A method for detecting related substances in polydocanol by gas chromatography

Abstract

The application relates to the technical field of pharmaceutical analysis and detection, in particular to a gas chromatography detection method for related substances in polydocal. The application is aimed at five key related substances, i.e. ethylene glycol, diethylene glycol, triethylene glycol, n-decanol and n-tetradecanol in polydocal, a capillary chromatographic column with polyethylene glycol as a stationary liquid is adopted, through specific program temperature parameter, solution preparation system and detection condition, simultaneous separation and accurate quantification of the five impurities are realized. The method has strong specificity, good precision, high sensitivity, excellent linear relationship and high accuracy. The detection method provided by the application is simple in operation and controllable in parameters, fully meets the requirements of pharmaceutical quality control and registration declaration, and can be widely applied to quality detection of polydocal raw materials and preparations.

Description

Technical Field

[0001] This application relates to the technical field of drug analysis and detection, and in particular to a gas chromatography method for the detection of related substances in polydextrose. Background Technology

[0002] Podocalcitonin is a mixture of polyethylene glycol monododecyl ether and is a commonly used sclerosing agent in clinical practice. It is mainly used to treat diseases such as varicose veins and spider angiomas of the lower extremities. The safety of its clinical application is directly related to the level of impurity control of the drug.

[0003] The synthesis of polidocanol is prone to introducing process impurities such as ethylene glycol, diethylene glycol, triethylene glycol, n-decanol, and n-tetradecyl alcohol. Ethylene glycol, diethylene glycol, and triethylene glycol are residual impurities from the polyethylene glycol raw material used in the synthesis, while n-decanol and n-tetradecyl alcohol are homologues of the fatty alcohols used in the synthesis process. These impurities are all organic impurities that must be strictly controlled according to the ICH Q3A(R2) guideline "Impurities in New Drug Substances" and the requirements for drug registration in China. Excessive levels can increase the risk of hemolysis, local irritation, and even systemic toxicity, directly affecting drug safety. Therefore, establishing a specific, sensitive, and accurate method for the simultaneous detection of these five related substances is a core aspect of polidocanol quality control.

[0004] Currently, the Chinese Pharmacopoeia has not included a legal quality standard for polidocanol. Among the publicly available related technologies, there is no systematic gas chromatography method for the simultaneous separation and quantitative detection of the five specific related substances mentioned above in polidocanol. Existing methods have many shortcomings: some methods cannot achieve baseline separation of the five impurities, and the resolution between adjacent peaks is less than 1.5, which does not meet the requirements of the Chinese Pharmacopoeia and cannot accurately quantify them; some methods have insufficient sensitivity, and the limits of quantitation and detection cannot meet the detection requirement of 0.1% limit; some methods have poor precision and accuracy, and the repeatability of the detection results is poor, which cannot meet the quality control requirements for commercial production.

[0005] Therefore, developing a detection method capable of simultaneously detecting the above five specific related substances in polydextrose is an urgent problem to be solved in this field. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this application provides a gas chromatography method for the detection of related substances in podocarboxylic acid. The proprietary gas chromatography method provided in this application can simultaneously separate and accurately quantify five related substances in podocarboxylic acid: ethylene glycol, diethylene glycol, triethylene glycol, n-decyl alcohol, and n-tetradecyl alcohol. It features high specificity, high precision, good sensitivity, good linearity, and excellent accuracy, fully meeting the methodological validation requirements for the detection of related substances in the Chinese Pharmacopoeia. This method enables precise and stable control of the quality of podocarboxylic acid products, providing reliable technical support for the quality control of podocarboxylic acid.

[0007] This application provides a gas chromatography method for the detection of related substances in polydextrose, employing the following technical solution:

[0008] A gas chromatographic method for detecting related substances in polydocaol, wherein the related substances are organic process impurities introduced during the production process of polydocaol, including ethylene glycol, diethylene glycol, triethylene glycol, n-decyl alcohol and n-tetradecyl alcohol.

[0009] The detection method is as follows: accurately measure the test solution and the reference solution respectively, inject them into the gas chromatograph, record the chromatogram, and calculate the content of each related substance by peak area according to the external standard method;

[0010] The gas chromatography conditions for the detection method are as follows: a capillary column with polyethylene glycol as the stationary phase is used; the column temperature is programmed: the initial temperature is 135-145℃, maintained for 3 min, and then increased to 250℃ at a rate of 5℃ per minute, maintained for 60 min; the injection port temperature is 255-265℃; a flame ionization detector is used, with a detector temperature of 275-285℃; and the injection volume is 1 μL.

