A pretreatment method and a detection method for ciprofloxacin in water bodies

Abstract

The present invention discloses a pretreatment method and a detection method for ciprofloxacin in water. The pretreatment method for ciprofloxacin in water comprises the following steps: S1. performing a secondary amine derivatization reaction on the water sample to be tested with nitrite to obtain a liquid containing a preliminary derivative of ciprofloxacin; S2. performing a carboxyl derivatization reaction on the liquid containing the preliminary derivative of ciprofloxacin with a carboxyl derivatization reagent to obtain a test solution containing a derivative of ciprofloxacin. The pretreatment method for ciprofloxacin in water established by the present invention through secondary amine derivatization and carboxyl derivatization of ciprofloxacin can obtain a target peak with a symmetric, sharp and non-tailing peak shape when used in gas chromatography-tandem mass spectrometry, and has a short determination time, and can produce a peak within 10 minutes. At the same time, the detection method established relying on the pretreatment method for ciprofloxacin in water has a low detection limit, reaching the ng / L level, a high sample spiking recovery rate, and high precision and accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of analytical detection, and more specifically, to a pretreatment method and a detection method for ciprofloxacin in water bodies. Background Art

[0002] Quinolones (QNs) belong to the derivatives of piromidic acid in chemical structure, and play an antibacterial role by inhibiting bacterial DNA gyrase. Moreover, they also have the characteristics of broad-spectrum antibacterial property and high antibacterial efficiency, and have now been widely used in the livestock and poultry breeding industry and the aquaculture industry. As one of the third-generation quinolones, ciprofloxacin (CIP) is widely used in the treatment of diseases in livestock and poultry breeding and aquaculture due to its good bactericidal effect on Gram-negative bacteria. The widespread use of ciprofloxacin has led to its entry into the ecosystem and water environment, where it accumulates in water bodies such as lakes and rivers, polluting the water bodies and threatening human health. Therefore, the detection of ciprofloxacin in water bodies deserves attention.

[0003] Currently, most of the methods for detecting ciprofloxacin are high-performance liquid chromatography, liquid chromatography-tandem mass spectrometry, and enzyme-linked immunosorbent assay, and gas chromatography-tandem mass spectrometry (GC-MS) is less used.

[0004] Therefore, it is of great significance to develop a pretreatment method for ciprofloxacin in water bodies for gas chromatography-tandem mass spectrometry (GC-MS). Summary of the Invention

[0005] The purpose of the present invention is to solve the deficiencies of the prior art and provide a pretreatment method and a detection method for ciprofloxacin in water bodies for gas chromatography-tandem mass spectrometry (GC-MS).

[0006] To achieve the above purpose, the technical solutions adopted by the present invention are as follows:

[0007] In the first aspect, the present invention provides a pretreatment method for ciprofloxacin in water bodies, including the following steps:

[0008] S1. Perform a secondary amine derivatization reaction on the water sample to be tested with nitrite to obtain a liquid containing a preliminary derivative of ciprofloxacin;

[0009] S2. Perform a carboxyl derivatization reaction on the liquid containing the preliminary derivative of ciprofloxacin with a carboxyl derivatization reagent to obtain a test solution containing a ciprofloxacin derivative (CIP derivative).

[0010] Preferably, in step S1, the nitrite is at least one of sodium nitrite and potassium nitrite.

[0011] In the present invention, the nitrite can be first configured into a nitrite solution before use, and the concentration of the nitrite solution ≤ the saturation concentration of the nitrite.

[0012] Preferably, the volume-mass ratio of the water body to be measured and the nitrite is 1 mL: (0.0001 - 0.86) g.

[0013] Preferably, in step S1, the temperature of the secondary amine derivatization reaction is 0 - 10 °C, and the time is 10 - 180 min.

[0014] More preferably, in step S1, the temperature of the secondary amine derivatization reaction is 0 - 5 °C.

[0015] Preferably, in step S1, the pH value of the secondary amine derivatization reaction is 1 - 5.

[0016] More preferably, in step S1, the pH value of the secondary amine derivatization reaction is 1 - 4.

[0017] More preferably, in step S1, the pH regulator for the secondary amine derivatization reaction includes at least one of hydrochloric acid and sulfuric acid.

[0018] Preferably, in step S1, before the secondary amine derivatization reaction, an internal standard is added to the water body to be measured.

[0019] More preferably, the internal standard is at least one of norfloxacin-D5 and ciprofloxacin-D8.

