A method for detecting eszopiclone-related substances

Abstract

This invention discloses a method for detecting related substances in eszopiclone, comprising the following steps: taking eszopiclone reference standard, impurity A reference standard, and impurity B reference standard respectively, and diluting them with a diluent adjusted to pH 2.5 to obtain a system suitability solution; preparing eszopiclone test solution and eszopiclone reference standard solution using the above diluent; measuring the system suitability solution, test solution, and reference solution respectively, testing and recording the high performance liquid chromatograms, and calculating the content of each related substance in eszopiclone by the external standard method. After adjusting the pH of the diluent to 2.5, (1) the solution has good stability and does not need to be freshly prepared before use; (2) the retention time of impurity A is consistent with the retention time of impurity A in the spiked solution of the test sample, and the retention times of the other known impurity peaks are consistent with the retention times of each impurity peak in the spiked solution of the test sample. The detection method provided by this invention has better durability and higher accuracy.

Description

Technical Field

[0001] This invention belongs to the field of drug detection technology, and specifically relates to a method for detecting eszopiclone-related substances. Background Technology

[0002] Insomnia is a common health problem that affects the quality and quantity of sleep an individual experiences. Chronic insomnia can lead to complications such as memory loss, mood swings, and weakened immunity, and may even increase the risk of chronic diseases like cardiovascular disease and diabetes, indirectly impacting quality of life and life expectancy.

[0003] Drug therapy is a common treatment for insomnia. Eszopiclone, the dextrorotatory monoisomer of zopiclone, is used for the treatment of short-term and chronic insomnia. Compared to traditional barbiturates and benzodiazepines, eszopiclone is more effective in improving sleep quality and shortening sleep onset time, with fewer adverse reactions and no significant drug tolerance observed with long-term use, making it an ideal sedative-hypnotic drug.

[0004] The structure of zopiclone is as follows:

[0005] Related substances are one of the key quality attributes in drug research, and their content is a direct indicator of drug purity. In the current standards, ChP2020 and USP2022 both contain HPLC detection methods for eszopiclone related substances. Through research, the inventors found that the eszopiclone ChP2020 related substances method has the following defects: (1) The test sample is unstable and needs to be freshly prepared before use; (2) The peak shape of impurity I (impurity A) in the solution, the eszopiclone peak and the eszopiclone peak in the test sample solution are poor and have severe tailing. Moreover, the peak shape does not improve significantly after changing the chromatographic column, indicating poor column durability.

[0006] Compared to the ChP2020 method, the related substances method of eszopiclone USP2022 can effectively separate impurity peaks B, C, D, and A from each other and from the eszopiclone peak, and the peak shapes are good. However, there are still shortcomings: the retention time of impurity A in the impurity A localization solution (14.227 min) is significantly different from that in the spiked solution of the test sample (13.072 min), which is inconsistent.

[0007] In order to better control the quality of eszopiclone, it is urgent to develop a universal method for detecting eszopiclone-related substances. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to provide a method for detecting eszopiclone-related substances. Under the chromatographic conditions provided by the present invention, impurities can be effectively separated from each other and from the main peak, with good peak shapes. The retention time of impurity A is consistent with the retention time of impurity A in the spiked solution of the test sample, and the retention times of the peaks of other known impurities are consistent with the retention times of the impurity peaks in the spiked solution of the test sample. Method verification shows that the method provided by the present invention has good specificity, precision, and accuracy, and can overcome the deficiencies of current standards for detecting eszopiclone-related substances, effectively solving the problems in the background art.

[0009] This invention is achieved through the following technical solution: A method for detecting eszopiclone-related substances includes the following steps: System suitability solution: Take appropriate amounts of eszopiclone reference standard, impurity A reference standard, and impurity B reference standard, dissolve and dilute with diluent to prepare a system suitability solution; Test solution: Take an appropriate amount of eszopiclone test sample, dissolve and dilute with diluent to prepare a test solution; Reference solution: Take an appropriate amount of eszopiclone reference standard, dissolve and dilute with diluent to prepare a reference solution; Assay: Accurately measure the system suitability solution, test solution and reference solution respectively, inject them into the high performance liquid chromatograph, and record the chromatogram; calculate the content of each related substance in eszopiclone according to the chromatogram by the external standard method. The relevant substances include impurities A, B, C, and D, with the following structures: Impurity A ; Impurity B ; Impurity C ; Impurity D ; The diluent is a mixed solution of acetonitrile and sodium dodecyl sulfate-sodium dihydrogen phosphate buffer, with a pH of 2.5; the volume ratio of acetonitrile to buffer in the diluent is 628:1000.

