are optimal.

[0104] The above are only 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 in the protection scope of the present invention.

Claims

1. A gas chromatography method for determining amine impurities in ibandronate sodium, characterized in that: Gas chromatography was used to detect the residual amine impurities in ibandronate sodium; The amine impurities include 3-methylaminopropionitrile, intermediate I, and N,N-dipentylmethylamine; The intermediate I is 3-(N-methyl-N-n-pentylamino)propionitrile.

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

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

4. A gas chromatography method for determining amine impurities in ibandronate sodium according to claim 1, characterized in that: The chromatographic column used in the gas chromatography detection is a DB-624 chromatographic column or a CP-Volamine chromatographic column.

5. A gas chromatography method for determining amine impurities in ibandronate sodium according to claim 1, characterized in that: The preparation of the test solution during the gas chromatography detection adopts the alkaline extraction method; The alkali extraction method comprises the following steps: mixing ibandronate sodium, alkali solution and an organic solvent, and after layering, taking the organic solvent layer as the test solution.

6. A gas chromatography method for determining amine impurities in ibandronate sodium according to claim 5, characterized in that: The alkali solution includes one of sodium bicarbonate solution, sodium carbonate solution and sodium hydroxide solution; The concentration of the alkali solution is 1-3 mol / L; The organic solvent includes one of dichloromethane, toluene, ethyl acetate and n-hexane.

7. A gas chromatography method for determining amine impurities in ibandronate sodium according to claim 5, characterized in that: The mass volume ratio of the ibandronate sodium and the alkali solution is 1g:10-20mL.

8. A gas chromatography method for determining amine impurities in ibandronate sodium according to claim 6, characterized in that: The following steps are involved: The test solution, reference solution and blank solvent were respectively injected into the gas chromatograph and the chromatogram was recorded; the contents of 3-methylaminopropionitrile, intermediate I and N,N-dipentylmethylamine were calculated by peak area according to the external standard method.

9. A gas chromatography method for determining amine impurities in ibandronate sodium according to claim 8, characterized in that: The preparation of the blank solvent comprises the following steps: mixing an alkali solution and an organic solvent, and separating the layers and taking the organic solvent layer as the blank solvent.

10. A gas chromatography method for determining amine impurities in ibandronate sodium according to claim 8, characterized in that: The preparation of the reference solution comprises the following steps: S1. Mix 3-methylaminopropionitrile, intermediate I, N,N-dipentylmethylamine and an organic solvent to obtain a reference substance stock solution; S2. Mix the reference substance stock solution and alkaline solution, separate the layers and take the organic solvent layer as the reference substance solution.

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