Method for determining multiple residual solvents in litamilast raw material by headspace-gas chromatography

Abstract

The invention relates to the field of analytical chemistry, and particularly discloses a method for determining residual solvents N, N-dimethylformamide, dichloromethane, isopropanol, ethyl acetate, methyl tert-butyl ether, ethanol, acetone, tetrahydrofuran and ethylene glycol dimethyl ether in a litamilast raw material by adopting a headspace-gas chromatography method, and a method for determining residual solvents N, N-dimethylformamide, dichloromethane, isopropanol, ethyl acetate, methyl tert-butyl ether, ethanol, acetone, tetrahydrofuran and ethylene glycol dimethyl ether in a litamilast raw material by adopting a headspace-gas chromatography method. The method comprises the following steps of: detecting by using a capillary column with 6 percent of cyanopropyl phenyl-94 percent of dimethyl polysiloxane as a stationary liquid through headspace sample introduction gas chromatography and a flame ionization detector (FID). According to the method disclosed by the invention, nine residual solvents contained in the litamilast raw material can be completely separated in one system, the separation degree is greater than 1.5, the specificity is good, interference from blank solvents and other unknown impurities is avoided, the sensitivity is high, the detection accuracy is high, and the quality of litamilast can be effectively controlled.

Description

Technical Field

[0001] This invention relates to the field of analytical technology, and more specifically to a method for determining multiple residual solvents in ristatin raw materials using headspace gas chromatography. Background Technology

[0002] Rittalact is a novel small-molecule integrin antagonist that inhibits T-cell-mediated inflammation by blocking the binding of two important cell surface proteins (lymphocyte function-associated antigen 1 (LFA-1) and intercellular adhesion molecule 1 (ICAM-1)), thereby reducing the overall inflammatory response. It primarily relieves dry eye symptoms by suppressing inflammation and improving ocular surface moisture.

[0003] Currently, commonly used methods for detecting residual solvents include gas chromatography and loss on drying. However, loss on drying has poor specificity, cannot accurately reflect solvent properties, and has low accuracy. Gas chromatography is more commonly used for detecting residual solvents, but the sensitivity of direct gas injection is insufficient for detecting low concentrations of residual solvents.

[0004] Currently, there are no patent reports on methods for detecting multiple residual solvents in ristatin raw materials. In view of this, the applicant hereby proposes this invention. Summary of the Invention

[0005] This invention provides a headspace gas chromatography method for determining multiple residual solvents in ristatin raw materials. It is not affected by blank solvents and other unknown impurities, and the resolution between each residual solvent is greater than 1.5. The method is simple, rapid and highly accurate.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows:

[0007] Chromatographic column: Capillary column with a length greater than 30m and stationary phase of 6% cyanopropylphenyl-94% dimethylpolysiloxane; Temperature program: Initial column temperature 38–42℃, hold for 5 minutes, then increase to 220℃ at a rate of 10℃ / min, hold for 5 minutes; Injector temperature: 200–300℃; Carrier gas: Nitrogen; Split ratio: 5:1; Flow rate: 1.0–2.2 ml / min; Detector: FID, temperature 200–300℃; Headspace conditions: Headspace vial equilibration temperature 110℃, quantitative loop temperature 110℃, transfer line temperature 120℃, headspace equilibration time 30 minutes; Air flow rate: 400 ml / min; Hydrogen flow rate: 30 ml / min; Make-up nitrogen flow rate: 25 ml / min.

[0008] In the aforementioned technical solution, preferably, the chromatographic column length is 60m. During the research process, the commonly used 30m chromatographic column caused bulging of the acetone peak in the test solution and the resolution did not meet the requirements; the researchers accidentally discovered that using a 60m chromatographic column improved the peak shape of the acetone component and increased the resolution, thus meeting the research requirements.

[0009] Preferably, the chromatographic column is an Agilent DB-624 or an InertCap-624.

[0010] Preferably, the initial column temperature is 38–42°C.

[0011] Preferably, the injection port temperature is 245–255°C.