[0010] A further improvement to the present invention is as follows: The method for preparing the system suitability solution is as follows: Take appropriate amounts of eszopiclone reference standard, impurity A reference standard, and impurity B reference standard, add an appropriate amount of diluent, sonicate to dissolve, and dilute to volume with diluent to obtain a solution, wherein the concentration of eszopiclone is 0.04 mg / mL, the concentration of impurity A is 0.04 mg / mL, and the concentration of impurity B is 0.04 mg / mL.

[0011] Further, the preparation method of the test solution is as follows: take an appropriate amount of eszopiclone test sample, accurately weigh it, add an appropriate amount of diluent, sonicate to dissolve, and dilute to volume with diluent to prepare a solution with a concentration of 4 mg / L.

[0012] Further, the preparation method of the reference solution is as follows: take an appropriate amount of eszopiclone reference standard, accurately weigh it, add an appropriate amount of diluent, sonicate to dissolve, and dilute to volume with diluent to prepare a solution with a concentration of 0.004 mg / L.

[0013] A further improvement to the present invention is as follows: The chromatographic conditions of the high-performance liquid chromatograph are as follows: Column: GL Sciences Inertsil ODS-3V, 250mm × 4.6mm, 5μm; Mobile phase: a mixed solution of acetonitrile and sodium dodecyl sulfate-sodium dihydrogen phosphate buffer, with the pH adjusted to 4.0 using phosphoric acid; wherein the volume ratio of acetonitrile to buffer is 628:1000. Flow rate: 1.5 mL / min; Detection wavelength: 220nm; Column temperature: 30℃; Sample chamber temperature: 5℃; Injection volume: 20 mL.

[0014] A further improvement to the present invention is as follows: In the chromatogram of the system suitability solution, the elution order is impurity B peak, impurity A peak, and eszopiclone peak. The resolution between impurity A peak and eszopiclone peak should not be less than 2.0, and the tailing factor of eszopiclone peak should not be greater than 1.5. In the chromatogram of the reference solution, the RSD of the eszopiclone peak area should not exceed 5.0%.

[0015] Furthermore, the chromatogram of the test solution is recorded to 2.7 times the retention time of the eszopiclone peak, the main component.

[0016] Furthermore, in the chromatogram of the test solution, if there are impurity peaks, the content of each impurity shall be calculated by the peak area of ​​eszopiclone using the external standard method. Impurity A shall not exceed 0.10%, impurity B shall not exceed 0.10%, other individual impurities shall not exceed 0.10%, and the total amount of impurities shall not exceed 0.3%.

[0017] A further improvement to the present invention is as follows: The sodium dodecyl sulfate-sodium dihydrogen phosphate buffer solution is prepared as follows: Take appropriate amounts of sodium dodecyl sulfate and sodium dihydrogen phosphate, dissolve them in water, and dilute to a fixed volume to obtain a solution; wherein the concentration of sodium dodecyl sulfate is 8.1 g / L and the concentration of sodium dihydrogen phosphate is 2.1 g / L. Beneficial effects

[0018] Compared with the prior art, the present invention has the following obvious advantages: After adjusting the pH value of the diluent of the present invention from pH 4.0 to pH 2.5, (1) the solution has good stability and does not need to be freshly prepared before use; (2) the retention time of impurity A is consistent with the retention time of impurity A in the spiked solution of the test sample, and the retention times of the positioning peaks of other known impurities are consistent with the retention times of the peaks of each impurity in the spiked solution of the test sample. This indicates that the detection method provided by the present invention has better durability and higher accuracy.

[0019] Method verification shows that the detection method provided by this invention has good specificity, precision and accuracy, and can overcome the defects of the current standard detection method for levozopiclone related substances.

