Method for detecting dimethylamine in levofloxacin
The method of determining dimethylamine in levofloxacin by ion chromatography solves the problems of complex detection methods and high waste liquid treatment costs in the existing technology, realizes a simple, accurate and safe detection of dimethylamine, and improves the detection sensitivity and column stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HUNAN KELUN PHARMA
- Filing Date
- 2026-02-04
- Publication Date
- 2026-05-12
AI Technical Summary
There is a lack of simple and accurate methods for detecting dimethylamine content in levofloxacin in the existing technology. Moreover, existing methods are complicated to operate and require the use of a variety of derivatization reagents and organic solvents, resulting in high waste liquid treatment costs.
Dimethylamine was determined by ion chromatography using a 0.01 mol/L methanesulfonic acid solution as the diluent. The ion chromatograph was configured with a cation exchange column and a conductivity detector, and the dimethylamine content was determined by gradient elution.
It enables simple, accurate, and safe detection of dimethylamine, reduces waste liquid treatment costs, improves detection sensitivity and repeatability, and extends the service life of the chromatographic column.
Smart Images
Figure CN122017066A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of anesthetic production, specifically to a method for detecting dimethylamine in levofloxacin. Background Technology
[0002] Levofloxacin is a quinolone antibiotic with broad-spectrum antibacterial activity and strong antibacterial properties. It exhibits strong antibacterial activity against most Enterobacteriaceae, such as Escherichia coli, Klebsiella spp., Proteus spp., Salmonella spp., Shigella spp., and Gram-negative bacteria like Haemophilus influenzae, Legionella pneumophila, and Neisseria gonorrhoeae. Clinically, it is a core drug for treating respiratory tract infections and genitourinary tract infections. However, levofloxacin synthesis readily produces the byproduct dimethylamine, which has a strong damaging effect on the skin, eyes, and mucous membranes, and is also highly irritating to the respiratory tract.
[0003] Currently, no methods for detecting dimethylamine in levofloxacin have been reported in pharmacopoeias and literature of various countries. Among them, the existing patent (patent publication number CN115616119A, patent name: method for detecting dimethylamine in levofloxacin) uses derivatization high performance liquid chromatography to determine dimethylamine. However, the patent requires the use of multiple derivatization reagents such as sodium tetraborate decahydrate solution, methyl 9-fluorenylmethylchloroformate solution, and citric acid solution for derivatization, which is relatively complicated and requires organic solvents such as acetonitrile, resulting in high waste liquid treatment costs.
[0004] Therefore, there is an urgent need for a method to detect dimethylamine in levofloxacin. Summary of the Invention
[0005] The purpose of this invention is to provide a method for detecting dimethylamine in levofloxacin. This invention uses ion chromatography to determine dimethylamine, which is accurate, sensitive, and has higher safety.
[0006] This invention provides a method for detecting dimethylamine in levofloxacin, comprising the following steps: Weigh out levofloxacin, dissolve and dilute it with diluent, and take the filtrate to obtain the test solution; Take dimethylamine hydrochloride reference standard, dissolve and dilute it with diluent to obtain the reference standard solution; The reference solution and the test solution were injected into an ion chromatograph, respectively, and the chromatograms were recorded. The content of dimethylamine was calculated by peak area using the external standard method.
[0007] The method for detecting dimethylamine in levofloxacin, preferably, uses a 0.01 mol / L methanesulfonic acid solution as the diluent.
[0008] The method for detecting dimethylamine in levofloxacin, preferably, involves using a cation exchange column in the ion chromatograph, a conductivity detector in the ion chromatograph, and a detection mode of the ion chromatograph that is a suppressed conductivity detection.
[0009] In the method for detecting dimethylamine in levofloxacin, preferably, the analytical column of the ion chromatograph is 5mm × 250mm in size, and the guard column is 4mm × 50mm.
[0010] The method for detecting dimethylamine in levofloxacin, preferably, involves the following chromatographic conditions for the ion chromatogram: column temperature of the analytical column is 35°C, flow rate is 0.98-1.02 ml / min, injection volume is 25 µl, and eluent is methanesulfonic acid solution.
[0011] The method for detecting dimethylamine in levofloxacin, preferably, involves a gradient elution of the eluent as follows: the eluent concentration is 0.017-0.023 mol / L for 0-30.0 min, 0.035 mol / L for 30.0-30.1 min, maintained at 0.035 mol / L for 30.1-40.0 min, 0.02 mol / L for 40.0-40.1 min, and maintained at 0.02 mol / L for 40.1-50.0 min.
