Determination of Residual Solvents in LXH-2103 by Headspace Gas Chromatography

Abstract

The present invention belongs to the technical field of drug analysis, and in particular to a method for determining residual solvents in LXH-2103 using headspace gas chromatography. The determination method of the present invention comprises the following steps: preparing a blank solution, a reference solution, and a test solution, injecting the blank solution, the reference solution, and the sample solution into a headspace equilibrium, injecting the blank solution, the reference solution, and the sample solution into a gas chromatograph by headspace injection, recording the chromatogram, and calculating the content by peak area according to the external standard method; the residual solvent is anhydrous methanol, anhydrous ethanol, isopropanol, dichloromethane, or toluene. The method for determining residual solvents in LXH-2103 using headspace gas chromatography provided by the present invention has high sensitivity, good repeatability, high accuracy, and can simultaneously detect multiple residual solvents in LXH-2103, thereby ensuring the quality of LXH-2103 and improving the safety of clinical medication.

Description

Technical Field

[0001] The invention belongs to the technical field of drug analysis, and particularly relates to a method for determining residual solvents in LXH-2103 by utilizing headspace gas chromatography. Background Art

[0002] LXH-2103, chemical name is (±)-3-[(1 RS ,2 RS )-2-[( N , N -dimethylamino)methylene]-1-hydroxycyclohexyl]phenol hydrochloride, molecular formula: C 15 H 23 NO2•HCl, molecular weight: 285.81, its structural formula is: . In the production process of pharmaceutical raw materials and preparations, organic solvents are widely used as synthetic reaction media or extraction agents, which poses a risk. According to the toxicity and potential risks of solvents, they can be divided into four categories. The fourth part of the 2020 edition of the "Chinese Pharmacopoeia" "Determination of Residual Solvents" further clarifies the limit requirements and detection methods for residual solvents in drugs, among which gas chromatography is a commonly used analytical method. For the synthesis process of LXH-2103, it is necessary to focus on controlling the residual amounts of organic solvents such as anhydrous methanol, anhydrous ethanol, isopropanol, dichloromethane and toluene. Specifically, the residual amount of anhydrous methanol should not exceed 0.3%, the residual amount of anhydrous ethanol and isopropanol should not exceed 0.5%, and the residual limits of dichloromethane and toluene are 0.06% and 0.089%, respectively. These limit requirements are intended to ensure the safety of drugs and avoid adverse reactions in patients due to solvent residues.

[0003] Although there are headspace detection methods for detecting different solvents in the prior art, such as the headspace gas chromatography method for detecting the residual amount of organic solvents in glycine API disclosed in CN108614058A, the detection method for residual solvents in nilotinib API disclosed in CN113030323A, the detection method for residual solvents in posaconazole disclosed in CN114184721A, and the method for detecting residual solvents in poly-L-lactic acid and its preparations disclosed in CN114137095A, the above APIs are structurally different from LXH-2103. The molecular structure of LXH-2103 contains cyclohexyl, phenolic hydroxyl, N,N-dimethylaminomethylene, and it is in the form of hydrochloride. Its physical and chemical properties are similar to those of glycine and nilotinib. There are essential differences between lotinib, posaconazole, and poly-L-lactic acid. The phenolic hydroxyl group (-OH) and hydrochloride (Cl⁻) lead to significantly higher polarity of the raw material, which enhances the binding force between the residual solvent and the matrix. Therefore, the headspace detection leads to low solvent release efficiency. The methylene amino group (-CH=N-) and hydrochloride in the molecule are easily decomposed at high temperatures, leading to the degradation of LXH-2103. The molecular weight of LXH-2103 (285.81) is significantly higher than that of glycine (75.07) and poly-L-lactic acid (repeating units of approximately 144). The larger molecular weight and rigid cyclohexyl structure lead to a reduced diffusion rate of the solvent in the matrix. Therefore, many factors lead to unstable results such as poor repeatability and abnormal recovery rate during the residual solvent detection of LXH-2103.

[0004] Quality control methods for LXH-2103 have been reported in the prior art. For example, CN119165099A discloses an HPLC method for simultaneous qualitative and quantitative detection of LXH-2103 and its impurities. This method uses high-performance liquid chromatography to separate and quantify the main components and impurities, but does not yet address specific technical solutions for controlling residual organic solvents. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a method for determining residual solvents in LXH-2103 using headspace gas chromatography, which has high sensitivity, good repeatability and high accuracy, and can simultaneously detect multiple residual solvents in LXH-2103, thereby ensuring the quality of LXH-2103 and improving the safety of clinical use.

[0006] The method for determining residual solvents in LXH-2103 by headspace gas chromatography of the present invention comprises the following steps: preparing a blank solution, a reference solution, and a test solution; injecting the blank solution, the reference solution, and the sample solution into the headspace for 25 to 35 minutes of equilibrium, and then injecting them into a gas chromatograph by headspace injection; recording the chromatogram; and calculating the content by peak area using an external standard method; the residual solvent is anhydrous methanol, anhydrous ethanol, isopropanol, dichloromethane, or toluene;

[0007] The chromatographic conditions include: chromatographic column: a capillary column with cyanopropylphenyl-dimethylpolysiloxane as the stationary liquid;

[0008] Column temperature: start at 38-42°C, maintain for 5-6 minutes, then increase to 150-220°C at a rate of 10-15°C / min, and maintain for 5-8 minutes;

[0009] The headspace conditions include: headspace bottle equilibrium temperature: 80-90°C, equilibrium time: 25-35 minutes; cycle time: 30-35 minutes, quantitative loop temperature: 90-100°C; transmission line temperature: 100-110°C; headspace injection port temperature: 200-220°C.

[0010] The chromatographic conditions also include:

[0011] Detector: FID; Detector temperature: 245-255°C; Carrier gas: Nitrogen; Flow rate: 3.8-4.2 mL / min; Split ratio: 5:1; Hydrogen flow rate: 35-40 mL / min; Air flow rate: 350-400 mL / min. The chromatographic column is DB-624, 30 m x 0.53 mm, with a film thickness of 3 μm.

[0012] The blank solution is an N,N-dimethylformamide solution (with water as solvent) with a volume concentration of 85% to 95%.

[0013] The concentrations of the reference substances anhydrous methanol, anhydrous ethanol, isopropanol, dichloromethane, and toluene in the reference solution are 0.7398 μg / mL to 177.54 μg / mL, 1.259 μg / mL to 302.10 μg / mL, 1.276 μg / mL to 306.12 μg / mL, 0.9405 μg / mL to 37.62 μg / mL, and 0.2135 μg / mL to 51.24 μg / mL, respectively, and the solvent used for dissolution and dilution is a blank solution.

[0014] The concentration of the product LXH-2103 in the test solution is 0.05~0.06g / mL, and the solvent used for dissolution and dilution is a blank solution.

[0015] The detection limits of the method for residual solvents are: 4 ppm for anhydrous methanol, 8 ppm for anhydrous ethanol, 8 ppm for isopropanol, 6 ppm for dichloromethane, and 1 ppm for toluene.

[0016] The quantitative limits of the method for residual solvents are: 15 ppm for anhydrous methanol, 25 ppm for anhydrous ethanol, 26 ppm for isopropanol, 19 ppm for dichloromethane, and 4 ppm for toluene.

[0017] The detection concentration ranges of residual solvents according to the method are as follows: anhydrous methanol concentration is 0.7398 μg / mL to 177.54 μg / mL, anhydrous ethanol concentration is 1.259 μg / mL to 302.10 μg / mL, isopropanol concentration is 1.276 μg / mL to 306.12 μg / mL, dichloromethane concentration is in the range of 0.9405 μg / mL to 37.62 μg / mL, and toluene concentration is 0.2135 μg / mL to 51.24 μg / mL.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] (1) The method of the present invention for determining residual solvents in LXH-2103 using headspace gas chromatography can qualitatively or quantitatively detect the contents of five residual solvents in LXH-2103, namely, anhydrous methanol, anhydrous ethanol, isopropanol, dichloromethane, and toluene.

