Method for determining nitrosamine impurity N-nitrosociprofloxacin in ciprofloxacin lactate

Abstract

The invention discloses a method for determining nitrosamine impurity N-nitrosociprofloxacin in ciprofloxacin lactate, and relates to the field of substance detection methods, the method adopts a liquid chromatography-mass spectrometry technology, and the liquid chromatography condition comprises that a mobile phase is a mixture of a formic acid solution with the concentration of 0.08%-0.12% and acetonitrile, and the volume ratio of the formic acid solution to the acetonitrile is (45-55): (45-55). According to the present invention, the liquid chromatography (LC) technology and the mass spectrometry (MS) technology are combined, such that the efficient separation ability of the liquid chromatography and the high sensitivity detection ability of the mass spectrometry are combined, the detection sensitivity and the detection accuracy are significantly improved, and the strict requirements of drug quality control and safety are met.

Description

Technical Field

[0001] The present invention relates to the field of substance detection methods, and in particular to a method for determining the nitrosamine impurity N-nitrosociprofloxacin in ciprofloxacin lactate. Background Art

[0002] Ciprofloxacin lactate is a widely used antibacterial drug belonging to the quinolone class of antibiotics. It is widely used in clinical treatment due to its potent antibacterial activity against a wide range of bacteria. However, during the production of ciprofloxacin lactate, a nitrosamine impurity called N-nitrosociprofloxacin may be produced. N-nitrosociprofloxacin is a known potential carcinogen, and its presence poses a serious threat to drug safety. Therefore, accurately measuring the content of N-nitrosociprofloxacin in ciprofloxacin lactate is crucial to ensuring drug quality and safety.

[0003] The formation of nitrosamine impurities is closely related to the production process. During the synthesis of ciprofloxacin lactate, the formation of nitrosamine impurities is closely linked to the production process and material properties. During the synthesis of ciprofloxacin lactate, if nitrite is introduced into the raw materials, or if precursor structures capable of generating nitrosamines (such as those containing secondary amine groups) are present, under suitable chemical conditions (such as certain acidic conditions and temperature), the nitroso group (-NO) provided by the nitrite can react with secondary amine sites in the ciprofloxacin molecule, potentially forming nitrosamine impurities such as N-nitrosociprofloxacin.

[0004] Furthermore, storage conditions (such as temperature, humidity, and light) may also affect the formation of impurities. Although existing production processes have implemented various measures to control the formation of impurities, due to the extremely low content of N-nitrosociprofloxacin and the difficulty in detecting it, existing detection methods still lack accuracy and sensitivity, making it difficult to meet the stringent requirements of drug quality control.

[0005] In recent years, the European Medicines Agency (EMA) has published an updated Q&A document on nitrosamine impurities in medicinal products for human use (Opinion 726 / 2004, No. 5(3)), which clearly stipulates that the acceptable intake of N-nitrosociprofloxacin is 1.5 ppm / day. This regulation further emphasizes the importance of strictly controlling the content of N-nitrosociprofloxacin in ciprofloxacin lactate. However, due to the limitations of sensitivity and selectivity, existing detection methods are unable to accurately measure low concentrations of N-nitrosociprofloxacin, resulting in the inability to effectively assess the safety of the drug. Summary of the Invention

[0006] The object of the present invention is to provide a method for determining the nitrosamine impurity N-nitrosociprofloxacin in ciprofloxacin lactate, so as to solve the problem of low accuracy in the determination of the nitrosamine impurity N-nitrosociprofloxacin in ciprofloxacin lactate in the prior art.

[0007] The present invention provides a method for determining the nitrosamine impurity N-nitrosociprofloxacin in ciprofloxacin lactate, comprising using liquid chromatography-mass spectrometry, wherein the liquid chromatography conditions include using a mobile phase consisting of a mixture of 0.08% to 0.12% formic acid solution and acetonitrile, and the volume ratio of the formic acid solution to the acetonitrile is 45-55:45-55.

[0008] As an optional embodiment, the liquid chromatography conditions further include a column temperature of 32° C. to 38° C. and a flow rate of 0.32 ml / min to 0.38 ml / min.

[0009] As an optional embodiment, in the liquid chromatography, the chromatographic column is a C18 column, and the specifications of the chromatographic column are an inner diameter of 2.1-4.6 mm and a length of 50-150 mm.