[0020] This invention provides a method for effectively detecting eszopiclone-related substances, helping to assess the production process and quality control of eszopiclone, ensuring its purity and quality, and thus guaranteeing its efficacy and safety. Attached Figure Description

[0021] Figure 1 This is a blank solvent spectrum; Figure 2 Solution chromatograms for system suitability; Figure 3 The chromatogram of the reference solution; Figure 4 The chromatogram of the spiked solution of the test sample; Figure 5 The chromatogram is of the test solution (batch number: 20220901) in Example 1; Figure 6 The chromatogram is of the test solution (batch number: 20221001) in Example 2; Figure 7 The chromatogram of the test solution (batch number: 20221002) in Example 3; Figure 8 The chromatogram is of the test solution (batch number: 20221201) in Example 4; Figure 9 The chromatogram is of the test solution (batch number: 20221202) in Example 5; Figure 10 The chromatogram of the test solution (batch number: 20221203) in Example 6; Figure 11 This is a standard curve of linearity and impurity A in Example 7; Figure 12 This is a standard curve of linearity versus impurity B in Example 7; Figure 13This is a standard curve of linearity versus impurity C in the range of Example 7; Figure 14 This is a standard curve of linearity versus impurity D in Example 7; Figure 15 This is a standard curve of zopiclone in the linear and range parameters of Example 7. Detailed Implementation

[0022] The instruments, chromatographic columns, reagents, reference standards, and samples used in this invention are as follows: Instruments and Columns

[0023] reagents

[0024] Reference

[0025] sample

[0026] The analysis method provided by this invention (1) Chromatographic conditions and detection conditions: The chromatographic and detection conditions of the methods provided by this invention and Comparative Example 1 (Ezopiclone USP2022 Related Matter Analysis Method) are shown in Table 1 below: Table 1

[0027] (2) Impurity A positioning solution: Weigh approximately 10 mg of impurity A reference standard accurately, place it in a 25 mL volumetric flask, dissolve and dilute to the mark with diluent, shake well, and use it as impurity A stock solution; accurately measure 2 mL of impurity A stock solution, place it in a 20 mL volumetric flask, dilute to the mark with diluent, shake well, and use it as impurity A positioning solution.

[0028] (3) Impurity B positioning solution: Weigh approximately 10 mg of impurity B reference standard accurately, place it in a 25 mL volumetric flask, dissolve and dilute to the mark with diluent, shake well, and use it as impurity B stock solution; accurately measure 2 mL of impurity B stock solution, place it in a 20 mL volumetric flask, dilute to the mark with diluent, shake well, and use it as impurity B positioning solution.

[0029] (4) Impurity C positioning solution: Weigh approximately 2 mg of impurity C reference standard accurately, place it in a 10 mL volumetric flask, dissolve and dilute to the mark with diluent, shake well, and use it as impurity C stock solution; accurately measure 2 mL of impurity C stock solution, place it in a 10 mL volumetric flask, dilute to the mark with diluent, shake well, and use it as impurity C positioning solution.

[0030] (5) Impurity D positioning solution: Weigh approximately 10 mg of impurity D reference standard accurately, place it in a 25 mL volumetric flask, dissolve and dilute to the mark with diluent, shake well, and use it as impurity D stock solution; accurately measure 2 mL of impurity D stock solution, place it in a 20 mL volumetric flask, dilute to the mark with diluent, shake well, and use it as impurity D positioning solution.

[0031] (6) Reference solution: Weigh about 10 mg of eszopiclone reference standard accurately, place it in a 25 mL volumetric flask, dissolve and dilute to the mark with diluent, shake well, and use it as the reference standard stock solution; accurately measure 1 mL of the reference standard stock solution, place it in a 100 mL volumetric flask, dilute to the mark with diluent, shake well, and use it as the eszopiclone reference standard solution.

[0032] (7) System suitability solution: Accurately measure 2 mL each of impurity A stock solution, impurity B stock solution and reference stock solution, place them in a 20 mL volumetric flask, dilute to the mark with diluent, shake well, and use as the system suitability solution.

[0033] (8) Test solution: Weigh approximately 40 mg of eszopiclone test sample accurately, place it in a 10 mL volumetric flask, dilute to the mark with diluent, and shake well to obtain the test solution.