[0012] The method for detecting dimethylamine in levofloxacin, preferably, involves a gradient elution of the eluent as follows: the eluent concentration is 0.02 mol / L for 0-30.0 min, 0.035 mol / L for 30.0-30.1 min, 0.035 mol / L for 30.1-40.0 min, 0.02 mol / L for 40.0-40.1 min, and 0.02 mol / L for 40.1-50.0 min.
[0013] In the method for detecting dimethylamine in levofloxacin, preferably, the flow rate of the rinsing solution is 1.0 ml / min.
[0014] The method for detecting dimethylamine in levofloxacin, preferably, uses the following formula for calculating dimethylamine: (1) (2) (3) (4) in, A TiThe peak area of the analyte ion in the test solution; A Si The peak area of the analyte ion in the reference solution; D S This is the dilution factor of the reference solution; D T The dilution factor of the test solution; W Si Weighing the reference standard; W Ti Weighing the test sample; 1 and 2 represents the correction factor for the reference solution; The average correction factor; W1 and W2 are the contents of the analyte, respectively; The average content of the analyte; P represents the purity of the reference standard; F is the conversion coefficient between dimethylamine and dimethylamine hydrochloride.
[0015] Beneficial effects:
[0016] The method for detecting dimethylamine in levofloxacin provided by this invention uses ion chromatography to determine the content of dimethylamine in levofloxacin. The method is simple, feasible, specific, accurate, and reproducible, and has the advantages of high detection sensitivity. It can accurately and sensitively detect the content of dimethylamine in levofloxacin raw materials, thereby ensuring the quality of levofloxacin raw materials.
[0017] The present invention features mild reaction conditions, with dilute acid as the mobile phase and diluent, eliminating the need for organic solvents, thus saving on waste liquid treatment costs. It also improves the safety of the testing method, and the chromatographic column is made of inorganic packing material, which has high stability, long column life, and low maintenance costs. Attached Figure Description
[0018] Figure 1 The chromatogram of the spiked solution of the test sample; Figure 2 The chromatogram of the reference solution; Figure 3 This is a graph of a linear equation. Detailed Implementation
[0019] The invention will now be described more fully by way of examples. The invention can be embodied in many different forms and should not be construed as being limited to the exemplary embodiments described herein.
[0020] Example 1
[0021] A method for detecting dimethylamine in levofloxacin, comprising the following steps: S1: Weigh levofloxacin, add diluent to dissolve and dilute, and take the filtrate to obtain the test solution.
[0022] Specifically, weigh 50 mg of levofloxacin accurately, place it in a 25 ml volumetric flask, add an appropriate amount of diluent, sonicate to dissolve and dilute to the mark, shake well, filter, and collect the filtrate.
[0023] S2: Take dimethylamine hydrochloride reference standard, add diluent to dissolve and dilute to obtain reference standard solution.
[0024] Specifically, take dimethylamine hydrochloride reference standard, accurately weigh it, dissolve it in diluent and quantitatively dilute it to prepare a solution containing approximately 2 μg of dimethylamine per 1 ml.
[0025] In steps S1 and S2, the diluent is a 0.01 mol / L methanesulfonic acid solution.
[0026] S3: Take the reference solution and the test solution, inject them into the ion chromatograph, record the chromatograms, and calculate the content of dimethylamine by peak area using the external standard method.
[0027] The analytical column of the ion chromatograph is a cation exchange column, the detector of the ion chromatograph is a conductivity detector, and the detection mode of the ion chromatograph is suppressed conductivity detection.
[0028] The analysis column is Dionex IonPac. TM CS16 (5mm×250mm), with Dionex IonPac protective posts. TM CG16 (4mm×50mm).
[0029] The chromatographic conditions of the ion chromatogram are as follows: column temperature of the analytical column is 35℃, flow rate is 0.98-1.02 ml / min, injection volume is 25 µl, and eluent is methanesulfonic acid solution. Further, the flow rate is 1.0 ml / min.
[0030] The gradient elution method of the eluent is as follows: the eluent concentration is 0.017-0.023 mol / L from 0 to 30.0 min, 0.035 mol / L from 30.0 to 30.1 min, 0.035 mol / L from 30.1 to 40.0 min, 0.02 mol / L from 40.0 to 40.1 min, and 0.02 mol / L from 40.1 to 50.0 min.
[0031] Furthermore, the gradient elution method of the eluent is as follows: the eluent concentration is 0.02 mol / L for 0-30.0 min, 0.035 mol / L for 30.0-30.1 min, 0.035 mol / L for 30.1-40.0 min, 0.02 mol / L for 40.0-40.1 min, and 0.02 mol / L for 40.1-50.0 min.