[0020] (2) The method of the present invention for determining residual solvents in LXH-2103 using headspace gas chromatography, on the one hand, provides a good reference for controlling the residual organic solvents in the production process of LXH-2103, ensuring the quality of LXH-2103, and thus improving the safety of clinical drug use; on the other hand, this method solves the cumbersome problem of using multiple methods to process and detect LXH-2103 when multiple residual solvents are present, greatly improving the convenience of operation and saving labor, time, reagents and other costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is the chromatogram of the blank solution in Example 1;

[0022] Figure 2 is the chromatogram of the reference solution in Example 1;

[0023] Figure 3 is a chromatogram of the sample solution in Example 1;

[0024] Figure 4 This is the chromatogram of the test sample spiked solution in Example 1. DETAILED DESCRIPTION

[0025] The present invention will be further described below with reference to specific embodiments.

[0026] Reagents and other materials used without manufacturer indication are all commercially available conventional products.

[0027] Example 1

[0028] (1) Solution preparation

[0029] (1) Blank solution: Place 5.0 mL of 90% N,N-dimethylformamide in a 20 mL headspace vial and seal.

[0030] (2) Anhydrous methanol solution: Weigh 0.3 g of anhydrous methanol into a 100 mL volumetric flask to which a small amount of 90% N,N-dimethylformamide has been added. Add 90% N,N-dimethylformamide to dilute to the mark and shake well to obtain anhydrous methanol stock solution. 5.0 mL of the anhydrous methanol stock solution is placed into a 100 mL volumetric flask to which a small amount of 90% N,N-dimethylformamide has been added. Add 90% N,N-dimethylformamide to dilute to the mark and shake well. 5.0 mL of this solution is placed into a 20 mL headspace vial and sealed.

[0031] (3) Anhydrous ethanol solution: Weigh 0.5 g of anhydrous ethanol into a 100 mL volumetric flask to which a small amount of 90% N,N-dimethylformamide has been added. Add 90% N,N-dimethylformamide to dilute to the mark and shake well to obtain anhydrous ethanol stock solution. 5.0 mL of the anhydrous ethanol stock solution is placed into a 100 mL volumetric flask to which a small amount of 90% N,N-dimethylformamide has been added. Add 90% N,N-dimethylformamide to dilute to the mark and shake well. 5.0 mL of this solution is placed into a 20 mL headspace vial and sealed.

[0032] (4) Isopropanol solution: Weigh 0.5 g of isopropanol into a 100 mL volumetric flask to which a small amount of 90% N,N-dimethylformamide has been added. Add 90% N,N-dimethylformamide to dilute to the mark and shake well to obtain the isopropanol stock solution. 5.0 mL of the isopropanol stock solution is then placed into a 100 mL volumetric flask to which a small amount of 90% N,N-dimethylformamide has been added. Add 90% N,N-dimethylformamide to dilute to the mark and shake well. 5.0 mL of this solution is then placed into a 20 mL headspace vial and sealed.

[0033] (5) Dichloromethane solution: Weigh 0.06 g of dichloromethane into a 100 mL volumetric flask to which a small amount of 90% N,N-dimethylformamide has been added. Add 90% N,N-dimethylformamide to dilute to the mark and shake well to obtain a dichloromethane stock solution. 5.0 mL of the dichloromethane stock solution is then placed into a 100 mL volumetric flask to which a small amount of 90% N,N-dimethylformamide has been added. Add 90% N,N-dimethylformamide to dilute to the mark and shake well. 5.0 mL of this solution is then placed into a 20 mL headspace vial and sealed.

[0034] (6) Toluene solution: Weigh 0.089 g of toluene into a 100 mL volumetric flask to which a small amount of 90% N,N-dimethylformamide has been added. Add 90% N,N-dimethylformamide to dilute to the mark and shake well to obtain a toluene stock solution. 5.0 mL of the toluene stock solution is then placed into a 100 mL volumetric flask to which a small amount of 90% N,N-dimethylformamide has been added. Add 90% N,N-dimethylformamide to dilute to the mark and shake well. 5.0 mL of this solution is then placed into a 20 mL headspace vial and sealed.

[0035] (7) Reference solution: Weigh 0.3 g of anhydrous methanol, 0.5 g of anhydrous ethanol, 0.5 g of isopropanol, 0.06 g of dichloromethane, and 0.089 g of toluene into a 100 mL volumetric flask to which a small amount of 90% N,N-dimethylformamide has been added. Dilute to the mark with 90% N,N-dimethylformamide and shake to obtain solution A. 5.0 mL of solution A is placed into a 100 mL volumetric flask to which a small amount of 90% N,N-dimethylformamide has been added. Dilute to the mark with 90% N,N-dimethylformamide and shake to obtain the reference solution. 5.0 mL of this solution is placed into a 20 mL headspace vial and sealed.

[0036] (8) Sample solution: Weigh 0.25 g of sample into a 20 mL headspace vial, add 5.0 mL of 90% N,N-dimethylformamide, and seal.

[0037] (9) Test sample spiked solution: Weigh 0.25 g of sample into a 20 mL headspace vial, add 5.0 mL of reference solution, and seal.

[0038] (2) Analysis conditions:

[0039] Instrument: Agilent 7890A headspace gas chromatograph; Chromatographic parameters: Chromatographic column: DB-624 (30 m × 0.53 mm, film thickness 3 μm); Column temperature: Initial temperature: 40°C for 6 min, then increased to 150°C at a rate of 10°C / min and held for 5 min; Carrier gas: Nitrogen; Carrier gas flow rate: 4.0 mL / min; Split ratio: 5:1; Hydrogen flow rate: 40 mL / min; Air flow rate: 400 mL / min; Detector: FID; Detector temperature: 250°C;

[0040] Headspace conditions: headspace inlet temperature: 200°C; headspace bottle equilibrium temperature: 85°C; quantitative loop temperature: 95°C; transfer line temperature: 105°C; equilibrium time: 30 min; cycle time: 30 min.

[0041] (III) Determination: Take the solutions of (1) to (9) and inject them into the headspace for equilibrium. Then inject them into the gas chromatograph and record the chromatogram. Calculate the content by peak area according to the external standard method. The chromatogram of the blank solution is as follows: Figure 1 The chromatogram of the reference solution is shown in Figure 2 The chromatogram of the sample solution is shown in Figure 3 The chromatogram of the spiked solution of the test sample is shown in Figure 4 The measurement results are shown in Table 1.

[0042] Table 1 Retention time of each compound

[0043]

[0044] The blank solution had no significant interference at each target peak; in the spectrum of the reference solution, the separation of each target peak met the requirements; in the spectrum of the sample solution and the mixed solution, there were no significant interfering peaks near the retention time of the target peak; in the spectrum of the mixed solution, the retention time of the target peak was consistent with the retention time of the target peak in the reference solution, and the specificity met the requirements.

[0045] Methodological verification (the chromatographic conditions and headspace conditions used are the same as those in Example 1 unless otherwise specified):

[0046] a. Repeatability

[0047] (1) Reference solution: Weigh 0.3 g of anhydrous methanol, 0.5 g of anhydrous ethanol, 0.5 g of isopropyl alcohol, 0.06 g of dichloromethane, and 0.089 g of toluene into a 100 mL volumetric flask to which a small amount of 90% N,N-dimethylformamide has been added. Dilute to the mark with 90% N,N-dimethylformamide and shake to obtain solution A. 5.0 mL of solution A is placed into a 100 mL volumetric flask to which a small amount of 90% N,N-dimethylformamide has been added. Dilute to the mark with 90% N,N-dimethylformamide and shake to obtain the reference solution. Take six 20 mL headspace vials, add 5.0 mL of the reference solution to each, and seal.