[0010] As an optional embodiment, the mass spectrometry conditions include using an electrospray ion source and a detection mode of multiple reaction monitoring.

[0011] As an optional embodiment, the mass spectrometry conditions include a gas flow rate of 4.5L / min~5.5L / min, a gas temperature of 290℃~310℃, a nebulizer pressure of 30psi~40psi, a sheath gas temperature of 240℃~260℃, a sheath gas flow rate of 10L / min~12L / min, a capillary voltage of +3800V~+4200V, a nozzle voltage of +450V~+550V, and a dwell time of 90ms~110ms.

[0012] As an optional embodiment, the content of N-nitrosociprofloxacin is quantitatively analyzed by an external standard method, and its content is determined by calculating the ratio of the peak area of ​​N-nitrosociprofloxacin in the sample to the peak area of ​​a standard with a known concentration range, wherein the injection concentration range of the standard is 0.2 ng / ml to 0.3 ng / ml, and the diluent for the standard is water.

[0013] As an optional implementation, when performing external standard quantitative analysis, the reference solution is measured and injected continuously 5 to 7 times, and the relative standard deviation of the peak area of ​​the reference solution is less than or equal to 15%.

[0014] As an optional implementation manner, in the mass spectrometry conditions, the collision energy range of the monitored ion pairs is 10 eV~40 eV.

[0015] As an optional embodiment, the particle size of the filler particles of the chromatographic column ranges from 2.5 µm to 3.3 µm.

[0016] As an optional embodiment, in the multiple reaction monitoring process, the monitored ion pairs include: The precursor ion 361.1 and the product ion 331.1 were used for quantitative analysis; The precursor ion 361.1 and the product ion 289.1 were used for qualitative analysis; The precursor ion 361.1 and the product ion 271.0 were used for qualitative analysis; The precursor ion 361.1 and the product ion 257.1 were used for qualitative analysis.

[0017] Compared with the prior art, the embodiments of the present invention have the following advantages and beneficial effects: 1. The present invention combines liquid chromatography (LC) and mass spectrometry (MS) to achieve a combination of the efficient separation capability of LC and the highly sensitive detection capability of MS. This not only significantly improves the sensitivity and accuracy of detection, but also meets the stringent requirements of drug quality control and safety. Furthermore, in the present invention, a mixture of 0.08% to 0.12% formic acid solution and acetonitrile is used as the mobile phase, with a volume ratio of formic acid solution to acetonitrile of 45-55:45-55. This effectively improves the elution behavior of N-nitrosociprofloxacin and enhances separation efficiency. The highly sensitive detection capability of mass spectrometry enables detection of extremely low concentrations of the target compound, enabling highly sensitive quantitative analysis.

[0018] 2. The chromatographic column selected in the embodiment of the present invention is a C18 column, which can effectively separate N-nitrosociprofloxacin from other components and reduce interference. The mass spectrometer adopts the multiple reaction monitoring (MRM) mode, which further improves the selectivity and sensitivity of the detection by selecting specific precursor ion and product ion pairs for detection.