[0011] Optionally, the chromatographic column is a capillary chromatographic column with a specification of 30m × 0.25mm and a stationary liquid film thickness of 0.25μm.

[0012] Optionally, the flow rate is 1.6-2.4 ml / min.

[0013] Optionally, the split ratio for chromatographic injection is 20:1.

[0014] Optionally, the formula for calculating the content using the external standard method is as follows:

[0015] ;

[0016] ;

[0017] In the formula, A 对 V represents the peak area of ​​each impurity in the reference solution. 对 This refers to the dilution factor of the reference solution; W 对The sample weight of each impurity reference standard in the reference solution is expressed in mg; P 对 The content of each impurity reference standard is expressed as a percentage (%); A 供 V represents the peak area of ​​each impurity in the test solution; 供 The dilution factor of the test solution; W 供 The sample weight is in mg.

[0018] Optionally, the content limits for each relevant substance are as follows: the content of ethylene glycol, diethylene glycol, triethylene glycol, n-decyl alcohol, and n-tetradecyl alcohol shall not exceed 0.1 wt%.

[0019] Optionally, the system suitability test is also included: inject the reference solution into the gas chromatograph, record the chromatogram, and the elution order is ethylene glycol, n-decyl alcohol, diethylene glycol, n-tetradecyl alcohol, and triethylene glycol. The resolution between each chromatographic peak is not less than 1.5, and the theoretical plate number of each chromatographic peak is not less than 5000.

[0020] Optionally, the test solution is prepared by accurately weighing the polydocaol test sample, dissolving it in anhydrous ethanol, and quantitatively diluting it to prepare a solution containing 20 mg of polydocaol per 1 mL.

[0021] Optionally, the reference solution is prepared by accurately weighing ethylene glycol reference standard, n-decyl alcohol reference standard, diethylene glycol reference standard, n-tetradecyl alcohol reference standard, and triethylene glycol reference standard, dissolving them in anhydrous ethanol, and quantitatively diluting them to prepare a mixed solution containing 20 μg each of ethylene glycol, n-decyl alcohol, diethylene glycol, n-tetradecyl alcohol, and triethylene glycol per 1 mL.

[0022] Optionally, the detection method shall be performed in accordance with General Chapter 0521 of Part IV of the Chinese Pharmacopoeia 2025 Edition.

[0023] In summary, this application has optimized a dedicated gas chromatography detection scheme for five key process impurities in polydextrose. Through specific chromatographic columns, programmed temperature parameters, and solution preparation systems, complete baseline separation of the five impurities has been achieved. Furthermore, comprehensive methodological validation has been completed, demonstrating the following significant advantages:

[0024] (1) Excellent specificity: The detection method of this application achieves complete separation of five impurities through specific temperature program and column selection. The resolution between each impurity peak in the reference solution is greater than 1.5, and the theoretical plate number is greater than 5000 (see Table 1 of Example 2 for details). The solvents anhydrous ethanol and polydextrose are free from interfering peaks at the elution positions of each impurity, completely avoiding mutual interference between impurity peaks and between impurity peaks and matrix peaks, and ensuring accurate qualitative and quantitative analysis.

[0025] (2) Good precision: In the system precision test, the reference solution was injected 6 times consecutively, and the retention time RSD of each impurity peak was less than 1.0%, and the peak area RSD was less than 10% (see Table 2 of Example 2 for details); in the repeatability test, the detection RSD of 6 parallel samples was less than 10%; in the intermediate precision test, 12 samples were tested by different personnel at different times, and the detection RSD of each impurity was less than 10%, and the method detection results were stable and reliable.

[0026] (3) High sensitivity: In the detection method of this application, the quantitation limit concentration of each impurity is not higher than 50% of the limit concentration, the signal-to-noise ratio of the quantitation limit peak S / N≥10, and the peak area RSD of 6 consecutive injections is less than 10%; the detection limit concentration is not higher than 10% of the limit concentration, and the signal-to-noise ratio of the detection limit peak S / N≥3, which can achieve accurate detection of low-content impurities and fully meet the quality control requirements of the 0.1% limit.