[0032] The flow rate of the rinsing solution is 1.0 ml / min.
[0033] The formula for calculating dimethylamine in step S3 is as follows: (1) (2) (3) (4) in, A Ti The peak area of the analyte ion in the test solution; A Si The peak area of the analyte ion in the reference solution; D S This is the dilution factor of the reference solution; D T The dilution factor of the test solution; W Si Weighing the reference standard; W Ti Weighing the test sample; 1 and 2 represents the correction factor for the reference solution; This is the average correction factor; W1 and W2 are the contents of the analyte, respectively; The average content of the analyte; P represents the purity of the reference standard; F is the conversion coefficient between dimethylamine and dimethylamine hydrochloride.
[0034] Example 2
[0035] 1. Exclusivity Blank solution (diluent): 0.01 mol / L methanesulfonic acid solution.
[0036] Reference stock solution: Weigh 18.18 mg of dimethylamine hydrochloride, place it in a 200 ml volumetric flask, add diluent to dissolve and dilute to the mark, and shake well.
[0037] Reference solution: Accurately measure 1 ml of the reference stock solution, place it in a 25 ml volumetric flask, dilute to the mark with diluent, and shake well.
[0038] Test solution: Weigh approximately 50 mg of levofloxacin accurately, place it in a 25 ml volumetric flask, add an appropriate amount of diluent, sonicate to dissolve and dilute to the mark, shake well, filter, and collect the filtrate.
[0039] Recovery solution: Weigh approximately 50 mg of levofloxacin accurately and place it in a 25 ml volumetric flask. Accurately add 1 ml of the reference stock solution, add an appropriate amount of diluent, sonicate to dissolve and dilute to the mark, shake well, filter, and collect the filtrate.
[0040] Determination: Inject blank solution, reference solution, test solution and recovery solution into the sample for analysis.
[0041] like Figure 1 and Figure 2 As shown, the results indicate that no impurity peaks interfered with the determination of dimethylamine in either the blank solution or the test solution, demonstrating good method specificity.
[0042] 2. Linear range Using 0.01 mol / L methanesulfonic acid solution as a diluent, take an appropriate amount of the reference standard stock solution under the "Specificity" section and prepare linear solutions of different concentrations L1 to L7 according to Table 1. In addition, take L3 to prepare linear solution L8, and take L5 to prepare linear solution L9. Table 1. Preparation of linear solutions Based on the results of the linearity and range tests, please refer to Table 2 for details. Figure 3 As shown, the linear range of dimethylamine was confirmed to be within the concentration range of 0.2004-4.007 μg / ml. The regression equation was y=0.0909x-0.0007, and the correlation coefficient was r=0.9995. The linearity and range met the requirements.
[0043] Table 2. Results of Linearity and Range Tests 3. Sensitivity Based on the results of the "linearity and range" test, the limit of quantification for dimethylamine was determined to be 0.2004 μg / ml (S / N≥10), and the limit of detection was determined to be 0.1002 μg / ml (S / N≥3).
[0044] 4. Accuracy and Precision Reference stock solution, reference solution, and test solution: same as under "Specificity".
[0045] 50%, 100%, and 150% recovery solutions: Accurately weigh approximately 50 mg of this product and place it in a 25 ml volumetric flask. Accurately add 0.5 ml, 1 ml, and 1.5 ml of the reference stock solution, respectively. Add an appropriate amount of diluent, sonicate to dissolve, and dilute to the mark. Shake well, filter, and collect the filtrate. Prepare three replicates for each concentration.
[0046] The above solutions were injected for analysis, and the results are detailed in Table 3. It is shown that when dimethylamine was added to the test sample at 50%-150% of the limit (0.10%), the recovery rate was calculated. The average recovery rate of dimethylamine was 100.98%, and the RSD (n=9) was 2.82%, indicating that the method has good accuracy and precision.
[0047] Table 3. Results of Accuracy and Precision Tests 5. Durability With other conditions unchanged, the flow rate (1.0 ± 0.2 ml / min) and the initial eluent concentration (0.02 ± 0.003 mol / L methanesulfonic acid solution) were fine-tuned, and the results are detailed in Table 4. After fine-tuning the flow rate and eluent concentration, the average recovery rate of dimethylamine in the recovery solution was 99.58%, and the RSD (n=5) was 2.05%, indicating good robustness of the method.
[0048] Table 4 Durability Test Results In Table 4, at flow rates of 0.8 ml and 1.2 ml, the eluent was a methanesulfonic acid solution with the following concentrations: 0.02 mol / L for 0-30.0 min, 0.035 mol / L for 30.0-30.1 min, 0.035 mol / L for 30.1-40.0 min, 0.02 mol / L for 40.0-40.1 min, and 0.02 mol / L for 40.1-50.0 min.