[0019] 3. The present invention utilizes an external standard method for quantitative analysis, using standard solutions with concentrations ranging from 0.2 ng / ml to 0.3 ng / ml, and ensuring that the relative standard deviation of the peak area is no greater than 15%, thereby ensuring the accuracy and repeatability of the quantitative results. By optimizing mass spectrometry conditions (such as collision energy and ion source parameters), the reliability of the test results is ensured, enabling accurate detection of N-nitrosociprofloxacin even at low concentrations. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 The first embodiment of the present invention is a test result diagram, wherein Figure 1 (a) is the sample chromatogram, Figure 1 (b) is the enlarged view of the chromatographic peak. Figure 1 (c) is the multiple reaction monitoring chromatogram, Figure 1 (d) is the mass spectrum; Figure 2 is the test result diagram of the blank group, where Figure 2 (a) is the sample chromatogram, Figure 2 (b) is the enlarged view of the chromatographic peak. Figure 2 (c) is the multiple reaction monitoring chromatogram, Figure 2 (d) is the mass spectrum; Figure 3 This is the test result diagram of the concentration 0.5860ng / ml group, where Figure 3 (a) is the sample chromatogram, Figure 3 (b) is the enlarged view of the chromatographic peak. Figure 3 (c) is the multiple reaction monitoring chromatogram, Figure 3 (d) is the mass spectrum; Figure 4 This is the test result diagram of the concentration 0.4395ng / ml group, where Figure 4 (a) is the sample chromatogram, Figure 4 (b) is the enlarged view of the chromatographic peak. Figure 4 (c) is the multiple reaction monitoring chromatogram, Figure 4 (d) is the mass spectrum; Figure 5 This is the test result diagram of the concentration 0.2930ng / ml group, where Figure 5 (a) is the sample chromatogram, Figure 5 (b) is the enlarged view of the chromatographic peak. Figure 5 (c) is the multiple reaction monitoring chromatogram, Figure 5 (d) is the mass spectrum; Figure 6 This is the test result diagram of the concentration 0.1465ng / ml group, where Figure 6 (a) is the sample chromatogram, Figure 6 (b) is the enlarged view of the chromatographic peak. Figure 6 (c) is the multiple reaction monitoring chromatogram, Figure 6 (d) is the mass spectrum; Figure 7 This is the test result diagram of the concentration 0.05860ng / ml group, where Figure 7 (a) is the sample chromatogram, Figure 7 (b) is the enlarged view of the chromatographic peak. Figure 7 (c) is the multiple reaction monitoring chromatogram, Figure 7 (d) is the mass spectrum; Figure 8 This is the test result diagram of the concentration 0.02930ng / ml group, where Figure 8 (a) is the sample chromatogram, Figure 8 (b) is the enlarged view of the chromatographic peak. Figure 8 (c) is the multiple reaction monitoring chromatogram, Figure 8 (d) is the mass spectrum; Figure 9 This is the test result diagram of the concentration 0.01465ng / ml group, where Figure 9 (a) is the sample chromatogram, Figure 9 (b) is the enlarged view of the chromatographic peak. Figure 9 (c) is the multiple reaction monitoring chromatogram, Figure 9 (d) is the mass spectrum; Figure 10 The spectrum obtained is reported as the signal-to-noise ratio of the quantification limit for the concentration 0.01465 ng / ml group; Figure 11 This is the spectrum obtained for detecting the N-nitrosociprofloxacin reference substance; Figure 12 This is the spectrum obtained by detecting the test sample. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0023] Therefore, the detailed description of the embodiments of the present invention provided below is not intended to limit the scope of the claimed invention, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention.

[0024] The embodiment of the present invention provides a method for determining the nitrosamine impurity N-nitrosociprofloxacin in ciprofloxacin lactate, using the following chromatographic conditions and mass spectrometry conditions: (1) Chromatographic conditions Column: Agilent Poroshell 120 EC-C18 4.6×100mm Mobile phase: 0.08%~0.12% formic acid solution-acetonitrile (45~55:45~55) Column temperature: 32°C~38°C; Injection volume: 15~25μl; Flow rate: 0.32ml / min~0.38ml / min.

[0025] (2) Mass spectrometry conditions Ion source: AJS-ESI; Detection mode: MRM; Gas flow: 4.5 L / min–5.5 L / min; Gas temperature: 290°C–310°C; Nebulizer: 30 psi–40 psi; Sheath gas temperature: 240°C–260°C; Sheath gas flow: 10 L / min–12 L / min; Capillary: +3800 V–+4200 V; Delta EMV (+): 180–220 V; Nozzle voltage: +450 V–+550 V; Dwell: 90 ms–110 ms. The monitored ion pairs are shown in Table 1 below: Table 1

[0026] In the above method for determining N-nitrosociprofloxacin in ciprofloxacin lactate raw materials, the content of N-nitrosociprofloxacin is calculated by peak area using the external standard method, the injection concentration of the reference substance is 0.2 ng / ml~0.3 ng / ml, and the diluent is water.

[0027] The embodiments of the present invention specifically optimize the ionization efficiency of N-nitrosociprofloxacin, creating a unique ionization environment that improves sensitivity or reduces background interference, ensuring the accuracy of detection results. Furthermore, this method is highly specific and addresses the challenges of low N-nitrosociprofloxacin content and low detection sensitivity.