[0027] (4) Excellent linearity: The linear correlation coefficient R of each impurity is not less than 0.998 within the range of the quantitation limit concentration to 200% of the limit concentration. The peak area and concentration show a good linear relationship, and the intercept is much less than 25% of the response value of 100% limit concentration, which can ensure accurate quantification within a wide concentration range.

[0028] (5) High accuracy: At the three spiking levels of 50%, 100% and 150% limit concentration, the average recovery rate of each impurity is in the range of 80% to 120%, and the RSD of the recovery rate is less than 10%. The quantitative results of the method are accurate and can truly reflect the actual content of related substances in polydextrose.

[0029] The detection method provided in this application is simple to operate, has controllable parameters, and is robust. It fully complies with the Chinese Pharmacopoeia, ICH guidelines, and relevant requirements for drug registration applications. It can be widely used in the quality control of polidocanol raw materials and preparations, providing reliable technical assurance for the safety of polidocanol. Detailed Implementation

[0030] Before describing the embodiments of this application in detail, it should be understood that the terminology used herein is for the purpose of describing a particular embodiment only. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the term pertains.

[0031] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Furthermore, in the description of this application, unless otherwise stated, "multiple" means two or more.

[0032] The endpoints and any values ​​of the ranges disclosed in this application are not limited to the precise ranges or values, and such ranges or values ​​should be understood to include values ​​close to such ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0033] In this application, the terms "comprising" or "including" are open-ended expressions, meaning they include the content specified in this application but do not exclude other aspects.

[0034] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0035] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0036] In the following examples, polidocanol (batch number 20220301, stored in a sealed container at room temperature) was purchased from Shaanxi Tianyu Pharmaceutical Co., Ltd.; ethylene glycol reference standard (content 99.564%) was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; diethylene glycol reference standard (content 99.651%) was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; triethylene glycol reference standard (content 99.516%) was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; n-decyl alcohol reference standard (content 99.544%) was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; n-tetradecyl alcohol reference standard (content 99.512%) was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; anhydrous ethanol was of chromatographic purity; gas chromatography was performed according to the gas chromatography method in General Chapter 0521 of Part IV of the 2025 edition of the Chinese Pharmacopoeia.

[0037] The present application will be further described in detail below with reference to the embodiments and test results.

[0038] Example 1 – Establishment of Detection Method

[0039] This embodiment establishes a gas chromatography method for the detection of five related substances—ethylene glycol, diethylene glycol, triethylene glycol, n-decanol, and n-tetradecyl alcohol—in polydextrose. Specifically, it includes the following:

[0040] (1) Solution preparation

[0041] Test solution: Weigh 1 g of polydextrose test sample accurately, place it in a 50 mL volumetric flask, dissolve and dilute to the mark with anhydrous ethanol, shake well to obtain a solution containing 20 mg of polydextrose per 1 mL.

[0042] Reference stock solution: Weigh 50 mg each of ethylene glycol, diethylene glycol, triethylene glycol, n-decyl alcohol, and n-tetradecyl alcohol reference standards accurately, place them in the same 50 mL volumetric flask, dissolve and dilute to the mark with anhydrous ethanol, and shake well to obtain the solution.

[0043] Reference solution: Accurately measure 1 mL of the reference stock solution and place it in a 50 mL volumetric flask. Dilute to the mark with anhydrous ethanol and shake well to obtain a mixed solution containing 20 μg each of ethylene glycol, diethylene glycol, triethylene glycol, n-decyl alcohol, and n-tetradecyl alcohol per mL.

[0044] (2) Chromatographic conditions

[0045] Chromatographic column: DB-WAX capillary column (30m×0.25mm, stationary phase film thickness 0.25μm), with polyethylene glycol as the stationary phase.

[0046] Programmed temperature rise: Start at 140℃, hold for 3 minutes, then increase to 250℃ at a rate of 5℃ per minute, and hold for 60 minutes.

[0047] Inlet temperature: 260℃.

[0048] Detector: Flame Ionization Detector (FID), detector temperature 280℃.

[0049] Injection volume: 1 μL.

[0050] Split ratio: 20:1.

[0051] The flow rate was 2.0 ml / min.

[0052] Carrier gas: Nitrogen.

[0053] (3) System applicability requirements

[0054] In the chromatogram of the reference solution, the elution order is ethylene glycol, n-decyl alcohol, diethylene glycol, n-tetradecyl alcohol, and triethylene glycol, with a resolution of not less than 1.5 between each peak and a theoretical plate number of not less than 5000 for each peak.