[0020] Preferably, in step S1, after the secondary amine derivatization reaction, extraction treatment is carried out.

[0021] More preferably, the extraction reagent for the extraction includes at least one of dichloromethane and chloroform.

[0022] Preferably, in step S1, the water body to be measured needs to be filtered before use, and the filtration treatment refers to filtration using a 0.2 - 0.5 μm filter membrane.

[0023] Preferably, in step S2, the carboxyl derivatization reagent is at least one of aromatic amines and aliphatic amines.

[0024] Preferably, the aromatic amine is at least one of aniline, 2-chloroaniline, 4-chloroaniline, 2,4-dichloroaniline, 3,4-dichloroaniline, and 2-phenylethylamine.

[0025] Preferably, the aliphatic amine is at least one of 3-aminotetrahydrothiophene, n-pentylamine, n-hexylamine, and n-heptylamine.

[0026] Preferably, the volume-to-mass ratio of the water body to be measured and the carboxyl derivatization reagent is 1 mL:(0.0002 - 0.8) g.

[0027] Preferably, in step S2, the temperature of the carboxyl derivatization reaction is 0 - 25 °C, and the time is 0.5 - 72 h.

[0028] Preferably, in step S2, the carboxyl derivatization reaction uses N,N'-dicyclohexylcarbodiimide (DCC) to activate the carboxyl group.

[0029] More preferably, the volume-to-mass ratio of the water body to be measured and N,N'-dicyclohexylcarbodiimide (DCC) is 1 mL:(0.0001 - 0.3) g.

[0030] In a second aspect, the present invention provides a method for detecting ciprofloxacin in a water body, comprising the following steps:

[0031] Using gas chromatography-tandem mass spectrometry (GC-MS) to detect the test solution containing ciprofloxacin derivative (CIP derivative) described in the first aspect.

[0032] Preferably, the chromatographic column of the gas chromatography is any one of DB-5MS, HP-5MS, and DB-5HT.

[0033] More preferably, the length of the DB-5MS is 30 m, the film thickness is 0.25 μm, and the inner diameter is 0.25 mm.

[0034] More preferably, the length of the HP-5MS is 30 m, the film thickness is 0.25 μm, and the inner diameter is 0.25 mm.

[0035] More preferably, the length of the DB-5HT is 30 m, the film thickness is 0.1 μm, and the inner diameter is 0.25 mm.

[0036] Preferably, the conditions of the gas chromatography are as follows:

[0037] Injection port temperature: 250 - 300 °C; carrier gas: helium (purity 99.999%); injection mode: splitless; chromatographic column flow rate: 0.6 - 1.5 mL / min; temperature programming: initial temperature 100 - 130 °C, rising to 300 - 320 °C at a rate of 10 - 20 °C / min, and holding for 3 - 8 min.

[0038] More preferably, the injection port temperature is 270 °C.

[0039] More preferably, the chromatographic column flow rate is 1.0 mL / min.

[0040] More preferably, the temperature rising program is an initial temperature of 100°C, rising to 300°C at a rate of 20°C / min and holding for 5 min.

[0041] Preferably, the conditions of the mass spectrometry are as follows:

[0042] Ion source: electron impact ion source; ion source temperature: 200 - 250°C; ionization energy: 70 eV; quadrupole temperature: 140 - 160°C; solvent delay: 3 - 8 min; acquisition mode: full scan mode (SCAN).

[0043] More preferably, the ion source temperature is 230°C.

[0044] More preferably, the quadrupole temperature is 150°C.

[0045] More preferably, the solvent delay is 5 min.

[0046] Preferably, the range of the full scan mode (SCAN) is 50 - 600 m / z.

[0047] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0048] The pretreatment method of ciprofloxacin in water established by the present invention through secondary amine derivatization and carboxyl derivatization of ciprofloxacin can obtain a target peak with a symmetric, sharp and non-tailing peak shape when used in gas chromatography - tandem mass spectrometry (GC - MS), and has a short determination time, and can elute within 10 min. At the same time, the detection method established relying on the pretreatment method of ciprofloxacin in water has a low detection limit, reaching the ng / L level, a high sample spiking recovery rate, and high precision and accuracy. Description of the Drawings

[0049] Figure 1 It is the chromatogram of CIP derivative 1 in Examples 1 - 5. In the figure, a is the chromatographic elution curve of CIP derivative 1 in Example 1, b is the chromatographic elution curve of CIP derivative 1 in Example 2, c is the chromatographic elution curve of CIP derivative 1 in Example 3, d is the chromatographic elution curve of CIP derivative 1 in Example 4, and e is the chromatographic elution curve of CIP derivative 1 in Example 5.