[0048] (2) Blank solution: Place 5.0 mL of 90% N,N-dimethylformamide in a 20 mL headspace vial and seal.

[0049] (3) Repeatability test solution: Weigh 0.25 g of sample into a 20 mL headspace vial, add 5.0 mL of reference solution, and seal. Prepare 6 more vials using the same method.

[0050] The reference solution, blank solution, and repeatability test solution were injected according to the chromatographic conditions and the chromatograms were recorded. The repeatability results are shown in Table 2.

[0051] Table 2 Repeatability results

[0052]

[0053] Under the reference solution item, the RSD of the peak area of anhydrous methanol was 1.4%, the RSD of the peak area of anhydrous ethanol was 1.4%, the RSD of the peak area of isopropanol was 1.4%, the RSD of the peak area of dichloromethane was 0.77%, and the RSD of the peak area of toluene was 0.81, all of which were no more than 10%; under the test solution item, the RSD of the 6 measurement results of anhydrous methanol was 0.90%, the RSD of the 6 measurement results of anhydrous ethanol was 0.98%, the RSD of the 6 measurement results of isopropanol was 1.1%, the RSD of the 6 measurement results of dichloromethane was 1.2%, and the RSD of the 6 measurement results of toluene was 1.2%, all of which were no more than 10%, all meeting the requirements.

[0054] b. Intermediate precision

[0055] The analysts, instruments and chromatographic columns were replaced, and the precision solutions were re-prepared for testing on different dates.

[0056] (1) Reference solution: Weigh 0.3 g of anhydrous methanol, 0.5 g of anhydrous ethanol, 0.5 g of isopropyl alcohol, 0.06 g of dichloromethane, and 0.089 g of toluene into a 100 mL volumetric flask to which a small amount of 90% N,N-dimethylformamide has been added. Dilute to the mark with 90% N,N-dimethylformamide and shake to obtain solution A. 5.0 mL of solution A is placed into a 100 mL volumetric flask to which a small amount of 90% N,N-dimethylformamide has been added. Dilute to the mark with 90% N,N-dimethylformamide and shake to obtain the reference solution. Take six 20 mL headspace vials, add 5.0 mL of the reference solution to each, and seal.

[0057] (2) Blank solution: Place 5.0 mL of 90% N,N-dimethylformamide in a 20 mL headspace vial and seal.

[0058] (3) Intermediate precision test solution: Weigh 0.25 g of sample into a 20 mL headspace vial, add 5.0 mL of reference solution, and seal. Prepare 6 more vials using the same method.

[0059] The reference solution, blank solution, and intermediate precision test solution were injected according to the chromatographic conditions and the chromatograms were recorded. The intermediate precision results are shown in Table 3.

[0060] Table 3 Intermediate precision results

[0061]

[0062] Under the reference solution, the RSD of the peak area of anhydrous methanol was 4.0%, the RSD of the peak area of anhydrous ethanol was 4.5%, the RSD of the peak area of isopropanol was 4.5%, the RSD of the peak area of dichloromethane was 2.5%, and the RSD of the peak area of toluene was 3.5%, all of which were no more than 10%; under the test solution, the RSD of the 6 measurement results of anhydrous methanol was 0.90%, and the RSD of the 12 measurement results of repeatability was 2.0%; the RSD of the 6 measurement results of anhydrous ethanol was 1 .1%, and the RSD of the 12 measurement results together with the repeatability was 2.1%; the RSD of the 6 measurement results of isopropanol was 1.3%, and the RSD of the 12 measurement results together with the repeatability was 2.4%; the RSD of the 6 measurement results of dichloromethane was 1.0%, and the RSD of the 12 measurement results together with the repeatability was 2.4%; the RSD of the 6 measurement results of toluene was 1.4%, and the RSD of the 12 measurement results together with the repeatability was 2.7%; all of them were no more than 10%, which met the requirements.

[0063] c. Limit of detection and limit of quantification

[0064] Blank solution: Weigh anhydrous methanol, anhydrous ethanol, isopropanol, dichloromethane, and toluene and dilute them gradually with 90% N,N-dimethylformamide to obtain the quantification limit and detection limit test solutions. Transfer 5.0 mL to a 20 mL headspace vial and seal. Transfer 5.0 mL of 90% N,N-dimethylformamide to a 20 mL headspace vial and seal to serve as the blank solution.

[0065] Samples were injected under chromatographic conditions, chromatograms were recorded, and the signal-to-noise ratio (S / N) of each target peak was measured. When the S / N ratio was ≥3, the concentration of each solvent converted to the equivalent content in the test sample was defined as the limit of detection. When the S / N ratio was ≥10, the concentration of each solvent converted to the equivalent content in the test sample was defined as the limit of quantification. The results of the detection limit determination are shown in Table 4.

[0066] The calculation formula is: limit of detection LOD (ppm) = minimum detection concentration (µg / mL) × 20;

[0067] Limit of quantification (LOQ) (ppm) = minimum quantitative concentration (µg / mL) × 20.

[0068] Table 4 Results of detection limit and quantification limit determination

[0069]

[0070] The detection limit of anhydrous methanol is 4ppm, the quantification limit is 15ppm, and the RSD of the peak area of the quantification limit is 2.9% for 6 times; the detection limit of anhydrous ethanol is 8ppm, the quantification limit is 25ppm, and the RSD of the peak area of the quantification limit is 9.2% for 6 times; the detection limit of isopropanol is 8ppm, the quantification limit is 26ppm, and the RSD of the peak area of the quantification limit is 3.0% for 6 times; the detection limit of dichloromethane is 6ppm, the quantification limit is 19ppm, and the RSD of the peak area of the quantification limit is 2.6% for 6 times; the detection limit of toluene is 1ppm, the quantification limit is 4ppm, and the RSD of the peak area of the quantification limit is 3.3% for 6 times; the S / N of the detection limit of each target peak is not less than 3, and the S / N of the quantification limit is not less than 10, which meets the requirements.

[0071] d. Linear

[0072] Examine the extent to which peak area is directly proportional to concentration within the design range.

[0073] (1) Blank solution: Place 5.0 mL of 90% N,N-dimethylformamide in a 20 mL headspace vial and seal.

[0074] (2) Anhydrous methanol linear stock solution: Weigh 0.3 g of anhydrous methanol and place it in a 100 mL volumetric flask to which a small amount of 90% N,N-dimethylformamide has been added. Add 90% N,N-dimethylformamide to dilute to the scale and shake well.

[0075] (3) Anhydrous ethanol linear stock solution: Weigh 0.5 g of anhydrous ethanol and place it in a 100 mL volumetric flask to which a small amount of 90% N,N-dimethylformamide has been added. Add 90% N,N-dimethylformamide to dilute to the scale and shake well.

[0076] (4) Isopropanol linear stock solution: Weigh 0.5 g of isopropanol and place it in a 100 mL volumetric flask to which a small amount of 90% N,N-dimethylformamide has been added. Add 90% N,N-dimethylformamide to dilute to the mark and shake well.

[0077] (5) Dichloromethane linear stock solution: Weigh 0.06 g of dichloromethane and place it in a 100 mL volumetric flask to which a small amount of 90% N,N-dimethylformamide has been added. Add 90% N,N-dimethylformamide to dilute to the mark and shake well.

[0078] (6) Toluene linear stock solution: Weigh 0.089 g of toluene and place it in a 100 mL volumetric flask to which a small amount of 90% N,N-dimethylformamide has been added. Add 90% N,N-dimethylformamide to dilute to the mark and shake well.

[0079] (7) Linearity test solution ①: Take an appropriate amount of each linearity stock solution and add 90% N,N-dimethylformamide to dilute it to the quantitative limit concentration.

[0080] (8) Linearity test solution ②: Measure 1.0 mL of each of the linearity stock solutions (2) to (6) and place them in the same 100 mL volumetric flask. Add 90% N,N-dimethylformamide and dilute to the mark.