[0034] (9) Spiked solution for test sample: Weigh approximately 40 mg of eszopiclone test sample accurately, place it in a 10 mL volumetric flask, add 1 mL each of impurity A stock solution, impurity B stock solution, and impurity D stock solution, add 2 mL of impurity C stock solution, add diluent, sonicate to dissolve and dilute to the mark, shake well, and use as the spiked solution for test sample.

[0035] The system suitability solution, the impurity localization solution, and the spiked solution of the test sample were tested using the methods provided in this invention and Comparative Example 1, respectively. Chromatograms were recorded, and the results are shown in Tables 2 to 4 below: Table 2 System adaptability solution test results

[0036] Table 3 Detection results of each impurity localization solution

[0037] Table 4 Detection results of the spiked solution of the test sample

[0038] in conclusion: The present invention provides a method in which the retention times of the positioning peaks of impurities B, C, and D are consistent with the retention times of the peaks of each impurity in the spiked solution of the test sample, and the positioning retention time of impurity A is consistent with the retention time of impurity A in the spiked solution of the test sample. Each impurity can be effectively separated from each other and from the main peak, and the peak shape is good.

[0039] Comparative Example 1 provides the following method: Impurity B, Impurity C, Impurity D, and Impurity A peaks can be effectively separated from each other and from the eszopiclone peak, with good peak shapes. The retention times of the locating peaks of Impurities B, C, and D are consistent with the retention times of the impurity peaks in the spiked solution of the test sample. However, the locating retention time of Impurity A (14.227 min) differs significantly from the retention time of Impurity A in the spiked solution of the test sample (13.072 min).

[0040] In summary, through data comparison, the present invention can overcome the defects of the method provided in Comparative Example 1.

[0041] Examples 1-6 Sample Testing 1. Analytical Methods: Chromatographic and detection conditions are shown in Table 1.

[0042] Test solution, reference solution, and system suitability solution: The preparation method is as described in the analytical method provided in this invention.

[0043] 2. Determination of eszopiclone active pharmaceutical ingredient sample: Following the related substances analysis method for eszopiclone, related substances in six batches of active pharmaceutical ingredients were determined, and the chromatograms were recorded. Figures 5 to 10 As shown in Table 5 below, the results are as follows.

[0044] Table 5 Sample Measurement Results

[0045] The results showed that the related substances determination results of all six batches of eszopiclone active pharmaceutical ingredient samples met the requirements.

[0046] Example 7 Validation of the detection method 1. Precision (1) Instrument precision Take the reference solution and repeat the determination 6 times according to the relevant substance analysis method. Calculate the RSD of peak area and retention time. The results are shown in Tables 6 to 9.

[0047] Table 6 Results of instrument precision measurement (Instrument No.: JQ1312)

[0048] Table 7 Instrument precision results (Instrument No.: JQ1316-VWD)

[0049] Table 8 Instrument precision results (Instrument No.: JQ1312-PDA)

[0050] Table 9 Instrument precision results (Instrument No.: QC-M-182)

[0051] The results show that the eszopiclone related substances analysis method has good instrument precision.

[0052] (2) Repeatability Test solution, reference solution, and system suitability solution: The preparation method is as described in the analytical method provided in this invention.

[0053] Spiked solution for test sample (prepare 6 parallel portions): The preparation method is as described in the analytical method provided in this invention.

[0054] Six spiked solutions of the test sample were analyzed according to the related substances analysis method of eszopiclone. The recoveries of impurities A and B, as well as the RSDs of other individual impurities and total impurities in the six spiked solutions of the test sample were investigated. The results are shown in Table 10.

[0055] Table 10 Repeatability Test Results

[0056] The results showed that the eszopiclone related matter analysis method had good reproducibility.

[0057] (3) Intermediate precision Test solution, reference solution, and system suitability solution: The preparation method is as described in the analytical method provided in this invention.

[0058] Spiked solution for test sample (prepare 6 parallel portions): The preparation method is as described in the analytical method provided in this invention.

[0059] Different personnel, on different dates, and using different instruments, determined the spiked solution of the test sample according to the related substances analysis method of eszopiclone. The recovery rate of impurity A and impurity B and the RSD of other individual impurities and total impurities in the spiked solution of the test sample (a total of 12 samples, including 6 samples under the repeatability item) were investigated. The results are shown in Table 11.