[0050] Figure 2 It is the chromatogram of CIP derivatives in Examples 1, 6 - 9. In the figure, a is the chromatographic elution curve of CIP derivative 1 in Example 1, b is the chromatographic elution curve of CIP derivative 2 in Example 6, c is the chromatographic elution curve of CIP derivative 3 in Example 7, d is the chromatographic elution curve of CIP derivative 4 in Example 8, and e is the chromatographic elution curve of CIP derivative 5 in Example 9.

[0051] Figure 3 Chromatogram of the CIP derivatives of Example 1 and 10 - 11. In the figure, a is the chromatographic elution curve of the CIP derivative 1 of Example 1, b is the chromatographic elution curve of the CIP derivative 1 of Example 10, and c is the chromatographic elution curve of the CIP derivative 1 of Example 11.

[0052] Figure 4 Chromatogram of the CIP derivatives of Example 1 and Comparative Examples 1 - 2. In the figure, a is the chromatographic elution curve of the CIP derivative 1 of Example 1, b is the chromatographic elution curve of the CIP derivative 6 of Comparative Example 1, and c is the chromatographic elution curve of the CIP derivative 7 of Comparative Example 2.

[0053] Figure 5 Chromatogram of the CIP derivative of Example 12. Detailed implementation mode

[0054] To better illustrate the purpose, technical solution and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0055] The reagents used in the present invention and their preparation methods are as follows:

[0056] Preparation of 10 mg / L ciprofloxacin (CIP) stock solution: Accurately weigh 10 mg of ciprofloxacin standard substance (accurate to 0.1 mg), dissolve it with methanol and make up the volume to 1 L volumetric flask to obtain 10 mg / L CIP stock solution, and store it in the dark at 4 °C in the refrigerator.

[0057] Preparation of 10 μg / L ciprofloxacin (CIP) intermediate stock solution: Accurately pipette 0.1 mL of 10 mg / L CIP stock solution into a 100 mL volumetric flask, and make up the volume with methanol to obtain 10 μg / L CIP intermediate stock solution, and store it in the dark at 4 °C in the refrigerator.

[0058] Preparation of a series of ciprofloxacin (CIP) working solutions: Gradually dilute the 10 μg / L CIP intermediate stock solution with methanol to obtain CIP working solutions of 0.1 ng / L, 0.5 ng / L, 1 ng / L, 5 ng / L, 10 ng / L, 20 ng / L, 50 ng / L, 100 ng / L, 200 ng / L, and store them in the dark at 4 °C in the refrigerator.

[0059] Preparation of 10 mg / L norfloxacin - D5 standard solution: Accurately weigh 10 mg of norfloxacin - D5 standard substance (accurate to 0.1 mg), dissolve it with methanol and make up the volume to 1 L volumetric flask to obtain 10 mg / L norfloxacin - D5 standard solution, and store it in the dark at 4 °C in the refrigerator.

[0060] Preparation of 5000 ng / L norfloxacin-D5 standard solution: Dilute 10 mg / L norfloxacin-D5 standard solution with methanol to 5000 ng / L to obtain 5000 ng / L norfloxacin-D5 standard solution, and store it in the refrigerator at 4°C in the dark.

[0061] Example 1

[0062] This example provides a pretreatment method for ciprofloxacin in water, including the following steps:

[0063] S1. Filter 50 ng / L ciprofloxacin (CIP) working solution with a filter equipped with a 0.22 μm PTFE membrane, take 10 mL, add 100 μL of 5000 ng / L norfloxacin-D5 standard solution (internal standard), adjust the pH of the system to pH = 2 with 2 mol / L hydrochloric acid, add 200 μL of 0.80 g / mL sodium nitrite solution, and carry out secondary amine derivatization reaction at 4°C for 30 min, then extract with 15 mL of dichloromethane to obtain a liquid containing the preliminary ciprofloxacin derivative 1.

[0064] S2. Add 0.18 g of 3-aminotetrahydrothiophene (carboxyl derivatization reagent) and 0.01 g of N,N'-dicyclohexylcarbodiimide (DCC) to the liquid containing the preliminary ciprofloxacin derivative 1, mix, and carry out carboxyl derivatization reaction at 15°C for 36 h to obtain a test solution containing ciprofloxacin derivative 1 (CIP derivative 1).