[0081] (9) Linearity test solution ③: Measure 2.5 mL of each of the linearity stock solutions (2) to (6) and place them in the same 100 mL volumetric flask. Add 90% N,N-dimethylformamide and dilute to the mark.

[0082] (10) Linearity test solution ④: Measure 5.0 mL of each of the linearity stock solutions (2) to (6) and place them in the same 100 mL volumetric flask. Add 90% N,N-dimethylformamide and dilute to the mark.

[0083] (11) Linearity test solution ⑤: Measure 6.0 mL of each of the linearity stock solutions (2) to (6) and place them in the same 100 mL volumetric flask. Add 90% N,N-dimethylformamide and dilute to the mark.

[0084] 5.0 mL of each of the blank solution and linearity test solutions ① through ⑤ were placed in 20 mL headspace vials, sealed, and injected headspace-wise. Chromatograms were recorded. Linear regression was performed using the peak area of each target peak as the ordinate and the concentration (µg / mL) of each solvent in the linearity test solution as the abscissa. The linear equation and correlation coefficient, r, were calculated. The linearity test data are shown in Table 5.

[0085] Table 5 Linearity determination data

[0086]

[0087] The linear equation for anhydrous methanol concentration is in the range of 0.7398μg / mL to 177.54μg / mL, and the correlation coefficient r is 0.9998; the linear equation for anhydrous ethanol concentration is in the range of 1.259μg / mL to 302.10μg / mL, and the correlation coefficient r is 0.9998; the linear equation for isopropyl alcohol concentration is in the range of 1.276μg / mL to 306.12μg / mL, The linear equation is Y=1.3569X-0.7102, and the correlation coefficient r is 0.9998; in the range of dichloromethane concentration from 0.9405μg / mL to 37.62μg / mL, the linear equation is Y=1.6567X-0.1112, and the correlation coefficient r is 0.9998; in the range of toluene concentration from 0.2135μg / mL to 51.24μg / mL, the linear equation is Y=5.5867X-0.0949, and the correlation coefficient r is 0.9997.

[0088] e. Accuracy

[0089] (1) Blank solution: Place 5.0 mL of 90% N,N-dimethylformamide in a 20 mL headspace vial and seal.

[0090] (2) Sample blank solution: Weigh 0.25 g of sample into a 20 mL headspace vial, add 5.0 mL of 90% N,N-dimethylformamide, and seal.

[0091] (3) Reference solution: Weigh 0.3 g of anhydrous methanol, 0.5 g of anhydrous ethanol, 0.5 g of isopropanol, 0.06 g of dichloromethane, and 0.089 g of toluene into a 100 mL volumetric flask to which a small amount of 90% N,N-dimethylformamide has been added. Add 90% N,N-dimethylformamide to dilute to the mark and shake to obtain solution A. Take 5.0 mL of solution A and place it into a 100 mL volumetric flask to which a small amount of 90% N,N-dimethylformamide has been added. Add 90% N,N-dimethylformamide to dilute to the mark and shake to obtain the reference solution. Take six 20 mL headspace vials, add 5.0 mL of the reference solution to each, and seal.

[0092] (4) Accuracy test solution 1: Take an appropriate amount of each linear stock solution under the linearity test item, add 90% N,N-dimethylformamide to dilute to the quantitative limit concentration solution; take three headspace bottles, pre-add 0.25g of sample, and then add 5.0mL of quantitative limit concentration solution to each bottle and seal.

[0093] (5) Accuracy test solution 2: Prepare the stock solution in the same way as the linearity test solution ③ under the linearity test. Take three headspace bottles, add 0.25 g of sample in advance, and then add 5.0 mL of the stock solution to each bottle and seal.

[0094] (6) Accuracy test solution 3: Prepare the stock solution in the same way as the linearity test solution ④ under the linearity test item; take three headspace bottles, add 0.25 g of sample in advance, and then add 5.0 mL of stock solution to each bottle and seal.

[0095] (7) Accuracy test solution 4: Prepare the stock solution in the same manner as the linearity test solution ⑤ under the linearity test item; take three headspace bottles, pre-add 0.25 g of sample, and then add 5.0 mL of stock solution to each bottle and seal.

[0096] Heat the headspace vials containing the reference solution, blank solution, sample blank solution, and accuracy test solution at 85°C for 30 minutes. Inject 1.0 mL of gas headspace solution and record the chromatogram. Accuracy test data for anhydrous methanol, anhydrous ethanol, isopropanol, dichloromethane, and toluene are shown in Tables 6-10.

[0097] Calculation formula:

[0098] Recovery rate (%) = ,

[0099] Where: A 测 is the peak area of the solvent in the test solution spectrum;

[0100] A 空 is the peak area of the solvent in the blank solution spectrum;

[0101] A 样空 is the peak area of the solvent in the sample blank solution spectrum;

[0102] Ā 对 is the average peak area of the solvent in the spectrum of the reference solution;

[0103] C 测 is the concentration of the solvent in the test solution, µg / mL;

[0104] C 对 is the concentration of the solvent in the reference solution, µg / mL;

[0105] W 测 is the weight of LXH-2103 added to the test solution, g;

[0106] W 样空 is the weight of LXH-2103 in the sample blank solution, g.

[0107] Table 6 Anhydrous methanol accuracy test data

[0108]

[0109] Table 7 Anhydrous ethanol accuracy test data

[0110]

[0111] Table 8 Isopropyl alcohol accuracy test data

[0112]

[0113] Table 9 Dichloromethane accuracy test data

[0114]

[0115] Table 10 Toluene accuracy test data

[0116]

[0117] The recovery rate of anhydrous methanol ranged from 97.26% to 114.46%, and the relative standard deviation of the recovery rate was 6.5%; the recovery rate of anhydrous ethanol ranged from 95.38% to 102.93%, and the relative standard deviation of the recovery rate was 2.4%; the recovery rate of isopropanol ranged from 97.81% to 107.18%, and the relative standard deviation of the recovery rate was 2.4%; the recovery rate of dichloromethane ranged from 102.78% to 114.42%, and the relative standard deviation of the recovery rate was 3.1%; the recovery rate of toluene ranged from 102.01% to 118.43%, and the relative standard deviation of the recovery rate was 5.8%; all met the requirements.

[0118] Through the above tests on precision, linearity, and accuracy, it can be determined that the analytical method is applicable and the results obtained are accurate and reliable when the concentration of anhydrous methanol is in the range of 0.7398 μg / mL to 177.54 μg / mL (equivalent to 15 ppm to 3551 ppm of the sample), the concentration of anhydrous ethanol is in the range of 1.259 μg / mL to 302.10 μg / mL (equivalent to 25 ppm to 6042 ppm of the sample), the concentration of isopropanol is in the range of 1.276 μg / mL to 306.12 μg / mL (equivalent to 26 ppm to 6122 ppm of the sample), the concentration of dichloromethane is in the range of 0.9405 μg / mL to 37.62 μg / mL (equivalent to 19 ppm to 752 ppm of the sample), and the concentration of toluene is in the range of 0.2135 μg / mL to 51.24 μg / mL (equivalent to 4 ppm to 1025 ppm of the sample).

[0119] f. Solution stability

[0120] (1) Blank solution: Place 5.0 mL of 90% N,N-dimethylformamide in a 20 mL headspace vial and seal.

[0121] (2) Reference solution: Weigh 0.3 g of anhydrous methanol, 0.5 g of anhydrous ethanol, 0.5 g of isopropanol, 0.06 g of dichloromethane, and 0.089 g of toluene into a 100 mL volumetric flask to which a small amount of 90% N,N-dimethylformamide has been added. Dilute to the mark with 90% N,N-dimethylformamide and shake to obtain solution A. 25.0 mL of solution A is placed into a 500 mL volumetric flask to which a small amount of 90% N,N-dimethylformamide has been added. Dilute to the mark with 90% N,N-dimethylformamide and shake to obtain the reference solution. Take six 20 mL headspace vials, add 5.0 mL of the reference solution to each, and seal.