[0028] Example 1: A method for determining the nitrosamine impurity N-nitrosociprofloxacin in ciprofloxacin lactate is provided, comprising the following: Test solution: Accurately measure an appropriate amount of this product and dilute it with water to make a solution containing approximately 0.2 mg of ciprofloxacin per 1 ml; Reference solution: Take an appropriate amount of N-nitrosociprofloxacin reference substance, accurately weigh it, dissolve it in dimethyl sulfoxide (DMSO), and quantitatively dilute it to make a stock solution containing approximately 300 ng of N-nitrosociprofloxacin per 1 ml. Accurately measure an appropriate amount of the stock solution and quantitatively dilute it with water to make a solution containing approximately 0.25 ng of N-nitrosociprofloxacin per 1 ml. Chromatographic conditions: Octadecylsilane bonded silica gel as the packing material (Agilent Poroshell 120 EC-C18 4.6 × 100 mm, 2.7 μm or equivalent performance column), 0.1% formic acid solution-acetonitrile (50:50) as the mobile phase, isocratic elution; flow rate, 0.35 ml / min; column temperature, 35°C; injection volume, 20 μL; Mass spectrometry conditions: triple quadrupole mass spectrometer detection, electrospray ionization source; multiple reaction monitoring (MRM) monitoring mode; positive polarity; monitored ions: 361.1→331.1 (quantitative), 361.1→289.1 (qualitative), 361.1→271.0 (qualitative), 361.1→257.1 (qualitative); Gas Flow: 5 L / min; Gas Temp: 300°C; Nebulizer: 35 psi; Sheath Gas Temp: 250°C; Sheath Gas Flow: 11 L / min; Determination method: Accurately measure 20 μl of reference solution and test solution, inject them into liquid chromatography-mass spectrometry instrument respectively, and record the chromatogram; Limit: If there is a peak in the spectrum of the test solution with the same retention time as the impurity N-nitrosociprofloxacin, the peak area calculated by the external standard method shall not exceed 1.25 ppm.

[0029] Test results (1) Exclusivity Representative images of sample spiked system solutions are shown in Figure 2. Figure 1 As shown by Figure 1 (a) As can be seen, the figure shows the change of the intensity of all detected ions over time during the liquid chromatography-mass spectrometry (LC-MS / MS) analysis. In this test, N-nitrosociprofloxacin was detected at about 5.13 minutes; Figure 1 (b) It can be seen that the enlarged figure shows the chromatographic peak at 5.13 minutes. The peak shape is symmetrical and sharp, indicating that the chromatographic separation effect is good and there is no obvious tailing or fronting phenomenon. Figure 1 Figure (c) shows a multiple reaction monitoring (MRM) chromatogram, which displays chromatographic peaks for specific ion pairs. Specifically, the figure displays chromatographic peaks for multiple MRM channels, including 361.1 -> 331.1 (quantitative), 361.1 -> 289.1 (qualitative), and 361.1 -> 271.0 (qualitative). The appearance of these chromatographic peaks indicates that the target compound was effectively detected at these specific ion transitions. In particular, the chromatographic peak at 361.1 -> 331.1 is used for quantitative analysis, and its peak area and height can be used to calculate the concentration of the compound. Figure 1(d) As can be seen, the mass spectrometry data collected at specific time points (4.632 to 5.883 minutes) are shown. The figure shows a significant molecular ion peak with a mass-to-charge ratio (m / z) of 361.1. This peak represents the molecular ion of N-nitrosociprofloxacin, that is, the ion formed during the ionization process of the entire molecule. The figure also shows several important fragment ion peaks with m / z values ​​of 331.1, 289.1, 271.0 and 257.1, respectively. These fragment ions are produced by further fragmentation of the molecular ions in the collision cell of the mass spectrometer. The presence of these fragment ion peaks and their m / z values ​​are consistent with the expected fragments of N-nitrosociprofloxacin, thereby verifying the structure of the target compound.

[0030] The quantification transition mentioned in the figure is 361.1 -> 331.1. This indicates that in multiple reaction monitoring (MRM) mode, the fragmentation of the molecular ion (m / z 361.1) into a specific fragment ion (m / z 331.1) is monitored. This transition is used for quantitative analysis because it typically exhibits high signal intensity and good stability. Qualification transitions include 361.1 -> 289.1, 361.1 -> 271.0, and 361.1 -> 257.1. These transitions are used to confirm the identity of the target compound because they reflect specific structural features of the molecule. The figure also shows the relative intensity ratios of the different fragment ions. For example, the intensity ratio of 361.1 -> 289.1 is 45.4%, and the intensity ratio of 361.1 -> 271.0 is 45.5%. These ratios are consistent with the expected fragmentation pattern of N-nitrosociprofloxacin, further verifying the identity of the target compound.