[0060] Table 11 Results of intermediate precision determination

[0061] The results showed that the intermediate precision of the eszopiclone related matter analysis method was good.

[0062] 2. Limit of detection and limit of quantitation The detection limit and quantitation limit were determined using the signal-to-noise ratio method, with the concentration at a signal-to-noise ratio of approximately 3:1 used as the detection limit and the concentration at a signal-to-noise ratio of approximately 10:1 used as the quantitation limit.

[0063] (1) Detection limit of impurity A Accurately measure 3 mL of the quantitation limit solution for impurity A and place it in a 10 mL volumetric flask. Dilute to the mark with diluent and shake well. This solution serves as the detection limit solution for impurity A, with a concentration of 0.02459 μg / mL, which is 0.61% of the limit.

[0064] (2) Limit of quantification for impurity A Accurately measure 0.1 mL of the impurity A stock solution under the linearity and range section, place it in a 50 mL volumetric flask, dilute to the mark with diluent, and shake well. Accurately measure 1 mL of this solution, place it in a 10 mL volumetric flask, dilute to the mark with diluent, and shake well. This solution serves as the limit of quantitation solution for impurity A, with a concentration of 0.08198 μg / mL, which is 2.05% of the limit.

[0065] Take the limit of quantitation solution of impurity A, and repeat the injection 6 times to examine the peak area RSD. The results are shown in Table 12.

[0066] Table 12 Results of Limit of Quantitation Determination for Impurity A

[0067] The results showed that the quantitation limit of impurity A had good repeatability.

[0068] (3) Detection limit of impurity B Accurately measure 3 mL of the impurity B quantitation limit solution and place it in a 10 mL volumetric flask. Dilute to the mark with diluent and shake well. This solution serves as the impurity B detection limit solution with a concentration of 0.00247 μg / mL, which is 0.062% of the limit.

[0069] (4) Limit of quantification for impurity B Accurately measure 0.1 mL of the impurity B stock solution under the linearity and range section, place it in a 50 mL volumetric flask, dilute to the mark with diluent, and shake well. Accurately measure 1 mL of this solution, place it in a 100 mL volumetric flask, dilute to the mark with diluent, and shake well. This solution serves as the limit of quantitation solution for impurity B, with a concentration of 0.00823 μg / mL, which is 0.21% of the limit.

[0070] Take the limit of quantitation solution of impurity B, repeat the injection 6 times, and examine the peak area RSD. The results are shown in Table 13.

[0071] Table 13 Results of Impurity B Quantitation Limit Determination

[0072] The results showed that the quantitation limit of impurity B had good repeatability.

[0073] (5) Detection limit of impurity C Accurately measure 3 mL of the impurity C quantitation limit solution and place it in a 10 mL volumetric flask. Dilute to the mark with diluent and shake well. This solution serves as the impurity C detection limit solution with a concentration of 0.00467 μg / mL, which is 0.12% of the limit.

[0074] (6) Limit of quantification for impurity C Accurately measure 0.2 mL of the impurity C stock solution under the linearity and range section, place it in a 50 mL volumetric flask, dilute to the mark with diluent, and shake well. Accurately measure 1 mL of this solution, place it in a 50 mL volumetric flask, dilute to the mark with diluent, and shake well. This solution serves as the limit of quantitation solution for impurity C, with a concentration of 0.01557 μg / mL, which is 0.39% of the limit.

[0075] Take the limit of quantitation solution of impurity C, repeat the injection 6 times, and examine the peak area RSD. The results are shown in Table 14.

[0076] Table 14 Results of Impurity C Quantitation Limit Determination

[0077] The results showed that the quantitation limit of impurity C had good repeatability.

[0078] (7) Detection limit of impurity D Accurately measure 3 mL of the impurity D quantitation limit solution and place it in a 10 mL volumetric flask. Dilute to the mark with diluent and shake well. This solution serves as the impurity D detection limit solution with a concentration of 0.00760 μg / mL, which is 0.19% of the limit.