[0122] (3) Test sample spiked solution: Weigh 0.25 g of sample into a 20 mL headspace vial, add 5.0 mL of reference solution, and seal.

[0123] Between 0 and 120 hours, select appropriate time points to perform the measurements according to the chromatographic conditions and record the chromatograms. The test results for the reference solution and the test solution spiked with the test substance are shown in Tables 11 and 12.

[0124] For the reference solution, the RSD of the peak areas of anhydrous methanol, anhydrous ethanol, isopropanol, dichloromethane, and toluene should not be greater than 10%, and the degree of separation should not be less than 1.5; for the test sample spiked solution, the RSD of the measured values of each residual solvent peak result should not be greater than 10%. It can be considered that the reference solution and the test sample spiked solution are stable under the LXH-2103 residual solvent item.

[0125] Table 11 Test results of reference solution

[0126]

[0127] Table 12 Test results of spiked solution of test sample

[0128]

[0129] Within 0-120 hours of storage, the RSD of the peak area for each chromatographic peak in the reference solution was no greater than 10%, and the resolution of each chromatographic peak was no greater than 1.5. For the test sample spiked solution, the RSDs for anhydrous methanol were 1.3%, anhydrous ethanol was 1.3%, isopropanol was 1.3%, dichloromethane was 1.1%, and toluene was 1.2%. The RSDs for each target peak were all less than 10%. Both the reference solution and the test sample spiked solution were stable for 120 hours.

[0130] Example 2

[0131] (1) Solution preparation

[0132] (1) Blank solution: Place 5.0 mL of 90% N,N-dimethylformamide in a 20 mL headspace vial and seal.

[0133] (2) Reference solution: Weigh 0.3 g of anhydrous methanol, 0.5 g of anhydrous ethanol, 0.5 g of isopropanol, 0.06 g of dichloromethane, and 0.089 g of toluene into a 100 mL volumetric flask to which a small amount of 90% N,N-dimethylformamide has been added. Add 90% N,N-dimethylformamide to dilute to the mark, and shake to obtain solution A. Take 5.0 mL of solution A and place it into a 100 mL volumetric flask to which a small amount of 90% N,N-dimethylformamide has been added. Add 90% N,N-dimethylformamide to dilute to the mark, and shake to obtain the reference solution. Take six 20 mL headspace vials, add 5.0 mL of the reference solution to each, and seal.

[0134] (3) Test sample spiked solution: Weigh 0.25 g of sample into a 20 mL headspace vial, add 5.0 mL of reference solution, and seal.

[0135] (2) Analysis conditions:

[0136] Instrument: Agilent 7890A headspace gas chromatograph, FID detector; chromatographic column: DB-624 (30 m × 0.53 mm, film thickness 3 μm); chromatographic parameters: carrier gas: nitrogen; carrier gas flow rate: 4.2 ml / min; split ratio: 5:1; hydrogen flow rate: 40 mL / min; air flow rate: 400 mL / min; detector temperature: 250°C; column temperature: start at 40°C for 6 min, increase to 150°C at a rate of 10°C / min, and maintain for 5 min.

[0137] Headspace detection parameters: headspace bottle equilibrium temperature: 85°C; quantitative loop temperature: 95°C; transfer line temperature: 105°C; headspace injection port temperature: 200°C; headspace equilibrium time: 30 min; cycle time: 30 min.

[0138] (III) Determination: After the reference solution, blank solution, and test sample spiked solution are equilibrated in the headspace, they are injected into a gas chromatograph and the chromatogram is recorded. The test results of the reference solution are shown in Table 13, and the test sample spiked solution are shown in Table 14.

[0139] Table 13 Test results of reference solution

[0140]

[0141] Table 14 Test results of spiked solution of test sample

[0142]

[0143] In the reference solution, the RSDs of the peak areas of anhydrous methanol, anhydrous ethanol, isopropanol, dichloromethane and toluene were 1.9, 2.3, 1.5, 3.7 and 3.0, respectively, all less than 10%; in the spiked solution of the test sample, the separation between the chromatographic peaks was greater than 1.5, the tailing factor of each chromatographic peak was less than 1.2, and the theoretical plate number of each chromatographic peak was greater than 10,000. The measured values were accurate.

[0144] Example 3

[0145] (1) The solution preparation is the same as in Example 2.

[0146] (2) Analysis conditions:

[0147] Instrument: Agilent 7890A headspace gas chromatograph, FID detector; chromatographic column: DB-624 (30 m × 0.53 mm, film thickness 3 μm); chromatographic parameters: carrier gas: nitrogen; carrier gas flow rate: 3.8 ml / min; split ratio: 5:1; hydrogen flow rate: 35 mL / min; air flow rate: 350 mL / min; detector temperature: 250°C; column temperature: start at 40°C and hold for 6 min, then increase to 150°C at a rate of 10°C / min and hold for 5 min.

[0148] Headspace detection parameters: headspace bottle equilibrium temperature: 85°C; quantitative loop temperature: 95°C; transfer line temperature: 105°C; headspace injection port temperature: 200°C; headspace equilibrium time: 30 min; cycle time: 30 min.

[0149] (III) Determination: After the reference solution, blank solution, and test sample spiked solution are equilibrated in the headspace, they are injected into a gas chromatograph and the chromatogram is recorded. The test results of the reference solution are shown in Table 15, and the test sample spiked solution are shown in Table 16.

[0150] Table 15 Test results of reference solution

[0151]

[0152] Table 16 Test results of spiked solution of test sample

[0153]

[0154] In the reference solution, the RSDs of the peak areas of anhydrous methanol, anhydrous ethanol, isopropanol, dichloromethane and toluene were 2.1, 2.2, 2.0, 1.9 and 1.8, respectively, all less than 10%; in the spiked solution of the test sample, the separation between the chromatographic peaks was greater than 1.5, the tailing factor of each chromatographic peak was less than 1.2, and the theoretical plate number of each chromatographic peak was greater than 10,000. The measured values were accurate.

[0155] Example 4

[0156] (1) Solution preparation is the same as in Example 2. (2) Analysis conditions:

[0157] Instrument: Agilent 7890A headspace gas chromatograph, FID detector; chromatographic column: DB-624 (30 m × 0.53 mm, film thickness 3 μm); chromatographic parameters: carrier gas: nitrogen; carrier gas flow rate: 4.0 ml / min; split ratio: 5:1; hydrogen flow rate: 40 mL / min; air flow rate: 400 mL / min; detector temperature: 250°C; column temperature: start at 42°C for 5 min, increase to 220°C at a rate of 15°C / min, and maintain for 8 min.

[0158] Headspace detection parameters: headspace bottle equilibrium temperature: 85°C; quantitative loop temperature: 95°C; transfer line temperature: 105°C; headspace injection port temperature: 200°C; headspace equilibrium time: 30 min; cycle time: 35 min.

[0159] (III) Determination: After the reference solution, blank solution, and test sample spiked solution are equilibrated in the headspace, they are injected into a gas chromatograph and the chromatogram is recorded. The test results of the reference solution are shown in Table 17, and the test sample spiked solution test results are shown in Table 18.

[0160] Table 17 Test results of reference solution

[0161]

[0162] Table 18 Test results of the spiked solution of the test sample

[0163]

[0164] In the reference solution, the RSDs of the peak areas of anhydrous methanol, anhydrous ethanol, isopropanol, dichloromethane and toluene were 1.9, 1.9, 1.9, 1.4 and 1.3, respectively, all less than 10%; in the spiked solution of the test sample, the separation between the chromatographic peaks was greater than 1.5, the tailing factor of each chromatographic peak was less than 1.2, and the theoretical plate number of each chromatographic peak was greater than 10,000. The measured values were accurate.