[0049] In Table 4, eluent 1 and eluent 2 refer to the eluents before the gradient, which are 0.017 mol / L methanesulfonic acid solution and 0.023 mol / L methanesulfonic acid solution, respectively.
[0050] The concentration of eluent 1 was as follows: 0.017 mol / L for 0-30.0 min, 0.035 mol / L for 30.0-30.1 min, maintained at 0.035 mol / L for 30.1-40.0 min, 0.02 mol / L for 40.0-40.1 min, and maintained at 0.02 mol / L for 40.1-50.0 min.
[0051] The concentration of eluent 2 was as follows: 0.023 mol / L for 0-30.0 min, 0.035 mol / L for 30.0-30.1 min, 0.035 mol / L for 30.1-40.0 min, 0.02 mol / L for 40.0-40.1 min, and 0.02 mol / L for 40.1-50.0 min.
[0052] In summary, Example 2 investigated the specificity, linear range, limit of detection and limit of quantitation, accuracy and precision, and robustness. The results show that the proposed method has good specificity, high accuracy, and good robustness.
[0053] The above examples are only for illustrating the present invention. In addition, there are many other different implementations, which can be conceived by those skilled in the art after understanding the concept of the present invention. Therefore, they will not be listed one by one here.
Claims
1. A method for detecting dimethylamine in levofloxacin, characterized in that, Includes the following steps: Weigh out levofloxacin, dissolve and dilute it with diluent, and take the filtrate to obtain the test solution; Take dimethylamine hydrochloride reference standard, dissolve and dilute it with diluent to obtain the reference standard solution; The reference solution and the test solution were injected into an ion chromatograph, respectively, and the chromatograms were recorded. The content of dimethylamine was calculated by peak area using the external standard method.
2. The method for detecting dimethylamine in levofloxacin according to claim 1, characterized in that, The diluent is a 0.01 mol / L methanesulfonic acid solution.
3. The method for detecting dimethylamine in levofloxacin according to claim 2, characterized in that, The analytical column of the ion chromatograph is a cation exchange column, the detector of the ion chromatograph is a conductivity detector, and the detection mode of the ion chromatograph is suppressed conductivity detection.
4. The method for detecting dimethylamine in levofloxacin according to claim 3, characterized in that, The analytical column of the ion chromatograph has a size of 5 mm × 250 mm, and the guard column has a size of 4 mm × 50 mm.
5. The method for detecting dimethylamine in levofloxacin according to claim 4, characterized in that, The chromatographic conditions of the ion chromatograph are as follows: column temperature of the analytical column is 35℃, flow rate is 0.98-1.02 ml / min, injection volume is 25 µl, and eluent is methanesulfonic acid solution.
6. The method for detecting dimethylamine in levofloxacin according to claim 5, characterized in that, The gradient elution mode of the eluent is as follows: the eluent concentration is 0.017-0.023 mol / L from 0 to 30.0 min, 0.035 mol / L from 30.0 to 30.1 min, 0.035 mol / L from 30.1 to 40.0 min, 0.02 mol / L from 40.0 to 40.1 min, and 0.02 mol / L from 40.1 to 50.0 min.
7. The method for detecting dimethylamine in levofloxacin according to claim 6, characterized in that, The gradient elution method of the eluent is as follows: the eluent concentration is 0.02 mol / L from 0 to 30.0 min, 0.035 mol / L from 30.0 to 30.1 min, 0.035 mol / L from 30.1 to 40.0 min, 0.02 mol / L from 40.0 to 40.1 min, and 0.02 mol / L from 40.1 to 50.0 min.
8. The method for detecting dimethylamine in levofloxacin according to claim 7, characterized in that, The flow rate of the rinsing solution is 1.0 ml / min.
9. The method for detecting dimethylamine in levofloxacin according to claim 8, characterized in that, The formula for calculating dimethylamine is as follows: （1） （2） （3） （4） in, A Ti The peak area of the analyte ion in the test solution; A Si The peak area of the analyte ion in the reference solution; D S This is the dilution factor of the reference solution; D T The dilution factor of the test solution; W Si Weighing the reference standard; W Ti Weighing the test sample; 1 and 2 represents the correction factor for the reference solution; The average correction factor; W1 and W2 are the contents of the analyte, respectively; The average content of the analyte; P represents the purity of the reference standard; F is the conversion coefficient between dimethylamine and dimethylamine hydrochloride.