[0079] (8) Limit of quantification for impurity D Accurately measure 0.1 mL of the impurity D stock solution under the linearity and range section, place it in a 50 mL volumetric flask, dilute to the mark with diluent, shake well, accurately measure 3 mL of the solution, place it in a 100 mL volumetric flask, dilute to the mark with diluent, and use it as the limit of quantitation solution for impurity D with a concentration of 0.02532 μg / mL, which is 0.63% of the limit.

[0080] Take the limit of quantitation solution of impurity D, and repeat the injection 6 times to examine the peak area RSD. The results are shown in Table 15.

[0081] Table 15 Results of Impurity D Quantitation Limit Determination

[0082] The results showed that the quantitation limit of impurity D had good repeatability.

[0083] (9) Limit of detection of eszopiclone Accurately measure 3 mL of eszopiclone quantitation limit solution and place it in a 10 mL volumetric flask. Dilute to the mark with diluent and shake well. This is the eszopiclone detection limit solution with a concentration of 0.02462 μg / mL, which is 0.62% of the limit.

[0084] (10) Limit of quantification of eszopiclone Accurately measure 0.1 mL of eszopiclone stock solution from the linearity and range section, place it in a 50 mL volumetric flask, dilute to the mark with diluent, and shake well. Accurately measure 1 mL of this solution, place it in a 10 mL volumetric flask, dilute to the mark with diluent, and shake well. This solution serves as the eszopiclone limit of quantitation solution, with a concentration of 0.08208 μg / mL, which is 2.05% of the limit.

[0085] Take eszopiclone quantitation limit solution, inject it repeatedly 6 times, and examine the peak area RSD. The results are shown in Table 16.

[0086] Table 16 Results of Eszopiclone Limit of Quantification Determination

[0087] The results showed that eszopiclone had good reproducibility at the limit of quantitation.

[0088] 3. Linearity and Range Weigh approximately 10 mg of impurity A reference standard accurately, place it in a 25 mL volumetric flask, dissolve and dilute to the mark with diluent, and shake well to prepare impurity A stock solution.

[0089] Weigh approximately 10 mg of impurity B reference standard accurately, place it in a 25 mL volumetric flask, dissolve and dilute to the mark with diluent, and shake well to prepare impurity B stock solution.

[0090] Weigh approximately 2 mg of impurity C reference standard accurately, place it in a 10 mL volumetric flask, dissolve and dilute to the mark with diluent, and shake well to prepare impurity C stock solution.

[0091] Weigh approximately 10 mg of impurity D reference standard accurately, place it in a 25 mL volumetric flask, dissolve and dilute to the mark with diluent, and shake well to prepare impurity D stock solution.

[0092] Weigh approximately 10 mg of eszopiclone reference standard accurately, place it in a 25 mL volumetric flask, dissolve and dilute to the mark with diluent, and shake well to prepare eszopiclone stock solution.

[0093] Accurately measure 2 mL each of impurity A stock solution, impurity B stock solution, impurity D stock solution, and eszopiclone stock solution, and 4 mL of impurity C stock solution, place them in the same 20 mL volumetric flask, dilute to the mark with diluent, and shake well to obtain the linear stock solution.

[0094] Accurately measure 0.2 mL, 0.5 mL, 0.8 mL, 1.0 mL, 1.2 mL, and 2.0 mL of the linear stock solution and place them in 10 mL volumetric flasks respectively. Dilute to the mark with diluent and shake well to obtain solutions of linearity 1, linearity 2, linearity 3, linearity 4, linearity 5, and linearity 6.

[0095] Accurately measure linearity 1 to linearity 6 solutions and solutions at the limit of quantitation for each impurity, inject them separately into the liquid chromatograph, record the chromatograms, calculate the linear regression equation, and see the results. Figures 11 to 15 And Tables 17 to 21.

[0096] Table 17 Results of linear determination of impurity A

[0097] The results showed that impurity A exhibited good linearity within the concentration range of 0.08198–8.1980 μg / mL. The linear regression equation was: y = 24205x - 510.57, r = 0.9999.

[0098] Table 18 Results of linearity determination for impurity B

[0099] The results showed that impurity B exhibited good linearity within the concentration range of 0.00823–8.2320 μg / mL. The linear regression equation was: y = 34257x - 381.66, r = 1.