[0165] Example 5

[0166] (1) The solution preparation is the same as in Example 2.

[0167] (2) Analysis conditions:

[0168] Instrument: Agilent 7890A headspace gas chromatograph, FID detector; chromatographic column: DB-624 (30 m × 0.53 mm, film thickness 3 μm); chromatographic parameters: carrier gas: nitrogen; carrier gas flow rate: 4.0 ml / min; split ratio: 5:1; hydrogen flow rate: 40 mL / min; air flow rate: 400 mL / min; detector temperature: 250°C; column temperature: start at 38°C for 6 min, increase to 150°C at a rate of 10°C / min, and hold for 5 min.

[0169] Headspace detection parameters: headspace bottle equilibrium temperature: 85°C; quantitative loop temperature: 95°C; transfer line temperature: 105°C; headspace injection port temperature: 200°C; headspace equilibrium time: 30 min; cycle time: 30 min.

[0170] (III) Determination: After the reference solution, blank solution, and test sample spiked solution are equilibrated in the headspace, they are injected into a gas chromatograph and the chromatogram is recorded. The test results of the reference solution are shown in Table 19, and the test sample spiked solution test results are shown in Table 20.

[0171] Table 19 Test results of reference solution

[0172]

[0173] Table 20 Test results of spiked solution of test sample

[0174]

[0175] In the reference solution, the RSDs of the peak areas of anhydrous methanol, anhydrous ethanol, isopropanol, dichloromethane and toluene were 1.4, 1.4, 1.5, 1.0 and 0.9, respectively, all less than 10%; in the spiked solution of the test sample, the separation between the chromatographic peaks was greater than 1.5, the tailing factor of each chromatographic peak was less than 1.2, and the theoretical plate number of each chromatographic peak was greater than 10,000. The measured values were accurate.

[0176] Example 6

[0177] (The solution preparation is the same as in Example 2.

[0178] (2) Analysis conditions:

[0179] Instrument: Agilent 7890A headspace gas chromatograph, FID detector; chromatographic column: DB-624 (30 m × 0.53 mm, film thickness 3 μm); chromatographic parameters: carrier gas: nitrogen; carrier gas flow rate: 4.0 ml / min; split ratio: 5:1; hydrogen flow rate: 40 mL / min; air flow rate: 400 mL / min; detector temperature: 250°C; column temperature: start at 40°C for 6 min, increase to 150°C at a rate of 10°C / min, and maintain for 5 min.

[0180] Headspace detection parameters: headspace bottle equilibrium temperature: 90°C; quantitative loop temperature: 100°C; transfer line temperature: 110°C; headspace injection port temperature: 200°C; headspace equilibrium time: 30 min; cycle time: 30 min.

[0181] (III) Determination: After the reference solution, blank solution, and test sample spiked solution are equilibrated in the headspace, they are injected into a gas chromatograph and the chromatogram is recorded. The test results of the reference solution are shown in Table 21, and the test sample spiked solution are shown in Table 22.

[0182] Table 21 Test results of reference solution

[0183]

[0184] Table 22 Test results of spiked solution of test sample

[0185]

[0186] In the reference solution, the RSDs of the peak areas of anhydrous methanol, anhydrous ethanol, isopropanol, dichloromethane and toluene were 1.8, 2.1, 1.6, 1.2 and 1.2, respectively, all less than 10%; in the spiked solution of the test sample, the separation between the chromatographic peaks was greater than 1.5, the tailing factor of each chromatographic peak was less than 1.2, and the theoretical plate number of each chromatographic peak was greater than 10,000. The measured values were accurate.

[0187] Example 7

[0188] (1) The solution preparation is the same as in Example 2.

[0189] (2) Analysis conditions:

[0190] Instrument: Agilent 7890A headspace gas chromatograph, FID detector; chromatographic column: DB-624 (30 m × 0.53 mm, film thickness 3 μm); chromatographic parameters: carrier gas: nitrogen; carrier gas flow rate: 4.0 ml / min; split ratio: 5:1; hydrogen flow rate: 40 mL / min; air flow rate: 400 mL / min; detector temperature: 250°C; column temperature: start at 40°C for 6 min, increase to 150°C at a rate of 10°C / min, and maintain for 5 min.

[0191] Headspace detection parameters: headspace bottle equilibrium temperature: 80°C; quantitative loop temperature: 90°C; transfer line temperature: 100°C; headspace injection port temperature: 200°C; headspace equilibrium time: 30 min; cycle time: 30 min.

[0192] (III) Determination: After the reference solution, blank solution, and test sample spiked solution are equilibrated in the headspace, they are injected into a gas chromatograph and the chromatogram is recorded. The test results of the reference solution are shown in Table 23, and the test sample spiked solution are shown in Table 24.

[0193] Table 23 Test results of reference solution

[0194]

[0195] Table 24 Test results of spiked solution of test sample

[0196]

[0197] In the reference solution, the RSDs of the peak areas of anhydrous methanol, anhydrous ethanol, isopropanol, dichloromethane and toluene were 1.3, 1.4, 1.2, 1.4 and 1.5, respectively, all less than 10%; in the spiked solution of the test sample, the separation between the chromatographic peaks was greater than 1.5, the tailing factor of each chromatographic peak was less than 1.2, and the theoretical plate number of each chromatographic peak was greater than 10,000. The measured values were accurate.

[0198] Example 8

[0199] (1) The solution preparation is the same as in Example 2.

[0200] (2) Analysis conditions:

[0201] Instrument: Agilent 7890A headspace gas chromatograph, FID detector; chromatographic column: DB-624 (30 m × 0.53 mm, film thickness 3 μm); chromatographic parameters: carrier gas: nitrogen; carrier gas flow rate: 4.0 ml / min; split ratio: 5:1; hydrogen flow rate: 40 mL / min; air flow rate: 400 mL / min; detector temperature: 255°C; column temperature: start at 40°C for 6 min, increase to 150°C at a rate of 10°C / min, and hold for 5 min.

[0202] Headspace detection parameters: headspace bottle equilibrium temperature: 85°C; quantitative loop temperature: 95°C; transfer line temperature: 105°C; headspace injection port temperature: 220°C; headspace equilibrium time: 30 min; cycle time: 30 min.

[0203] (III) Determination: After the reference solution, blank solution, and test sample spiked solution are equilibrated in the headspace, they are injected into a gas chromatograph and the chromatogram is recorded. The test results of the reference solution are shown in Table 25, and the test sample spiked solution are shown in Table 26.

[0204] Table 25 Test results of reference solution

[0205]

[0206] Table 26 Test results of spiked solution of test sample

[0207]

[0208] In the reference solution, the RSDs of the peak areas of anhydrous methanol, anhydrous ethanol, isopropanol, dichloromethane and toluene were 3.6, 2.8, 3.5, 5.2 and 4.4, respectively, all less than 10%; in the spiked solution of the test sample, the separation between the chromatographic peaks was greater than 1.5, the tailing factor of each chromatographic peak was less than 1.2, and the theoretical plate number of each chromatographic peak was greater than 10,000. The measured values were accurate.

[0209] Example 9

[0210] (1) The solution preparation is the same as in Example 2.

[0211] (2) Analysis conditions:

[0212] Instrument: Agilent 7890A headspace gas chromatograph, FID detector; chromatographic column: DB-624 (30 m × 0.53 mm, film thickness 3 μm); chromatographic parameters: carrier gas: nitrogen; carrier gas flow rate: 4.0 ml / min; split ratio: 5:1; hydrogen flow rate: 40 mL / min; air flow rate: 400 mL / min; detector temperature: 245°C; column temperature: start at 40°C for 6 min, increase to 150°C at a rate of 10°C / min, and hold for 5 min.