[0065] A detection method for ciprofloxacin in water includes the following steps:

[0066] First, filter the test solution containing ciprofloxacin derivative 1 (CIP derivative 1) with a filter equipped with a 0.22 μm PTFE membrane, and then detect the test solution containing ciprofloxacin derivative 1 (CIP derivative 1) by gas chromatography-tandem mass spectrometry (GC-MS);

[0067] The conditions of the gas chromatography are as follows:

[0068] Chromatographic column: DB-5MS (Agilent, length 30 m, film thickness 0.25 μm, inner diameter 0.25 mm); injection port temperature: 270°C; carrier gas: helium (purity 99.999%); injection mode: splitless; chromatographic column flow rate: 1.0 mL / min; temperature programming: initial temperature 100°C, heated to 300°C at a rate of 20°C / min, and held for 5 min;

[0069] The conditions of the mass spectrometry are as follows:

[0070] Ion source: Electron impact ion source; Ion source temperature: 230 °C; Ionization energy: 70 eV; Quadrupole temperature: 150 °C; Solvent delay: 5 min; Acquisition mode: Full scan mode (SCAN); Range of full scan mode (SCAN): 50 - 600 m / z.

[0071] Examples 2 - 5

[0072] Examples 2 - 5 provide pretreatment methods and detection methods for ciprofloxacin in different water bodies. The difference from Example 1 is that the pH value of the secondary amine derivatization reaction in step S1 is different, and the rest are the same as in Example 1. The specific details are shown in the following table:

[0073] Table 1 pH values of the secondary amine derivatization reaction in step S1 of Examples 1 - 5

[0074] pH value of the secondary amine derivatization reaction in step S1 Example 1 2 Example 2 1 Example 3 3 Example 4 4 Example 5 5

[0075] Examples 6 - 9

[0076] Examples 6 - 9 provide pretreatment methods and detection methods for ciprofloxacin in different water bodies. The difference from Example 1 is that the carboxyl derivatization reagents in step S2 are different, and the rest are the same as in Example 1. The specific details are shown in the following table:

[0077] Table 2 Carboxyl derivatization reagents in step S2 of Examples 1, 6 - 9

[0078]

[0079] Examples 10 - 11

[0080] Examples 10 - 11 provide pretreatment methods and detection methods for ciprofloxacin in different water bodies. The difference from Example 1 is that the types of chromatographic columns selected are different, and the rest are the same as in Example 1. The specific details are shown in the following table:

[0081] Table 3 Types of chromatographic columns of Examples 1, 10 - 11

[0082]

[0083] Example 12

[0084] This example provides a pretreatment method for ciprofloxacin in water bodies, including the following steps:

[0085] S1. Filter the water sample to be tested (taken from a reservoir) with a filter equipped with a 0.22 μm PTFE membrane. Take 10 mL, add 100 μL of 5000 ng / L norfloxacin-D5 standard solution (internal standard), adjust the pH of the system to pH = 2 with 2 mol / L hydrochloric acid, add 200 μL of 0.80 g / mL sodium nitrite solution, and carry out the secondary amine derivatization reaction at 4 °C for 30 min. Extract with 15 mL of dichloromethane to obtain a liquid containing the preliminary derivative 1 of ciprofloxacin.

[0086] S2. Add 0.18 g of 3-aminotetrahydrothiophene (carboxyl derivatization reagent) and 0.01 g of N,N'-dicyclohexylcarbodiimide (DCC) to the liquid containing the preliminary derivative 1 of ciprofloxacin, mix, and carry out the carboxyl derivatization reaction at 15 °C for 36 h to obtain the test solution containing ciprofloxacin derivative 1 (CIP derivative 1).