[0100] Table 19 Results of linearity determination of impurity C

[0101] The results showed that impurity C exhibited good linearity within the concentration range of 0.01557–7.7842 μg / mL. The linear regression equation was: y = 31438x - 406.84, r = 1.

[0102] Table 20 Results of linearity determination of impurity D

[0103] The results showed that impurity D exhibited good linearity within the concentration range of 0.02532–8.4396 μg / mL. The linear regression equation was: y = 23171x - 464.95, r = 0.9999.

[0104] Table 21 Results of the linearity determination of eszopiclone

[0105] The results showed that eszopiclone exhibited good linearity within the concentration range of 0.08208–8.2076 μg / mL. The linear regression equation was: y = 27882x - 759.43, r = 0.9999.

[0106] 4. Accuracy Impurity A stock solution and Impurity B stock solution: see the Linearity and Range section for preparation methods.

[0107] Impurity stock solution: Accurately measure 5 mL each of impurity A stock solution and impurity B stock solution, place them in a 50 mL volumetric flask, dilute to the mark with diluent, and shake well.

[0108] Impurity A Quantitative Limit Stock Solution: Accurately measure 0.1 mL of Impurity A stock solution and place it in a 50 mL volumetric flask. Dilute to the mark with diluent and shake well.

[0109] Impurity B Quantitative Limit Stock Solution: Accurately measure 0.1 mL of impurity B stock solution, place it in a 50 mL volumetric flask, dilute to the mark with diluent, and shake well.

[0110] Test solution: Weigh approximately 40 mg of this product accurately, place it in a 10 mL volumetric flask, add diluent, sonicate to dissolve and dilute to the mark, and shake well.

[0111] Reference solution: Weigh approximately 10 mg of eszopiclone reference standard accurately, place it in a 25 mL volumetric flask, dissolve and dilute to the mark with diluent, and shake well to prepare the reference stock solution; accurately measure 1 mL of the reference stock solution, place it in a 100 mL volumetric flask, dilute to the mark with diluent, and shake well.

[0112] System suitability solution: Accurately measure 2 mL each of impurity A stock solution, impurity B stock solution, and reference stock solution, place them in a 20 mL volumetric flask, dilute to the mark with diluent, and shake well.

[0113] Quantitative limit test sample spiking solution: Weigh approximately 40 mg of this product accurately and place it in a 10 mL volumetric flask. Accurately add 1 mL of impurity A quantitative limit stock solution and 0.1 mL of impurity B quantitative limit stock solution. Dissolve and dilute to the mark with diluent, and shake well to obtain the quantitative limit test sample spiking solution (prepare 3 parallel portions).

[0114] 80% spiked solution for test sample: Weigh approximately 40 mg of this product accurately and place it in a 10 mL volumetric flask. Accurately add 0.8 mL of impurity stock solution, add diluent, sonicate to dissolve and dilute to the mark, shake well, and prepare the 80% spiked solution for test sample (prepare 3 parallel portions).

[0115] 100% test sample spiking solution: Weigh approximately 40 mg of this product accurately and place it in a 10 mL volumetric flask. Accurately add 1 mL of impurity stock solution, add diluent, sonicate to dissolve and dilute to the mark, shake well, and prepare a 100% test sample spiking solution (prepare 3 parallel portions).

[0116] 120% test sample spiking solution: Weigh approximately 40 mg of this product accurately and place it in a 10 mL volumetric flask. Accurately add 1.2 mL of impurity stock solution, add diluent, sonicate to dissolve and dilute to the mark, shake well, and prepare a 120% test sample spiking solution (prepare 3 parallel portions).

[0117] Accurately measure each of the above solutions and inject them into the liquid chromatograph. Record the chromatograms and calculate the recovery rate and RSD of impurity A and impurity B in the spiked solution of the test sample. The results are shown in Tables 22 and 23.

[0118] Table 22 Accuracy Measurement Results of Impurity A

[0119] Table 23 Accuracy Measurement Results of Impurity B

[0120] The results showed that the eszopiclone related substances analysis method had good accuracy.