[0213] Headspace detection parameters: headspace bottle equilibrium temperature: 85°C; quantitative loop temperature: 95°C; transfer line temperature: 105°C; headspace injection port temperature: 200°C; headspace equilibrium time: 30 min; cycle time: 30 min.

[0214] (III) Determination: After the reference solution, blank solution, and test sample spiked solution are equilibrated in the headspace, they are injected into a gas chromatograph and the chromatogram is recorded. The test results of the reference solution are shown in Table 27, and the test sample spiked solution are shown in Table 28.

[0215] Table 27 Test results of reference solution

[0216]

[0217] Table 28 Test results of sample spiked solution

[0218]

[0219] In the reference solution, the RSDs of the peak areas of anhydrous methanol, anhydrous ethanol, isopropanol, dichloromethane and toluene were 1.1, 1.3, 1.2, 1.1 and 1.0, respectively, all less than 10%; in the spiked solution of the test sample, the separation between the chromatographic peaks was greater than 1.5, the tailing factor of each chromatographic peak was less than 1.2, and the theoretical plate number of each chromatographic peak was greater than 10,000. The measured values were accurate.

[0220] Example 10

[0221] (1) The solution preparation is the same as in Example 2.

[0222] (2) Analysis conditions:

[0223] Instrument: Agilent 7890A headspace gas chromatograph, FID detector; chromatographic column: DB-624 (30 m × 0.53 mm, film thickness 3 μm); chromatographic parameters: carrier gas: nitrogen; carrier gas flow rate: 4.0 ml / min; split ratio: 5:1; hydrogen flow rate: 40 mL / min; air flow rate: 400 mL / min; detector temperature: 250°C; column temperature: start at 40°C for 6 min, increase to 150°C at a rate of 10°C / min, and maintain for 5 min.

[0224] Headspace detection parameters: headspace bottle equilibrium temperature: 85°C; quantitative loop temperature: 95°C; transfer line temperature: 105°C; headspace injection port temperature: 200°C; headspace equilibrium time: 35 min; cycle time: 30 min.

[0225] (III) Determination: After the reference solution, blank solution, and test sample spiked solution are equilibrated in the headspace, they are injected into a gas chromatograph and the chromatogram is recorded. The test results of the reference solution are shown in Table 29, and the test sample spiked solution test results are shown in Table 30.

[0226] Table 29 Test results of reference solution

[0227]

[0228] Table 30 Test results of the spiked solution of the test sample

[0229]

[0230] In the reference solution, the RSDs of the peak areas of anhydrous methanol, anhydrous ethanol, isopropanol, dichloromethane and toluene were 1.4, 1.2, 1.3, 1.1 and 1.1, respectively, all less than 10%; in the spiked solution of the test sample, the separation between the chromatographic peaks was greater than 1.5, the tailing factor of each chromatographic peak was less than 1.2, and the theoretical plate number of each chromatographic peak was greater than 10,000. The measured values were accurate.

[0231] Example 11

[0232] (1) The solution preparation is the same as in Example 2.

[0233] (2) Analysis conditions:

[0234] Instrument: Agilent 7890A headspace gas chromatograph, FID detector; chromatographic column: DB-624 (30 m × 0.53 mm, film thickness 3 μm); chromatographic parameters: carrier gas: nitrogen; carrier gas flow rate: 4.0 ml / min; split ratio: 5:1; hydrogen flow rate: 40 mL / min; air flow rate: 400 mL / min; detector temperature: 250°C; column temperature: start at 40°C for 6 min, increase to 150°C at a rate of 10°C / min, and maintain for 5 min.

[0235] Headspace detection parameters: headspace bottle equilibrium temperature: 85°C; quantitative loop temperature: 95°C; transfer line temperature: 105°C; headspace injection port temperature: 200°C; headspace equilibrium time: 25 min; cycle time: 30 min.

[0236] (III) Determination: After the reference solution, blank solution, and test sample spiked solution are equilibrated in the headspace, they are injected into a gas chromatograph and the chromatogram is recorded. The test results of the reference solution are shown in Table 31, and the test sample spiked solution are shown in Table 32.

[0237] Table 31 Test results of reference solution

[0238]

[0239] Table 32 Test results of spiked solution of test sample

[0240]

[0241] In the reference solution, the RSDs of the peak areas of anhydrous methanol, anhydrous ethanol, isopropanol, dichloromethane and toluene were 1.6, 1.8, 1.4, 0.5 and 0.5, respectively, all less than 10%; in the spiked solution of the test sample, the separation between the chromatographic peaks was greater than 1.5, the tailing factor of each chromatographic peak was less than 1.2, and the theoretical plate number of each chromatographic peak was greater than 10,000. The measured values were accurate.

[0242] Comparative Example 1

[0243] Instrument: Agilent 7890A headspace gas chromatograph, FID detector; chromatographic column: DB-624 (30 m × 0.53 mm, film thickness 3 μm); chromatographic parameters: carrier gas: nitrogen; carrier gas flow rate: 4.0 mL / min; split ratio: 5:1; hydrogen flow rate: 40 mL / min; air flow rate: 400 mL / min; detector temperature: 250°C; headspace inlet temperature: 200°C; column temperature: start at 40°C and hold for 5 min, then increase to 120°C at a rate of 10°C / min and hold for 5 min.

[0244] Headspace detection parameters: headspace bottle equilibrium temperature: 80°C; quantitative loop temperature: 90°C; transfer line temperature: 100°C; headspace equilibrium time: 30 min; cycle time: 30 min.

[0245] (1) Blank solution: Place 5.0 mL of N,N-dimethylformamide in a 20 mL headspace vial and seal.

[0246] (2) Reference solution: Weigh 0.3 g of anhydrous methanol, 0.5 g of anhydrous ethanol, 0.5 g of isopropyl alcohol, 0.06 g of dichloromethane, and 0.089 g of toluene, and place them in a 50 mL volumetric flask to which a small amount of N,N-dimethylformamide has been added. Dilute to the mark with N,N-dimethylformamide, and shake to obtain solution A. 5.0 mL of solution A is placed in a 100 mL volumetric flask to which a small amount of N,N-dimethylformamide has been added. Dilute to the mark with N,N-dimethylformamide, and shake to obtain the reference solution. 5.0 mL of the reference solution is placed in a 20 mL headspace vial and sealed.

[0247] (3) Test sample spiked solution: Weigh 0.50 g of sample into a 20 mL headspace vial, add 5.0 mL of reference solution, and seal.

[0248] The reference solution, blank solution, and test sample spiked solution were injected according to the chromatographic conditions and the chromatograms were recorded. The results for the reference solution are shown in Table 33, and the results for the test sample spiked solution are shown in Table 34.

[0249] Table 33 Test results of reference solution

[0250]

[0251] Table 34 Test results of spiked solution of test sample

[0252]

[0253] During the experiment, it was found that the test sample was not easily soluble in N,N-dimethylformamide. The experimental results showed that the chromatographic peak area of each solvent peak in the test sample spiked solution was larger than the chromatographic peak area of each solvent peak in the reference solution, indicating that if N,N-dimethylformamide is used as the blank solvent, the recovery rate of each residual solvent to be tested will be too high. N,N-dimethylformamide is not suitable as a blank solvent for this test method.

[0254] Comparative Example 2

[0255] Instrument: Agilent 7890A headspace gas chromatograph, FID detector; chromatographic column: DB-624 (30 m × 0.53 mm, film thickness 3 μm); chromatographic parameters: carrier gas: nitrogen; carrier gas flow rate: 4.0 mL / min; split ratio: 5:1; hydrogen flow rate: 40 mL / min; air flow rate: 400 mL / min; detector temperature: 250°C; headspace inlet temperature: 200°C; column temperature: start at 40°C and hold for 6 min, then increase to 150°C at a rate of 10°C / min and hold for 5 min.