[0031] Overall, combined Figure 1 、 Figure 11 and Figure 12 It can be seen that neither the blank solvent nor the test sample interferes with the detection, indicating that the method has good specificity, which means that during the analysis process, only the target compound will produce a specific mass spectrometric signal, and other compounds or matrices will not interfere with this process.

[0032] (2) Linear range Accurately measure the N-nitrosociprofloxacin reference substance stock solution (0.0293 mg / ml) and dilute it stepwise with water to prepare reference substance solutions containing 0.586 ng / ml, 0.4395 ng / ml, 0.2930 ng / ml, 0.1465 ng / ml, 0.0586 ng / ml, 0.02930 ng / ml, and 0.01465 ng / ml of LN-nitrosociprofloxacin.

[0033] According to the method of the embodiment of the present invention, sampling and derivatization were carried out, and the sample was injected and analyzed. The results are shown in Table 2. Figure 2-Figure 9 shown.

[0034] Table 2 Results of linear relationship investigation

[0035] The test results showed that within the concentration range of 0.5860 to 0.02930 ng / ml, the linear equation was y=18146.7041x-29.8361, the correlation coefficient was 0.998, and the linear relationship was good.

[0036] (3) Limit of quantification and detection limit According to the test results under "Linearity and Range", the detection limit concentration was determined with a signal-to-noise ratio of ≥3, and the detection limit concentration of N-nitrosociprofloxacin was less than the 10% limit concentration; the quantification limit concentration was determined with a signal-to-noise ratio of ≥10, and the quantification limit concentration was less than the 30% limit concentration. Both the detection limit and the quantification limit met the requirements. The results are shown in Tables 3 and Figure 10 .

[0037] Table 3 Results of detection limit and quantification limit investigation

[0038] (4) Accuracy and precision The accuracy and precision were investigated by adding samples.

[0039] Test solution: Weigh about 20 mg of ciprofloxacin lactate raw material (batch number: 230821, Zhejiang Guobang), place it in a 10 ml volumetric flask, dissolve it in water and dilute it to the scale, and mix it; accurately measure 1 ml, place it in a 10 ml volumetric flask, dilute it with water to the scale, and mix it.

[0040] Preparation of 50% / 100% / 150% sample recovery solution: Accurately weigh approximately 20 mg (9 portions) of ciprofloxacin lactate raw material (batch number: 230821), place it in a 10 ml volumetric flask, dissolve it in water and dilute it to the scale, and mix it evenly; accurately measure 1 ml of each solution, place it in a 10 ml volumetric flask, add 0.5 ml / 1 ml / 1.5 ml of the reference substance stock solution (concentration 3.23 ng / ml) respectively, dilute it with water to the scale, and mix it evenly (3 replicates for each concentration).

[0041] The results were shown in Table 4.

[0042] Table 4 Accuracy and precision inspection results

[0043] Results: The mean recovery of N-nitrosociprofloxacin was 95.76% with an RSD of 6.2%. The experimental results showed that the method had good accuracy and precision within the range of 50-150% of the limit concentration.

[0044] (5) Durability Test solution: Weigh about 20 mg of ciprofloxacin lactate raw material, place it in a 10 ml volumetric flask, dissolve it in water and dilute it to the scale, and mix it; accurately measure 1 ml, place it in a 10 ml volumetric flask, dilute it with water to the scale, and mix it.

[0045] Preparation of sample recovery solution: Accurately weigh about 20 mg of ciprofloxacin lactate raw material, place it in a 10 ml volumetric flask, dissolve it in water and dilute it to the scale, and mix it evenly; accurately measure 1 ml of each solution, place it in a 10 ml volumetric flask, add 1 ml of the reference substance stock solution (concentration 3.23 ng / ml) to each solution, dilute it to the scale with water, and mix it evenly.

[0046] Under the determined basic chromatographic conditions, the liquid phase and mass spectrometry conditions were fine-tuned, and the samples were injected and analyzed. The results are shown in Tables 5 and 6.