[0055] (4) Determination method

[0056] First, inject the reference solution to conduct a system suitability test. After confirming that the system meets the requirements, inject the test solution and the reference solution into the gas chromatograph separately and record the chromatograms. Calculate the content of each relevant substance by peak area using the external standard method. The limits are that ethylene glycol, n-decyl alcohol, diethylene glycol, n-tetradecyl alcohol, and triethylene glycol should not exceed 0.1 wt%.

[0057] (5) Calculation formula

[0058] ;

[0059] ;

[0060] In the above formula, A 对 V represents the peak area of ​​each impurity in the reference solution. 对 This refers to the dilution factor of the reference solution; W 对 The sample weight of each impurity reference standard in the reference solution is expressed in mg; P 对 The content of each impurity reference standard is expressed as a percentage (%); A 供 V represents the peak area of ​​each impurity in the test solution; 供 The dilution factor of the test solution; W 供 The sample weight is in mg.

[0061] Example 2 – Methodological Validation

[0062] This embodiment provides a comprehensive methodological validation of the detection method established in Embodiment 1, as detailed below:

[0063] (a) Specificity test

[0064] (1) Solution preparation

[0065] Solvent: Anhydrous ethanol.

[0066] Stock solutions of each impurity standard: Weigh 50 mg each of ethylene glycol, diethylene glycol, triethylene glycol, n-decyl alcohol, and n-tetradecyl alcohol reference standards accurately, place them in 50 mL volumetric flasks, dissolve and dilute to the mark with anhydrous ethanol, and shake well to obtain the stock solutions of each impurity standard.

[0067] Positioning solutions for each impurity: Accurately measure 1 mL of the single standard stock solution for each impurity, place them in 50 mL volumetric flasks, dilute to the mark with anhydrous ethanol, and shake well to obtain the positioning solutions for each impurity.

[0068] Reference solution: Accurately measure 1 mL of each impurity stock solution and place them in the same 50 mL volumetric flask. Dilute to the mark with anhydrous ethanol and shake well to obtain the solution.

[0069] Test solution: Weigh 1 g of polydextrose test sample accurately, place it in a 50 mL volumetric flask, dilute to the mark with anhydrous ethanol, and shake well to obtain the solution.

[0070] Spiked test solution: Weigh 1 g of polydextrose test sample accurately and place it in a 50 mL volumetric flask. Accurately add 1 mL of each of the above-mentioned single-standard stock solutions of impurities, dilute to the mark with anhydrous ethanol, and shake well to obtain the solution.

[0071] (2) Measurement

[0072] The solvent, each positioning solution, the reference solution, the test solution, and the spiked test solution were injected sequentially. The chromatograms were recorded, and the resolution and theoretical plate number were calculated. The detection results are shown in Table 1.

[0073] Table 1 Results of specificity test

[0074]

[0075] As shown in Table 1, the test solutions of anhydrous ethanol and podocarboxylic acid showed no interfering chromatographic peaks at the elution positions of the impurities. The resolution between the impurity peaks in the reference solution was greater than 1.5, the theoretical plate number was greater than 5000, and the peak shapes were good. Therefore, the specificity of the detection method in this application meets the requirements.

[0076] (ii) Precision test

[0077] (1) System precision

[0078] Anhydrous ethanol and the reference solution were injected into the gas chromatograph. The reference solution was injected six times consecutively, and the retention time and peak area of ​​each impurity peak were recorded. The relative standard deviation (RSD) was calculated. The detection results are shown in Table 2.

[0079] Table 2 System precision test results

[0080]

[0081] As shown in Table 2, after six consecutive injections of the reference solution, the RSD of the retention time of each impurity peak was less than 1.0%, and the RSD of the peak area was less than 10%. Therefore, the precision of the detection method system in this application meets the requirements.

[0082] (2) Repeatability

[0083] Six spiked test solutions from the same batch were prepared in parallel and analyzed according to the method in Example 1. The RSD of each impurity was calculated. The test results are shown in Table 3.

[0084] Table 3 Repeatability Test Results

[0085]

[0086] As shown in Table 3, the RSD of each impurity detected in the six parallel samples was less than 10%. Therefore, the repeatability of the detection method in this application meets the requirements.