[0256] Headspace detection parameters: headspace bottle equilibrium temperature: 85°C; quantitative loop temperature: 95°C; transfer line temperature: 105°C; headspace equilibrium time: 30 min; cycle time: 30 min.

[0257] (1) Blank solution: Place 5.0 mL of 50% N,N-dimethylformamide in a 20 mL headspace vial and seal.

[0258] (2) Reference solution: Weigh 0.3 g of anhydrous methanol, 0.5 g of anhydrous ethanol, 0.5 g of isopropyl alcohol, 0.06 g of dichloromethane, and 0.089 g of toluene into a 100 mL volumetric flask to which a small amount of 50% N,N-dimethylformamide has been added. Add 50% N,N-dimethylformamide to dilute to the mark and shake to obtain solution A. Take 5.0 mL of solution A and place it into a 100 mL volumetric flask to which a small amount of 50% N,N-dimethylformamide has been added. Add 50% N,N-dimethylformamide to dilute to the mark and shake to obtain the reference solution. Take 5.0 mL of the reference solution and place it into a 20 mL headspace vial and seal.

[0259] (3) Test sample spiked solution: Weigh 0.25 g of sample into a 20 mL headspace vial, add 5.0 mL of reference solution, and seal.

[0260] The reference solution, blank solution, and test sample spiked solution were injected according to the chromatographic conditions and the chromatograms were recorded. The results for the reference solution are shown in Table 35, and the results for the test sample spiked solution are shown in Table 36.

[0261] Table 35 Test results of reference solution

[0262]

[0263] Table 36 Test results of spiked solution of test sample

[0264]

[0265] During the experiment, it was found that continuous injections left residual toluene in the instrument, resulting in residual interference of chromatographic peaks at the retention time of the toluene chromatographic peak in the subsequent blank solution chromatogram after the injection of the solution containing toluene, indicating that 50% N,N-dimethylformamide is not suitable as a blank solvent for this test method.

[0266] Comparative Example 3

[0267] Instrument: Agilent 7890A headspace gas chromatograph, FID detector; chromatographic column: DB-624 (30 m × 0.53 mm, film thickness 3 μm); chromatographic parameters: carrier gas: nitrogen; carrier gas flow rate: 4.0 mL / min; split ratio: 5:1; hydrogen flow rate: 40 mL / min; air flow rate: 400 mL / min; detector temperature: 250°C; headspace inlet temperature: 200°C; column temperature: start at 40°C and hold for 6 min, increase to 200°C at a rate of 20°C / min, and hold for 5 min.

[0268] Headspace detection parameters: headspace bottle equilibrium temperature: 80°C; quantitative loop temperature: 90°C; transfer line temperature: 100°C; headspace equilibrium time: 30 min; cycle time: 30 min.

[0269] (1) Blank solution: Place 5.0 mL of dimethyl sulfoxide in a 20 mL headspace vial and seal.

[0270] (2) Reference solution: Weigh 0.3 g of anhydrous methanol, 0.5 g of anhydrous ethanol, 0.5 g of isopropanol, 0.06 g of dichloromethane, and 0.089 g of toluene into a 50 mL volumetric flask to which a small amount of dimethyl sulfoxide has been added. Dilute to the mark with dimethyl sulfoxide and shake well to obtain solution A. 5.0 mL of solution A is placed into a 100 mL volumetric flask to which a small amount of dimethyl sulfoxide has been added. Dilute to the mark with dimethyl sulfoxide and shake well to obtain the reference solution. 5.0 mL of the reference solution is placed into a 20 mL headspace vial and sealed.

[0271] (3) Test sample spiked solution: Weigh 0.50 g of sample into a 20 mL headspace vial, add 5.0 mL of reference solution, and seal.

[0272] The reference solution, blank solution, and test sample spiked solution were injected according to the chromatographic conditions and the chromatograms were recorded. The results for the reference solution are shown in Table 37, and the results for the test sample spiked solution are shown in Table 38.

[0273] Table 37 Test results of reference solution

[0274]

[0275] Table 38 Test results of the spiked solution of the test sample

[0276]

[0277] During the experiment, it was found that the test sample was not easily soluble in dimethyl sulfoxide. The experimental results showed that the chromatographic peak area of each solvent peak in the test sample spiked solution was larger than the chromatographic peak area of each solvent peak in the reference solution, indicating that if dimethyl sulfoxide is used as the blank solvent, the recovery rate of each residual solvent to be tested will be too high, and dimethyl sulfoxide is not suitable as a blank solvent for this test method.

Claims

1. A method for determining residual solvents in LXH-2103 using headspace gas chromatography, characterized in that: Prepare blank solution, reference solution and test solution, inject blank solution, reference solution and sample solution into headspace balance respectively, inject into gas chromatograph by headspace injection, record chromatogram, and calculate content by peak area according to external standard method; the residual solvent is anhydrous methanol, anhydrous ethanol, isopropanol, dichloromethane, toluene; The blank solution is an N,N-dimethylformamide solution with a volume concentration of 85% to 95%; The chromatographic conditions include: chromatographic column: a capillary column with cyanopropylphenyl-dimethylpolysiloxane as the stationary phase; column temperature: starting temperature at 38-42°C, maintained for 5-6 minutes, then rising to 150-220°C at a rate of 10-15°C / min, and maintained for 5-8 minutes; The headspace conditions include: headspace bottle equilibrium temperature: 80-90°C, equilibrium time: 25-35 minutes; and cycle time of 30-35 minutes.

2. The method for determining residual solvents in LXH-2103 by headspace gas chromatography according to claim 1, wherein: The chromatographic conditions also include: detector: FID; detector temperature: 245-255° C.; carrier gas: nitrogen; flow rate: 3.8-4.2 mL / min; split ratio: 5:1; hydrogen flow: 35-40 mL / min; and air flow: 350-400 mL / min.

3. The method for determining residual solvents in LXH-2103 by headspace gas chromatography according to claim 2, wherein: The headspace conditions also include: a quantitative loop temperature of 90-100°C; a transmission line temperature of 100-110°C; and a headspace injection port temperature of 200-220°C.

4. The method for determining residual solvents in LXH-2103 by headspace gas chromatography according to claim 1, wherein: The chromatographic column is DB-624, 30m×0.53mm, and has a film thickness of 3μm.

5. The method for determining residual solvents in LXH-2103 by headspace gas chromatography according to claim 1, wherein: The solvent used for dissolving and diluting the reference solution is the blank solution.

6. The method for determining residual solvents in LXH-2103 by headspace gas chromatography according to claim 5, wherein: The concentration of the product LXH-2103 in the test solution is 0.05~0.06g / mL, and the solvent used for dissolution and dilution is a blank solution.

7. The method for determining residual solvents in LXH-2103 by headspace gas chromatography according to claim 1, wherein: The detection limits of the method for residual solvents are: 4 ppm for anhydrous methanol, 8 ppm for anhydrous ethanol, 8 ppm for isopropanol, 6 ppm for dichloromethane, and 1 ppm for toluene.

8. The method for determining residual solvents in LXH-2103 by headspace gas chromatography according to claim 1, wherein: The quantitative limits of the method for residual solvents are: 15 ppm for anhydrous methanol, 25 ppm for anhydrous ethanol, 26 ppm for isopropanol, 19 ppm for dichloromethane, and 4 ppm for toluene.

9. The method for determining residual solvents in LXH-2103 by headspace gas chromatography according to claim 1, wherein: The detection concentration ranges of residual solvents according to the method are as follows: anhydrous methanol concentration is 0.7398 μg / mL to 177.54 μg / mL, anhydrous ethanol concentration is 1.259 μg / mL to 302.10 μg / mL, isopropanol concentration is 1.276 μg / mL to 306.12 μg / mL, dichloromethane concentration is in the range of 0.9405 μg / mL to 37.62 μg / mL, and toluene concentration is 0.2135 μg / mL to 51.24 μg / mL.

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