[0012] Preferably, the detector temperature is 245–255°C.

[0013] In the aforementioned technical solution, residual solvents are quantitatively determined using the external standard method, and the limits for residual solvents are controlled as follows: N,N-dimethylformamide not exceeding 0.088%, dichloromethane not exceeding 0.06%, isopropanol not exceeding 0.5%, ethyl acetate not exceeding 0.5%, methyl tert-butyl ether not exceeding 0.5%, ethanol not exceeding 0.5%, acetone not exceeding 0.5%, tetrahydrofuran not exceeding 0.072%, and ethylene glycol dimethyl ether not exceeding 0.01%.

[0014] During the test, take equal volumes of blank solution, test solution, and reference solution, place them in headspace vials, and introduce them into the gas chromatograph.

[0015] Blank solution: DMSO (dimethyl sulfoxide).

[0016] Test solution: The solvent is DMSO, the solute is listatin. Take an appropriate amount of listatin raw material, add diluent to dissolve it, and prepare a solution with a concentration of 0.2 g / ml as the test solution.

[0017] Reference solution: The solvent is DMSO, and the solute is the residual solvent, which includes N,N-dimethylformamide, dichloromethane, isopropanol, ethyl acetate, methyl tert-butyl ether, ethanol, acetone, tetrahydrofuran, and ethylene glycol dimethyl ether. The concentration of each residual solvent in the reference solution is obtained by multiplying the concentration of the test solution by the residual solvent limit. Specifically: the concentration of N,N-dimethylformamide is 176 μg / ml; the concentration of dichloromethane is 120 μg / ml; the concentration of isopropanol is 1000 μg / ml; the concentration of ethyl acetate is 1000 μg / ml; the concentration of methyl tert-butyl ether is 1000 μg / ml; the concentration of ethanol is 1000 μg / ml; the concentration of acetone is 1000 μg / ml; the concentration of tetrahydrofuran is 144 μg / ml; and the concentration of ethylene glycol dimethyl ether is 20 μg / ml.

[0018] The advantages of this invention are: the method of this invention has high specificity, adopts a capillary column with 6% cyanopropylphenyl-94% dimethyl polysiloxane as the stationary liquid, and performs programmed temperature rise to ensure that each residual solvent can be effectively separated in one chromatographic method, without interference from blank solvent and other unknown impurities. The resolution between each residual solvent is greater than 1.5, reaching more than 2.0. This method has the advantages of being simple, fast, and accurate. The signal-to-noise ratio (S / N) of the quantitation limit for each residual solvent is greater than 30, and the signal-to-noise ratio (S / N) of the detection limit is greater than 3.5. Attached Figure Description

[0019] Figure 1 The gas chromatogram of the blank solution DMSO;

[0020] Figure 2 Gas chromatogram of a mixed reference solution of N,N-dimethylformamide, dichloromethane, isopropanol, ethyl acetate, methyl tert-butyl ether, ethanol, acetone, tetrahydrofuran, and ethylene glycol dimethyl ether.

[0021] Figure 3 The gas chromatogram of the test solution;

[0022] Figure 4 Linear graph of ethanol;

[0023] Figure 5 Linear graph of acetone;

[0024] Figure 6 Linear graph of isopropyl ketone;

[0025] Figure 7 Linear graph of dichloromethane;

[0026] Figure 8 Linearity graph of methyl tert-butyl ether;

[0027] Figure 9 Linearity graph of ethyl acetate;

[0028] Figure 10 Linear graph of tetrahydrofuran;

[0029] Figure 11 Linear graph of ethylene glycol dimethyl ether;

[0030] Figure 12 The graph shows the linearity of N,N-dimethylformamide.

[0031] Specific implementation case methods

[0032] The present invention will be further described below through various embodiments, but these embodiments do not limit the scope of protection of the present invention.