[0047] Table 5

[0048] Table 6

[0049] Results: The above chromatographic and mass spectrometric parameters were fine-tuned, and there was no interference from the solvent. The average recovery of N-nitrosociprofloxacin was 108.84% with an RSD of 4.9%, which was less than 15%. The method robustness met the requirements.

[0050] (6) Determination of three batches of samples Multiple batches of ciprofloxacin lactate raw materials were tested using a validated N-nitrosociprofloxacin test method. The results are shown in Table 7.

[0051] Table 7 Detection results of N-nitrosociprofloxacin in three batches of samples

[0052] (7) Verification results summary The verification results of the above tests are summarized in Table 8.

[0053] Table 8 Methodological validation results of impurity N-nitrosociprofloxacin

[0054] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for determining the nitrosamine impurity N-nitrosociprofloxacin in ciprofloxacin lactate, characterized in that: The method comprises adopting liquid chromatography-mass spectrometry technology, wherein the liquid chromatography conditions include adopting a mobile phase of a mixture of 0.08% to 0.12% formic acid solution and acetonitrile, and the volume ratio of the formic acid solution to the acetonitrile is 45 to 55:45 to 55.

2. A method for determining the nitrosamine impurity N-nitrosociprofloxacin in ciprofloxacin lactate according to claim 1, characterized in that, The liquid chromatography conditions also include a column temperature of 32° C. to 38° C. and a flow rate of 0.32 ml / min to 0.38 ml / min.

3. A method for determining the nitrosamine impurity N-nitrosociprofloxacin in ciprofloxacin lactate according to claim 2, characterized in that, In the liquid chromatography, the chromatographic column is a C18 column, and the specifications of the chromatographic column are an inner diameter of 2.1-4.6 mm and a length of 50-150 mm.

4. The method for determining the nitrosamine impurity N-nitrosociprofloxacin in ciprofloxacin lactate according to claim 1, wherein: The mass spectrometry conditions include using an electrospray ion source and a detection mode of multiple reaction monitoring.

5. A method for determining the nitrosamine impurity N-nitrosociprofloxacin in ciprofloxacin lactate according to claim 4, characterized in that, The mass spectrometry conditions include a gas flow rate of 4.5 L / min to 5.5 L / min, a gas temperature of 290°C to 310°C, a nebulizer pressure of 30 psi to 40 psi, a sheath gas temperature of 240°C to 260°C, a sheath gas flow rate of 10 L / min to 12 L / min, a capillary voltage of +3800 V to +4200 V, a nozzle voltage of +450 V to +550 V, and a dwell time of 90 ms to 110 ms.

6. The method for determining the nitrosamine impurity N-nitrosociprofloxacin in ciprofloxacin lactate according to claim 1, wherein: The method includes quantitatively analyzing the content of N-nitrosociprofloxacin by an external standard method, and determining the content of N-nitrosociprofloxacin by calculating the ratio of the peak area of ​​N-nitrosociprofloxacin in the sample to the peak area of ​​a standard within a known concentration range, wherein the injection concentration range of the standard is 0.2 ng / ml to 0.3 ng / ml, and the diluent for the standard is water.

7. The method for determining the nitrosamine impurity N-nitrosociprofloxacin in ciprofloxacin lactate according to claim 6, wherein: When performing quantitative analysis using the external standard method, measure the reference solution and inject it continuously 5 to 7 times. The relative standard deviation of the peak area of ​​the reference solution should be less than or equal to 15%.

8. The method for determining the nitrosamine impurity N-nitrosociprofloxacin in ciprofloxacin lactate according to claim 5, wherein: In the mass spectrometry conditions, the collision energy range of the monitored ion pairs is 10 eV~40 eV.

9. The method for determining the nitrosamine impurity N-nitrosociprofloxacin in ciprofloxacin lactate according to claim 3, wherein: The particle size of the filler particles of the chromatographic column ranges from 2.5 μm to 3.3 μm.

10. The method for determining the nitrosamine impurity N-nitrosociprofloxacin in ciprofloxacin lactate according to claim 4, wherein: During MRM, the monitored ion transitions include: The precursor ion 361.1 and the product ion 331.1 were used for quantitative analysis; The precursor ion 361.1 and the product ion 289.1 were used for qualitative analysis; The precursor ion 361.1 and the product ion 271.0 were used for qualitative analysis; The precursor ion 361.1 and the product ion 257.1 were used for qualitative analysis.

Images