[0087] A method for detecting ciprofloxacin in water bodies, comprising the following steps:

[0088] First, filter the test solution containing ciprofloxacin derivative 1 (CIP derivative 1) with a filter equipped with a 0.22 μm PTFE membrane, and then detect the test solution containing ciprofloxacin derivative 1 (CIP derivative 1) by gas chromatography-tandem mass spectrometry (GC-MS);

[0089] The conditions of the gas chromatography are as follows:

[0090] Chromatographic column: DB-5MS (Agilent, length 30 m, film thickness 0.25 μm, inner diameter 0.25 mm); injection port temperature: 270 °C; carrier gas: helium (purity 99.999%); injection mode: splitless; chromatographic column flow rate: 1.0 mL / min; temperature programming: initial temperature 100 °C, heating at 20 °C / min to 300 °C, holding for 5 min;

[0091] The conditions of the mass spectrometry are as follows:

[0092] Ion source: electron impact ion source; ion source temperature: 230 °C; ionization energy: 70 eV; quadrupole temperature: 150 °C; solvent delay 5 min; acquisition mode: full scan mode (SCAN); range of full scan mode (SCAN): 50 - 600 m / z.

[0093] Comparative Example 1

[0094] This comparative example provides a pretreatment method for ciprofloxacin in water bodies, which is different from Example 1 in that only sodium nitrite is used for the secondary amine derivatization reaction without carrying out the carboxyl derivatization reaction. The specific steps are as follows:

[0095] Filter the 50 ng / L ciprofloxacin (CIP) working solution with a filter equipped with a 0.22 μm PTFE membrane. Take 10 mL, add 100 μL of 5000 ng / L norfloxacin-D5 standard solution (internal standard), adjust the pH of the system to pH = 2 with 2 mol / L hydrochloric acid, add 200 μL of 0.80 g / mL sodium nitrite solution, and carry out the secondary amine derivatization reaction at 4 °C for 30 min. Extract with 15 mL of dichloromethane to obtain the test solution containing ciprofloxacin derivative 6 (CIP derivative 6).

[0096] A method for detecting ciprofloxacin in water bodies includes the following steps:

[0097] First, filter the test solution containing ciprofloxacin derivative 6 (CIP derivative 6) with a filter equipped with a 0.22 μm PTFE membrane, and then detect the test solution containing ciprofloxacin derivative 6 (CIP derivative 6) by gas chromatography-tandem mass spectrometry (GC-MS);

[0098] The conditions of the gas chromatography are as follows:

[0099] Chromatographic column: DB-5MS (Agilent, length 30 m, film thickness 0.25 μm, inner diameter 0.25 mm); injection port temperature: 270 °C; carrier gas: helium (purity 99.999%); injection mode: splitless; chromatographic column flow rate: 1.0 mL / min; temperature programming: initial temperature 100 °C, rising to 300 °C at a rate of 20 °C / min and holding for 5 min;

[0100] The conditions of the mass spectrometry are as follows:

[0101] Ion source: electron impact ion source; ion source temperature: 230 °C; ionization energy: 70 eV; quadrupole temperature: 150 °C; solvent delay 5 min; acquisition mode: full scan mode (SCAN); range of full scan mode (SCAN): 50 - 600 m / z.

[0102] Comparative Example 2

[0103] This comparative example provides a pretreatment method for ciprofloxacin in water bodies, which is different from Example 1 in that only 3-aminotetrahydrothiophene (carboxyl derivatization reagent) is used for carboxyl derivatization reaction without secondary amine derivatization reaction, and specifically includes the following steps:

[0104] Filter the 50 ng / L ciprofloxacin (CIP) working solution with a filter equipped with a 0.22 μm PTFE membrane. Take 10 mL, add 100 μL of 5000 ng / L norfloxacin-D5 standard solution (internal standard), then add 0.18 g of 3-aminotetrahydrothiophene (carboxyl derivatization reagent) and 0.01 g of N,N'-dicyclohexylcarbodiimide (DCC), mix, and carry out the carboxyl derivatization reaction at 15 °C for 36 h to obtain a test solution containing ciprofloxacin derivative 7 (CIP derivative 7).

[0105] A method for detecting ciprofloxacin in water bodies includes the following steps:

[0106] First, filter the test solution containing ciprofloxacin derivative 7 (CIP derivative 7) with a filter equipped with a 0.22 μm PTFE membrane, and then use gas chromatography-tandem mass spectrometry (GC-MS) to detect the test solution containing ciprofloxacin derivative 7 (CIP derivative 7);

[0107] The conditions of the gas chromatography are as follows:

[0108] Chromatographic column: DB-5MS (Agilent, length 30 m, film thickness 0.25 μm, inner diameter 0.25 mm); injection port temperature: 270 °C; carrier gas: helium (purity 99.999%); injection mode: splitless; chromatographic column flow rate: 1.0 mL / min; temperature programming: initial temperature 100 °C, rising to 300 °C at a rate of 20 °C / min and holding for 5 min;

[0109] The conditions of the mass spectrometry are as follows:

[0110] Ion source: electron impact ion source; ion source temperature: 230 °C; ionization energy: 70 eV; quadrupole temperature: 150 °C; solvent delay 5 min; acquisition mode: full scan mode (SCAN); range of full scan mode (SCAN): 50 - 600 m / z.