[0033] Example 1: Separation of residual solvents from ristatin raw material

[0034] Chromatographic conditions: Capillary column [DB-624 (60m × 0.32mm × 1.8μm) or equivalent column] with 6% cyanopropylphenyl-94% dimethylpolysiloxane as stationary phase; Temperature program: Initial column temperature 40℃, hold for 5 minutes, increase to 220℃ at a rate of 10℃ / min, hold for 5 minutes; Injector temperature: 250℃; Nitrogen as carrier gas, flow rate 2.0ml / min; Split injection: 5:1; Detector: Flame ionization detector (FID); Detector temperature (FID): 250℃; Air flow rate: 400ml / min; Hydrogen flow rate: 30ml / min; Make-up nitrogen flow rate: 25ml / min; Headspace vial equilibration temperature: 100℃; Quantitative loop temperature: 110℃; Transfer line temperature: 120℃; Headspace equilibration time: 30 minutes; Injection volume: 1ml.

[0035] 1. System suitability test and specificity test

[0036] (1) Solution preparation:

[0037] Blank solution: DMSO (dimethyl sulfoxide)

[0038] Test solution: Weigh 0.2 g of rituximab accurately, place it in a headspace vial, add 1 ml of dimethyl sulfoxide accurately, seal, and use as the test solution.

[0039] N,N-Dimethylformamide reference stock solution: Weigh approximately 1.76 g of N,N-dimethylformamide, place it in a 50 ml volumetric flask, add blank solution to dissolve and dilute to volume, shake well, and use as the N,N-dimethylformamide reference stock solution.

[0040] Dichloromethane reference stock solution: Weigh about 1.2 g of dichloromethane, place it in a 50 ml volumetric flask, add blank solution to dissolve and dilute to volume, shake well, and use as dichloromethane reference stock solution.

[0041] Isopropanol reference stock solution: Weigh about 4.0 g of isopropanol, place it in a 20 ml volumetric flask, add blank solution to dissolve and dilute to volume, shake well, and use as isopropanol reference stock solution.

[0042] Ethyl acetate reference stock solution: Weigh about 4.0 g of ethyl acetate, place it in a 20 ml volumetric flask, add blank solution to dissolve and dilute to volume, shake well, and use as ethyl acetate reference stock solution.

[0043] Methyl tert-butyl ether reference stock solution: Weigh about 4.0 g of methyl tert-butyl ether, place it in a 20 ml volumetric flask, add blank solution to dissolve and dilute to volume, shake well, and use as methyl tert-butyl ether reference stock solution.

[0044] Ethanol reference stock solution: Weigh about 4.0 g of ethanol, place it in a 20 ml volumetric flask, add blank solution to dissolve and dilute to volume, shake well, and use as ethanol reference stock solution.

[0045] Acetone reference stock solution: Weigh about 4.0 g of acetone, place it in a 20 ml volumetric flask, add blank solution to dissolve and dilute to volume, shake well, and use as acetone reference stock solution.

[0046] Tetrahydrofuran reference stock solution: Weigh about 1.44 g of tetrahydrofuran, place it in a 50 ml volumetric flask, add blank solution to dissolve and dilute to volume, shake well, and use as tetrahydrofuran reference stock solution.

[0047] Ethylene glycol dimethyl ether reference stock solution: Weigh about 0.4 g of ethylene glycol dimethyl ether, place it in a 100 ml volumetric flask, add blank solution to dissolve and dilute to volume, shake well, and use as ethylene glycol dimethyl ether reference stock solution.

[0048] Mixed reference stock solution: Accurately measure 1 ml of each of the above reference stock solutions and place them together in a 10 ml volumetric flask. Dilute to the mark with DMSO to obtain the mixed reference stock solution.

[0049] Mixed reference solution: Accurately measure 0.5 ml of the mixed reference stock solution and place it in a 10 ml volumetric flask. Dilute to the mark with DMSO and shake well. Accurately measure 1 ml of the solution and place it in a headspace vial. Seal the vial to obtain the mixed reference solution.

[0050] N,N-Dimethylformamide positioning solution: Accurately measure 0.1 ml of N,N-dimethylformamide reference stock solution and place it in a 10 ml volumetric flask. Dilute to the mark with DMSO and shake well. Accurately measure 1 ml of the solution and place it in a headspace vial. Seal the vial to obtain the N,N-dimethylformamide positioning solution.