[0087] (3) Intermediate precision

[0088] Six spiked test solutions from the same batch were prepared in parallel by two different researchers at different times, for a total of 12 solutions. These solutions were then injected and tested according to the method described in Example 1, and the RSD of each impurity was calculated. The test results are shown in Table 4.

[0089] Table 4 Results of intermediate precision test

[0090]

[0091] As shown in Table 4, the RSD of each impurity detected in the 12 samples was less than 10%. Therefore, the intermediate precision of the detection method in this application meets the requirements.

[0092] (iii) Limit of Quantitation Test

[0093] Accurately measure 0.3 mL of ethylene glycol stock solution, 0.1 mL of n-decyl alcohol stock solution, 0.3 mL of diethylene glycol stock solution, 0.1 mL of n-tetradecyl alcohol stock solution, and 0.3 mL of triethylene glycol stock solution, and place them in the same 50 mL volumetric flask. Dilute to the mark with anhydrous ethanol and mix well to obtain the limit of quantitation (LOQ) solution. Inject the LQ solution six times consecutively, record the chromatograms, and ensure that the signal-to-noise ratio (S / N) of each impurity peak is ≥10. Calculate the peak area RSD. The detection results are shown in Table 5.

[0094] Table 5 Results of Limit of Quantitation Test

[0095]

[0096] As shown in Table 5, the quantitation limit concentrations of each impurity in this method are all no higher than 50% of the limit concentration. After six consecutive injections, the RSD of the peak area of ​​each impurity is less than 10%. Therefore, the sensitivity of the detection method in this application meets the requirements.

[0097] (iv) Detection limit test

[0098] Accurately measure 3 mL of the quantitation limit solution from the "Limit of Quantitation" test and place it in a 10 mL volumetric flask. Dilute to the mark with anhydrous ethanol and mix well to obtain the detection limit solution. Inject the detection limit solution into the sample for detection and record the chromatogram. The signal-to-noise ratio (S / N) of each impurity peak is approximately 3. The detection results are shown in Table 6.

[0099] Table 6 Results of the detection limit test

[0100]

[0101] As shown in Table 6, the detection limit concentration of each impurity in this method is no higher than 10% of the limit concentration, demonstrating excellent sensitivity and meeting the detection requirements for low-content impurities.

[0102] (v) Linearity and Range Test

[0103] (1) Solution preparation

[0104] Linear solution 1: Take the limit of quantitation solution from the limit of quantitation test.

[0105] Linear solution 2: Accurately measure 1 mL of each impurity single standard stock solution, place it in a 100 mL volumetric flask, dilute to the mark with anhydrous ethanol, and shake well to obtain the solution.

[0106] Linear solution 3: Accurately measure 1 mL of each impurity single standard stock solution, place it in a 50 mL volumetric flask, dilute to the mark with anhydrous ethanol, and shake well to obtain the solution.

[0107] Linear solution 4: Accurately measure 3 mL of each impurity single standard stock solution, place them in a 100 mL volumetric flask, dilute to the mark with anhydrous ethanol, and shake well to obtain the solution.

[0108] Linear solution 5: Accurately measure 2 mL of each impurity single standard stock solution, place it in a 50 mL volumetric flask, dilute to the mark with anhydrous ethanol, and shake well to obtain the solution.

[0109] (2) Measurement

[0110] The five linear solutions of the above concentrations were injected separately, and the chromatograms were recorded. Linear regression was performed with concentration x as the abscissa and peak area y as the ordinate. The detection results are shown in Table 7.

[0111] Table 7. Linearity and Range Test Results

[0112]

[0113] As shown in Table 7, the linear correlation coefficient R for each impurity is not less than 0.998 within the range of the quantitation limit concentration to 200% of the limit concentration, indicating a good linear relationship between peak area and concentration. Therefore, the linear range of the detection method in this application meets the detection requirements.

[0114] (vi) Accuracy test

[0115] (1) Solution preparation

[0116] Reference stock solution: Accurately weigh 50 mg of each of the following reference standards: ethylene glycol, n-decyl alcohol, diethylene glycol, n-tetradecyl alcohol, and triethylene glycol. Place them in the same 50 mL volumetric flask, dissolve and dilute to the mark with anhydrous ethanol, and shake well.

[0117] Reference solution: Accurately measure 1 mL of the reference stock solution and place it in a 50 mL volumetric flask. Dilute to the mark with anhydrous ethanol and shake well.