[0111] Performance test

[0112] 1. Experimental results of gas chromatography-tandem mass spectrometry (GC-MS) for each example and comparative example

[0113] Figure 1 The chromatogram of CIP derivative 1 for Examples 1 - 5. In the figure, a is the chromatographic elution curve of CIP derivative 1 in Example 1, b is the chromatographic elution curve of CIP derivative 1 in Example 2, c is the chromatographic elution curve of CIP derivative 1 in Example 3, d is the chromatographic elution curve of CIP derivative 1 in Example 4, and e is the chromatographic elution curve of CIP derivative 1 in Example 5.

[0114] From Figure 1It can be seen that when the pH of the secondary amine derivatization reaction is 1 - 5, especially when the pH is 1 - 4, the chromatographic peak of CIP derivative 1 is symmetric, sharp, without tailing, and the retention time is 7.2 min. This indicates that the pretreatment method for ciprofloxacin in water established by the secondary amine derivatization and carboxyl derivatization of ciprofloxacin has a shorter determination time when used in gas chromatography - tandem mass spectrometry, and can have a good response signal for CIP derivative 1, and can detect ciprofloxacin well.

[0115] Figure 2 Chromatograms of CIP derivatives in Examples 1, 6 - 9. In the figure, a is the chromatographic elution curve of CIP derivative 1 in Example 1, b is the chromatographic elution curve of CIP derivative 2 in Example 6, c is the chromatographic elution curve of CIP derivative 3 in Example 7, d is the chromatographic elution curve of CIP derivative 4 in Example 8, and e is the chromatographic elution curve of CIP derivative 5 in Example 9.

[0116] From Figure 2 It can be seen that the pretreatment method for ciprofloxacin in water established by the secondary amine derivatization and carboxyl derivatization of ciprofloxacin has a shorter determination time when used in gas chromatography - tandem mass spectrometry, and can have a good response signal for CIP derivatives 1 - 5, and can detect ciprofloxacin well. Especially when the carboxyl derivatization reagent is 3 - aminotetrahydrothiophene, the chromatographic peak of GC - MS has a higher peak height, more symmetric, sharp and non - tailing shape, and can detect ciprofloxacin better.

[0117] Figure 3 Chromatograms of CIP derivatives in Examples 1, 10 - 11. In the figure, a is the chromatographic elution curve of CIP derivative 1 in Example 1, b is the chromatographic elution curve of CIP derivative 1 in Example 10, and c is the chromatographic elution curve of CIP derivative 1 in Example 11.

[0118] From Figure 3 It can be seen that compared with HP - 5MS and DB - 5HT, when using the DB - 5MS chromatographic column, the chromatographic peak of GC - MS has a higher peak height, more symmetric, sharp and non - tailing shape, and can detect ciprofloxacin better.

[0119] Figure 4 Chromatograms of CIP derivatives in Examples 1, Comparative Examples 1 - 2. In the figure, a is the chromatographic elution curve of CIP derivative 1 in Example 1, b is the chromatographic elution curve of CIP derivative 6 in Comparative Example 1, and c is the chromatographic elution curve of CIP derivative 7 in Comparative Example 2.

[0120] From Figure 4It can be seen that when ciprofloxacin is subjected to secondary amine derivatization and carboxyl derivatization, the chromatographic peak height of GC-MS is higher, the peak shape is more symmetrical, sharp and non-tailing, and ciprofloxacin can be detected better.

[0121] Figure 5 It is the chromatogram of the CIP derivative in Example 12.

[0122] From Figure 5 It can be seen that the pretreatment method and detection method of ciprofloxacin in the water body of the present invention have good signal response to the water body to be tested.