[0051] Dichloromethane positioning solution: Accurately measure 0.1 ml of dichloromethane reference stock solution and place it in a 10 ml volumetric flask. Dilute to the mark with DMSO and shake well. Accurately measure 1 ml of the solution and place it in a headspace vial. Seal the vial to obtain the dichloromethane positioning solution.

[0052] Isopropanol positioning solution: Accurately measure 0.1 ml of isopropanol reference stock solution and place it in a 10 ml volumetric flask. Dilute to the mark with DMSO and shake well. Accurately measure 1 ml of the solution and place it in a headspace vial. Seal the vial to obtain the isopropanol positioning solution.

[0053] Ethyl acetate positioning solution: Accurately measure 0.1 ml of ethyl acetate reference stock solution and place it in a 10 ml volumetric flask. Dilute to the mark with DMSO and shake well. Accurately measure 1 ml of the solution and place it in a headspace vial. Seal the vial to obtain the ethyl acetate positioning solution.

[0054] Methyl tert-butyl ether positioning solution: Accurately measure 0.1 ml of methyl tert-butyl ether reference stock solution and place it in a 10 ml volumetric flask. Dilute to the mark with DMSO and shake well. Accurately measure 1 ml of the solution and place it in a headspace vial. Seal the vial to obtain the methyl tert-butyl ether positioning solution.

[0055] Ethanol positioning solution: Accurately measure 0.1 ml of ethanol reference stock solution and place it in a 10 ml volumetric flask. Dilute to the mark with DMSO and shake well. Accurately measure 1 ml of the solution and place it in a headspace vial. Seal the vial to obtain the ethanol positioning solution.

[0056] Acetone positioning solution: Accurately measure 0.1 ml of acetone reference stock solution and place it in a 10 ml volumetric flask. Dilute to the mark with DMSO and shake well. Accurately measure 1 ml of the solution and place it in a headspace vial. Seal the vial to obtain the acetone positioning solution.

[0057] Tetrahydrofuran positioning solution: Accurately measure 0.1 ml of tetrahydrofuran reference stock solution and place it in a 10 ml volumetric flask. Dilute to the mark with DMSO and shake well. Accurately measure 1 ml of the solution and place it in a headspace vial. Seal the vial to obtain the tetrahydrofuran positioning solution.

[0058] Ethylene glycol dimethyl ether positioning solution: Accurately measure 0.1 ml of ethylene glycol dimethyl ether reference stock solution and place it in a 10 ml volumetric flask. Dilute to the mark with DMSO and shake well. Accurately measure 1 ml of the solution and place it in a headspace vial. Seal the vial to obtain the ethylene glycol dimethyl ether positioning solution.

[0059] Separation solution: Weigh 0.2g of rituximab accurately, place it in a headspace, add 1ml of mixed reference solution accurately, seal, and use as separation solution.

[0060] (2) Sample injection: Take 1 ml each of blank solution, mixed reference solution, each positioning solution, resolution solution, and test solution, place them in a headspace vial, and inject them into the gas chromatograph. Inject the same sample of mixed reference solution 5 times and record the chromatograms. Specific experimental results are shown in Tables 4-6 and 6. Figures 1-3 .

[0061] Table 4 Specificity Test Results - 1

[0062]

[0063]

[0064] Table 5 Specificity Test Results - 2

[0065] name Minimum resolution between each analyte and adjacent chromatographic peaks blank solution No interference Mixed reference solution-1 2.3 Separability solution 2.3

[0066] Table 6 Specificity Test Results - 3

[0067]

[0068]

[0069] (3) Experimental results: No interference from blank solution; the resolution between each analyte and adjacent chromatographic peaks is greater than 1.5.

[0070] This method has good system applicability and specificity.