[0118] Blank test solution: Weigh 1 g of polydextrose test sample accurately, place it in a 50 mL volumetric flask, dilute to the mark with anhydrous ethanol, and shake well.

[0119] 50% recovery solution: Weigh 1 g of polydextrose test sample accurately, place it in a 50 mL volumetric flask, add 0.5 mL of reference stock solution accurately, dilute to the mark with anhydrous ethanol, shake well, and the solution is ready. Prepare 3 parallel portions.

[0120] 100% recovery solution: Weigh 1 g of polydextrose test sample accurately, place it in a 50 mL volumetric flask, add 1 mL of reference stock solution accurately, dilute to the mark with anhydrous ethanol, shake well, and the solution is ready. Prepare 3 parallel solutions.

[0121] 150% recovery solution: Weigh 1 g of polydextrose test sample accurately, place it in a 50 mL volumetric flask, add 1.5 mL of reference stock solution accurately, dilute to the mark with anhydrous ethanol, shake well, and the solution is ready. Prepare 3 parallel portions.

[0122] (2) Measurement

[0123] The solvent, reference solution, blank test solution, and solutions for each recovery rate were injected sequentially, and the chromatograms were recorded. The recovery rates of each impurity were calculated. The detection results are shown in Table 8.

[0124] Table 8 Accuracy Test Results

[0125]

[0126] As shown in Table 8, at the limit concentrations of 50%, 100%, and 150%, the average recovery rates of each impurity were all within the range of 80% to 120%, and the RSDs of the recovery rates were all less than 10%. This demonstrates that the detection method of this application has excellent accuracy and the quantitative results are accurate and reliable.

[0127] (vii) Durability test

[0128] By changing factors such as flow rate, injection port temperature, detector temperature, initial column temperature, and using different batches of chromatographic columns, the changes in the resolution between each impurity peak in the reference solution, the changes in the theoretical plate number of the peak, the changes in the detection amount of each impurity in the spiked test sample, and the changes in the resolution between the diethylene glycol peak and adjacent chromatographic peaks were investigated.

[0129] (1) Solution preparation

[0130] Solvent: Anhydrous ethanol.

[0131] Reference stock solution: Weigh 50 mg each of ethylene glycol, n-decyl alcohol, diethylene glycol, tetradecyl alcohol, and triethylene glycol accurately, place them in the same 50 ml volumetric flask, dissolve and dilute to the mark with solvent, and shake well to obtain the solution.

[0132] Reference solution: Accurately measure 1 ml of the reference stock solution, place it in a 50 ml volumetric flask, dilute to the mark with solvent, and shake well to obtain the solution.

[0133] Spiked test solution: Weigh 1 g of this product accurately and place it in a 50 ml volumetric flask. Accurately add 1 ml of the reference stock solution, dilute to the mark with solvent, and shake well to obtain the solution.

[0134] (2) Measurement

[0135] The solvent, reference solution, and spiked test solution were injected sequentially. The detection amount of each impurity was calculated based on the peak area using the external standard method. The test results are shown in Tables 9-12.

[0136] Table 9. Durability Test Results (System Suitability 1)

[0137]

[0138] Table 10 Durability Test Results (System Suitability 2)

[0139]

[0140] Table 11 Durability Test Results (Spikeed Test Solution - Impurity Content)

[0141]

[0142] Table 12 Durability Test Results (Spikeed Test Solution - Separation)

[0143]

[0144] As shown in Tables 9-12, by changing the flow rate (2.0 ml / min ± 20%), injection port temperature (260℃ ± 5℃), detector temperature (280℃ ± 5℃), initial column temperature (140℃ ± 5℃), and using different batches of chromatographic columns, the resolution between each impurity peak in the chromatogram of the reference solution was greater than 1.5, and the theoretical plate number was greater than 5000. The RSD of the detection amount of each impurity in the spiked test solution was less than 10%, and the resolution between the diethylene glycol peak and adjacent chromatographic peaks was greater than 1.5. Therefore, the detection method provided in this application has good robustness.

[0145] Example 3 – Detection of related substances in polydextrose sample

[0146] This embodiment utilizes the detection method provided in this application to perform related substance detection on three batches of polydextrose samples produced in pilot production, verifying the stability of the method in practical application.