[0121] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent transformations or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for detecting eszopiclone-related substances, characterized in that, Includes the following steps: System suitability solution: Take appropriate amounts of eszopiclone reference standard, impurity A reference standard, and impurity B reference standard, dissolve and dilute with diluent to prepare a system suitability solution; Test solution: Take an appropriate amount of eszopiclone test sample, dissolve and dilute with diluent to prepare a test solution; Reference solution: Take an appropriate amount of eszopiclone reference standard, dissolve and dilute with diluent to prepare a reference solution; Assay: Accurately measure the system suitability solution, test solution and reference solution respectively, inject them into the high performance liquid chromatograph, and record the chromatogram; calculate the content of each related substance in eszopiclone according to the chromatogram by the external standard method. The relevant substances include impurities A, B, C, and D, with the following structures: Impurity A Impurity B Impurity C Impurity D ; The diluent is a mixed solution of acetonitrile and sodium dodecyl sulfate-sodium dihydrogen phosphate buffer, with a pH of 2.5; the volume ratio of acetonitrile to buffer in the diluent is 628:1000. The chromatographic conditions of the high-performance liquid chromatograph are as follows: Column: GL Sciences Inertsil ODS-3V, 250mm × 4.6mm, 5µm; Mobile phase: a mixed solution of acetonitrile and sodium dodecyl sulfate-sodium dihydrogen phosphate buffer, with the pH adjusted to 4.0 using phosphoric acid; wherein the volume ratio of acetonitrile to buffer is 628:1000. Flow rate: 1.5 mL / min; Detection wavelength: 220nm; Column temperature: 30℃; Sample chamber temperature: 5℃; Injection volume: 20µL.

2. The method for detecting eszopiclone-related substances according to claim 1, characterized in that: The system suitability solution is prepared as follows: Take appropriate amounts of eszopiclone reference standard, impurity A reference standard, and impurity B reference standard, add an appropriate amount of diluent, dissolve by sonication, and dilute to volume with diluent to obtain a solution; wherein the concentration of eszopiclone is 0.04 mg / mL. The concentration of impurity A is 0.04 mg / mL, and the concentration of impurity B is 0.04 mg / mL.

3. The method for detecting eszopiclone-related substances according to claim 1, characterized in that: The test solution is prepared as follows: Take an appropriate amount of eszopiclone test sample, accurately weigh it, add an appropriate amount of diluent, sonicate to dissolve, and dilute to volume with diluent to prepare a solution with a concentration of 4 mg / mL.

4. The method for detecting eszopiclone-related substances according to claim 1, characterized in that: The preparation method of the reference solution is as follows: Take an appropriate amount of eszopiclone reference standard, accurately weigh it, add an appropriate amount of diluent, sonicate to dissolve, and dilute to volume with diluent to prepare a solution with a concentration of 0.004 mg / mL.

5. The method for detecting eszopiclone-related substances according to claim 1, characterized in that: In the chromatogram of the system suitability solution, the elution order is impurity B peak, impurity A peak, and eszopiclone peak. The resolution between impurity A peak and eszopiclone peak shall not be less than 2.0, and the tailing factor of eszopiclone peak shall not be greater than 1.

5. In the chromatogram of the reference solution, the RSD of the eszopiclone peak area shall not exceed 5.0%.

6. The method for detecting eszopiclone-related substances according to claim 1, characterized in that: The chromatogram of the test solution was recorded up to 2.7 times the retention time of the eszopiclone peak, the main component.

7. The method for detecting eszopiclone-related substances according to claim 6, characterized in that: If there are impurity peaks in the chromatogram of the test solution, the content of each impurity shall be calculated by the peak area of ​​eszopiclone using the external standard method. Impurity A shall not exceed 0.10%, impurity B shall not exceed 0.10%, other individual impurities shall not exceed 0.10%, and the total amount of impurities shall not exceed 0.3%.

8. The method for detecting eszopiclone-related substances according to claim 1, characterized in that: The sodium dodecyl sulfate-sodium dihydrogen phosphate buffer solution is prepared as follows: Take appropriate amounts of sodium dodecyl sulfate and sodium dihydrogen phosphate, dissolve them in water, and dilute to a fixed volume to obtain a solution; wherein the concentration of sodium dodecyl sulfate is 8.1 g / L and the concentration of sodium dihydrogen phosphate is 2.1 g / L.

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