[0071] Examples 2-9

[0072] With the chromatographic conditions unchanged, the following parameters are adjusted:

[0073] (1) Based on Example 1, the flow rates were adjusted to 1.8 ml / min and 2.2 ml / min, respectively;

[0074] (2) Based on Example 1, the chromatographic parameters were adjusted by setting the detector temperature to 245°C and 255°C respectively;

[0075] (3) Based on Example 1, the chromatographic parameters were adjusted by setting the injection port temperature to 245℃ and 255℃ respectively;

[0076] (4) Based on Example 1, the initial column temperature was adjusted to 38℃ and 42℃ respectively;

[0077] Under the chromatographic conditions described above, the mixed reference solution was injected to investigate the minimum resolution between the various residual solvents of ristatin. Specific experimental results are shown in Table 7.

[0078] Table 7. Durability Results of Mixed Control Solution

[0079]

[0080] The experimental results show that the resolution between the residual solvents in the mixed reference solution meets the requirements regardless of the changes in various chromatographic conditions (including initial column temperature, flow rate, detector temperature, and injection port temperature), and the data results indicate that the method has good robustness.

[0081] Example 10: Quantitative analysis of residual solvent in ristatin

[0082] (1) Limit of detection and limit of quantitation

[0083] Limit of Quantification Solution: Accurately weigh appropriate amounts of ethanol, acetone, isopropanol, dichloromethane, methyl tert-butyl ether, ethyl acetate, tetrahydrofuran, ethylene glycol dimethyl ether, and N,N-dimethylformamide into the same volumetric flask. Add DMSO to quantitatively dilute to prepare a mixed solution containing 2.0 μg ethanol, 0.5 μg acetone, 2.5 μg isopropanol, 1.92 μg dichloromethane, 0.2 μg methyl tert-butyl ether, 0.5 μg ethyl acetate, 0.288 μg tetrahydrofuran, 0.64 μg ethylene glycol dimethyl ether, and 8.8 μg N,N-dimethylformamide per 1 ml (i.e., the mixed solution simultaneously contains nine solvents: ethanol, acetone, isopropanol, dichloromethane, methyl tert-butyl ether, ethyl acetate, tetrahydrofuran, ethylene glycol dimethyl ether, and N,N-dimethylformamide). Accurately transfer 1.0 ml of the mixed solution into a 20 ml headspace vial, seal it, and use it as the limit of quantitation solution.

[0084] Limit of Detection Solution: Accurately pipette 2.5 ml of the limit of quantitation solution into a 10 ml volumetric flask, dissolve and dilute to the mark with DMSO, and mix well. Accurately pipette 1.0 ml of this solution into a 20 ml headspace vial, seal, and use as the limit of detection solution.

[0085] According to the Chinese Pharmacopoeia 9101 Analytical Method Validation Guidelines, the limit of quantitation requires a signal-to-noise ratio (S / N) > 10, and the limit of detection requires a signal-to-noise ratio (S / N) > 3. Specific results are shown in Table 8.

[0086] Table 8 Limit of Detection and Limit of Quantification

[0087]

[0088] (2) Linearity and Range

[0089] Take appropriate amounts of ethanol, acetone, isopropanol, dichloromethane, methyl tert-butyl ether, ethyl acetate, tetrahydrofuran, ethylene glycol dimethyl ether, and N,N-dimethylformamide, dissolve and dilute them in DMSO to prepare a series of mixed solutions with gradient concentrations. Accurately measure 1 ml of each solution into a headspace vial and inject it into a gas chromatograph. Plot a standard curve for each component with peak area A as the ordinate and corresponding concentration C as the abscissa, and calculate the linear regression equation. The results are shown in Table 9 and below. Figures 4 to 12 .

[0090] Table 9 Summary of Linear Results

[0091]

[0092]

[0093] Experimental results: Ethanol showed good linearity in the concentration range of 2.008–2022.985 μg / ml, with the linear equation being y = 2.5911x – 34.188, R0. 2The value is 0.9976, and the y-axis intercept deviation is 0.014, which meets the requirements.

[0094] Acetone showed good linearity in the concentration range of 0.501–1998.855 μg / ml, with the linear equation being y = 9.226x – 102.46, R0. 2 The value is 0.9978, and the y-axis intercept deviation is 0.012, which meets the requirements.