[0147] Test samples: Three batches of polydextrose alcohol, with production batch numbers 20220301, 20220302 and 20220303 respectively. All of them were prepared by the pilot production line of Shaanxi Tianyu Pharmaceutical Co., Ltd. and stored in a sealed container at room temperature.

[0148] Detection method: Prepare the test solution and reference solution according to the method established in Example 1, set the chromatographic conditions and inject the samples for detection, and calculate the content of ethylene glycol, diethylene glycol, triethylene glycol, n-decyl alcohol and n-tetradecyl alcohol in each batch of test samples by peak area according to the external standard method.

[0149] The test results are shown in Table 13.

[0150] Table 13. Results of related substances testing in three batches of polydextrose samples (unit: %)

[0151]

[0152] As shown in Table 13, the contents of ethylene glycol, diethylene glycol, triethylene glycol, n-decyl alcohol, and n-tetradecyl alcohol in the three batches of polydextrose samples were all far below the limit requirement of 0.1 wt%, and the test results were stable with no abnormal interference peaks. The detection method provided in this application can be stably and reliably applied to product quality testing and control in the industrial production of polydextrose.

[0153] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0154] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A gas chromatographic method for the detection of related substances in polydextrose, characterized in that, The related substances are organic process impurities introduced during the production process of polydextrose, including ethylene glycol, diethylene glycol, triethylene glycol, n-decyl alcohol, and n-tetradecyl alcohol. The detection method is as follows: accurately measure the test solution and the reference solution respectively, inject them into the gas chromatograph, record the chromatogram, and calculate the content of each related substance by peak area according to the external standard method; The gas chromatography conditions for the detection method are as follows: a capillary column with polyethylene glycol as the stationary phase is used; the column temperature is programmed: the initial temperature is 135-145℃, maintained for 3 min, and then increased to 250℃ at a rate of 5℃ per minute, maintained for 60 min; the injection port temperature is 255-265℃; a flame ionization detector is used, with a detector temperature of 275-285℃; and the injection volume is 1 μL.

2. The gas chromatography detection method according to claim 1, characterized in that, The chromatographic column is a capillary column with a specification of 30m × 0.25mm and a stationary film thickness of 0.25μm.

3. The gas chromatography detection method according to claim 1, characterized in that, The split ratio for chromatographic injection is 20:1; optionally, the flow rate is 1.6-2.4 ml / min.

4. The gas chromatography detection method according to claim 1, characterized in that, The formula for calculating the content using the external standard method is as follows: ； ； In the formula, A 对 V represents the peak area of ​​each impurity in the reference solution. 对 This refers to the dilution factor of the reference solution; W 对 The sample weight of each impurity reference standard in the reference solution is expressed in mg; P 对 The content of each impurity reference standard is expressed as a percentage (%); A 供 V represents the peak area of ​​each impurity in the test solution; 供 The dilution factor of the test solution; W 供 The sample weight is in mg.

5. The gas chromatography detection method according to claim 1, characterized in that, The limits for the content of each relevant substance are as follows: the content of ethylene glycol, diethylene glycol, triethylene glycol, n-decanol, and n-tetradecyl alcohol shall not exceed 0.1 wt%.

6. The gas chromatography detection method according to claim 1, characterized in that, It also includes system suitability testing: inject the reference solution into the gas chromatograph, record the chromatogram, and the elution order is ethylene glycol, n-decyl alcohol, diethylene glycol, n-tetradecyl alcohol, triethylene glycol, the resolution between each chromatographic peak is not less than 1.5, and the theoretical plate number of each chromatographic peak is not less than 5000.

7. The gas chromatography detection method according to claim 1, characterized in that, The test solution is prepared as follows: accurately weigh the polydocaine test sample, dissolve it in anhydrous ethanol, and quantitatively dilute it to prepare a solution containing 20 mg of polydocaine per 1 mL.

8. The gas chromatography detection method according to claim 1, characterized in that, The reference solution was prepared as follows: ethylene glycol reference standard, n-decyl alcohol reference standard, diethylene glycol reference standard, n-tetradecyl alcohol reference standard, and triethylene glycol reference standard were accurately weighed, dissolved in anhydrous ethanol, and quantitatively diluted to prepare a mixed solution containing 20 μg each of ethylene glycol, n-decyl alcohol, diethylene glycol, n-tetradecyl alcohol, and triethylene glycol per 1 mL.

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