[0123] 2. Linear equation, detection limit and quantification limit test

[0124] The characteristic ions of the CIP derivative 1 in Example 1 are shown in Table 4:

[0125] Table 4 Characteristic ions of the CIP derivative 1 in Example 1

[0126] Qualitative ion (m / z) Quantitative ion (m / z) Example 1 439.2、410.2、307.0 307.0

[0127] According to the method of Example 1, standard curves were established using CIP working solutions of 0.1 ng / L, 0.5 ng / L, 1 ng / L, 5 ng / L, 10 ng / L, 20 ng / L, 50 ng / L, 100 ng / L, and 200 ng / L. Taking the mass concentration X (ng / L) of ciprofloxacin as the abscissa and the chromatographic peak area Y of the CIP derivative 1 as the ordinate, standard working curves were plotted. On this basis, the detection limit (LOD) of ciprofloxacin was determined with 3 times the signal-to-noise ratio (S / N), and the quantification limit (LOQ) of ciprofloxacin was determined with 10 times the signal-to-noise ratio (S / N). The experimental results are shown in the following table:

[0128] Table 5 Linear equation, detection limit and quantification limit of ciprofloxacin

[0129] Linear equation <![CDATA[Correlation coefficient r 2 > LOD (ng / L) LOQ (ng / L) Y = 116.085X + 95 0.9999 0.10 0.33

[0130] As can be seen from Table 5, in the range of 0.1 - 200 ng / L, the detection method established by the present invention using the pretreatment method of ciprofloxacin in the water body shows a good linear relationship with ciprofloxacin, and the correlation coefficient is 0.9999; moreover, the detection method of the present invention has high sensitivity, the detection limit is 0.10 ng / L, and the quantification limit is 0.33 ng / L.

[0131] 3. Accuracy and precision test

[0132] Recovery (accuracy) and precision tests were carried out through blank matrix spiking experiments. Referring to the detection method in Example 1, 0.1 mL of CIP working solutions with concentrations of 5 ng / L, 10 ng / L, and 50 ng / L were added respectively, and the spiked recoveries of ciprofloxacin were measured. At the same time, each spiking experiment was repeated in parallel 3 times (n = 3) for precision testing.

[0133] The results showed that the detection method established by the pretreatment method of ciprofloxacin in water body of the present invention had spiked recoveries of ciprofloxacin in the range of 95.9 - 104.2%, and the relative standard deviations of the spiked recoveries obtained by repeating each spiking experiment in parallel 3 times were all not greater than 1%, indicating that the detection method of ciprofloxacin in water body of the present invention had high accuracy and precision.

[0134] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for pre-treating ciprofloxacin in water, characterized in that: The steps include: S1. The water to be tested is subjected to secondary amine derivatization reaction with nitrite to obtain a liquid containing a preliminary derivative of ciprofloxacin; S2. Carrying out a carboxyl derivatization reaction on the liquid containing the preliminary derivative of ciprofloxacin with a carboxyl derivatization reagent to obtain a test liquid containing a ciprofloxacin derivative; In step S1, the pH value of the secondary amine derivatization reaction is 1-4; In step S2, the carboxyl derivatization reagent is 3-aminotetrahydrothiophene.

2. The pre-treatment method of ciprofloxacin in water according to claim 1, characterized in that: Including at least one of the following (1)-(4): (1) In step S1, the nitrite is at least one of sodium nitrite and potassium nitrite; (2) In step S1, the temperature of the secondary amine derivatization reaction is 0-10°C; (3) In step S2, the temperature of the carboxyl derivatization reaction is 0-25°C; (4) In step S2, the carboxyl group derivatization reaction uses N,N'-dicyclohexylcarbodiimide to activate the carboxyl group.

3. A method for detecting ciprofloxacin in water, characterized in that: The steps include: The test solution containing the ciprofloxacin derivative according to any one of claims 1 to 2 is detected by gas chromatography tandem mass spectrometry.

4. The method for detecting ciprofloxacin in water as claimed in claim 3, characterized in that: The chromatographic column of the gas chromatography is any one of DB-5MS, HP-5MS and DB-5HT.

5. The method for detecting ciprofloxacin in water as claimed in claim 3, characterized in that: The conditions of the gas chromatography are: Inlet temperature: 250-300℃; carrier gas: helium; injection mode: splitless; column flow: 0.6-1.5mL / min; heating program: initial temperature 100-130℃, increase to 300-320℃ at 10-20℃ / min, and maintain for 3-8min.

6. The method for detecting ciprofloxacin in water as claimed in claim 3, characterized in that: The conditions of the mass spectrometry are: Ion source: electron bombardment ion source; ion source temperature: 200-250°C; ionization energy: 70eV; quadrupole temperature: 140-160°C; solvent delay 3-8min; acquisition mode: full scan mode.

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