[0095] Isopropanol showed good linearity in the concentration range of 2.502–2002.195 μg / ml, with the linear equation being y = 3.0981x – 40.404, R0. 2 The value is 0.9969, and the y-axis intercept deviation is 0.014, which meets the requirements.

[0096] Dichloromethane exhibits good linearity in the concentration range of 1.922–243.320 μg / ml, with the linear equation being y = 2.0624x – 2.4038, R0. 2 The value is 0.9973, and the y-axis intercept deviation is 0.010, which meets the requirements.

[0097] Methyl tert-butyl ether exhibits good linearity in the concentration range of 0.200–1998.530 μg / ml, with the linear equation being y = 26.026x – 305.27, R0. 2 The value is 0.9966, and the y-axis intercept deviation is 0.012, which meets the requirements.

[0098] Ethyl acetate showed good linearity in the concentration range of 0.508–2003.385 μg / ml, with a linear equation of y = 6.9995x – 82.924, R² of 0.9964, and a y-intercept deviation of 0.013, which met the requirements.

[0099] Tetrahydrofuran exhibits good linearity in the concentration range of 0.290–289.040 μg / ml, with the linear equation being y = 12.0128x – 20.5443, R0. 2 The value is 0.9970, and the y-axis intercept deviation is 0.012, which meets the requirements.

[0100] Ethylene glycol dimethyl ether exhibits good linearity in the concentration range of 0.664–40.960 μg / ml, with a linear equation of y = 4.6425x - 0.5481, R² = 0.9960, and a y-intercept deviation of 0.006, which meets the requirements.

[0101] N,N-Dimethylformamide exhibits good linearity in the concentration range of 8.800–355.860 μg / ml, with a linear equation of y = 0.3295x - 0.4505, R² = 0.9938, and y-intercept deviation of 0.008, which meets the requirements.

[0102] (3) Recovery rate of each residual solvent

[0103] Take appropriate amounts of each residual solvent reference standard and add them to the ristatin raw material at 50%–150% of the limit. Calculate the impurity recovery rate by subtracting the amount of residual solvent in the sample from the measured amount and then adding the amount of solvent added. The test results are shown in Tables 15–19.

[0104] Table 15 Results of Residual Solvent Recovery Rate Test

[0105]

[0106]

[0107]

[0108]

[0109]

[0110] Experimental results: The recoveries of ethanol at 50%, 100%, and 150% spiking levels ranged from 104.4% to 115.5%, all within the range of 80% to 120%, with RSDs of 4.03%, 4.34%, and 5.44%, all less than 10%.

[0111] The recoveries of acetone at 50%, 100%, and 150% spiking levels ranged from 99.8% to 110.9%, all within the range of 80% to 120%, with RSDs of 1.80%, 4.78%, and 6.02%, all less than 10%.

[0112] The recoveries of isopropanol at 50%, 100%, and 150% spiking levels ranged from 103.7% to 117.6%, all within the range of 80% to 120%, with RSDs of 3.87%, 5.28%, and 6.56%, all less than 10%.

[0113] The recoveries of dichloromethane spiked at concentrations of 50%, 100%, and 150% ranged from 102.6% to 115.8%, all within the range of 80% to 120%, with RSDs of 1.95%, 5.09%, and 6.31%, all less than 10%.

[0114] The recoveries of methyl tert-butyl ether at 50%, 100%, and 150% concentration levels ranged from 100.2% to 117.8%, all within the range of 80% to 120%, with RSDs of 3.13%, 6.20%, and 8.68%, all less than 10%.

[0115] The recoveries of ethyl acetate at concentrations of 50%, 100%, and 150% ranged from 98.3% to 114.1%, all within the range of 80% to 120%, with RSDs of 2.26%, 6.08%, and 7.76%, all less than 10%.

[0116] The recoveries of tetrahydrofuran spiked at concentrations of 50%, 100%, and 150% ranged from 94.3% to 107.8%, all within the range of 80% to 120%, with RSDs of 2.06%, 5.46%, and 7.00%, all less than 10%.

[0117] The recoveries of ethylene glycol dimethyl ether at 50%, 100%, and 150% concentration levels ranged from 96.3% to 112.3%, all within the range of 80% to 120%, with RSDs of 2.28%, 6.10%, and 7.91%, all less than 10%.

[0118] The recoveries of N,N-dimethylformamide at 50%, 100%, and 150% concentration levels ranged from 92.4% to 112.5%, all within the range of 80% to 120%, with RSDs of 8.53%, 5.70%, and 7.45%, all less than 10%. The recoveries met the requirements.

[0119] Comparative Example 1:

[0120] Based on Example 1, the flow rate was adjusted to 1.0 ml / min, while other chromatographic conditions remained unchanged. The minimum resolution of the mixed reference solution was as follows:

[0121] Table 20 Minimum Resolution of Mixed Standard Solutions

[0122] Flow rate Resolution 0.8 ml / min 0.8 1.0 ml / min 1.6 2.0 ml / min 2.3

[0123] Comparative Example 2:

[0124] Based on Comparative Example 1, the column length was adjusted to 30m, while other chromatographic conditions remained unchanged. The acetone detected in the test solution was as follows:

[0125] Table 21 Minimum resolution and tailing factor of the test sample solution

[0126] Column length Minimum resolution Acetone peak tailing factor 30m 1.2 0.8; There are bulges. 60m 1.6 1.2; Peak

[0127] As shown in the table above, when the column length is 30m, the resolution does not meet the requirements and the peak shape is also poor.

Claims

1. A headspace-gas chromatography method for the detection of multiple residual solvents in ristatin raw material, characterized in that, The following chromatographic conditions are included: Chromatographic column: A capillary column with a length greater than 30m and using 6% cyanopropylphenyl-94% dimethylpolysiloxane as the stationary phase; Temperature rise program: Initial column temperature is 38-42℃, maintained for 5 minutes, then increased to 220℃ at a rate of 10℃ per minute, and maintained for 5 minutes; Inlet temperature: 200~300℃; Carrier gas: nitrogen; Split ratio: 5:1; Flow rate: 1.0–2.2 ml / min; Detector: FID, temperature range: 200–300℃; Headspace conditions: headspace bottle equilibrium temperature 100℃, metering loop temperature 110℃, transfer line temperature 120℃, headspace equilibrium time 30 minutes; Air flow rate: 400 ml / min; hydrogen flow rate: 30 ml / min; tail gas nitrogen flow rate: 25 ml / min.

2. The method according to claim 1, characterized in that, The residual solvents include N,N-dimethylformamide, dichloromethane, isopropanol, ethyl acetate, methyl tert-butyl ether, ethanol, acetone, tetrahydrofuran, and ethylene glycol dimethyl ether.

3. The method according to claim 1, characterized in that, The chromatographic column is 60m long and is either an Agilent DB-624 or an InertCap-624.

4. The method according to claim 1, characterized in that, The initial column temperature is 40℃.

5. The method according to claim 1, characterized in that, The flow rate is 1.8–2.2 ml / min.

6. The method according to claim 1, characterized in that, The injection port temperature is 245–255℃.

7. The method according to claim 1, characterized in that, The detector temperature is 245–255℃.

8. The method according to claim 1, characterized in that, During testing, take equal volumes of the test solution and the reference solution, place them in headspace vials, and introduce them into the gas chromatograph. Test solution: Take an appropriate amount of listatin raw material, add diluent to dissolve it, and use it as the test solution; Reference solutions: Take an appropriate amount of each residual solvent reference standard, add diluent to dissolve, and prepare each reference standard stock solution; take an appropriate amount of each reference standard stock solution, calculate the reference solution concentration of each residual solvent by multiplying the concentration of the test solution by the residual solvent limit, dilute with diluent, and prepare a reference solution.

9. The method according to claim 8, characterized in that, The diluent is DMSO.

10. The method according to claim 8, characterized in that, When quantitatively determining each residual solvent, the external standard method shall be used.

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