阅读说明：本技术 一种动物源食品中克霉唑残留的气相色谱-串联质谱检测方法 (Gas chromatography-tandem mass spectrometry detection method for clotrimazole residues in animal-derived food ) 是由 韩超 胡贝贞 叶明立 沈燕 付长春 魏云潇 王婷婷 于 2019-12-14 设计创作，主要内容包括：本发明公开了一种动物源食品中克霉唑残留的气相色谱-串联质谱检测方法。该方法为动物肌肉、脂肪和内脏样品中克霉唑残留使用环己烷/乙酸乙酯混合溶剂加速溶剂萃取、提取液经凝胶渗透色谱净化后采用气相色谱-串联质谱多反应监测模式下进行检测,同位素内标法定量。在优化的条件下,克霉唑在1.0～100μg/L范围内呈良好的线性关系,相关系数为0.9995,方法定量限为1.0μg/kg。方法平均回收率为76.5％～107.4％,相对标准偏差不大于6.2％。本方法提取效率高、净化效果好、灵敏度高、重复性好,可用于动物肌肉、脂肪和内脏中克霉唑残留量的测定。(The invention discloses a gas chromatography-tandem mass spectrometry detection method for clotrimazole residues in animal-derived food. The method comprises the steps of using a cyclohexane/ethyl acetate mixed solvent to accelerate solvent extraction of clotrimazole residues in animal muscle, fat and viscera samples, purifying an extracting solution through gel permeation chromatography, detecting in a gas chromatography-tandem mass spectrometry multi-reaction monitoring mode, and quantifying by an isotope internal standard method. Under the optimized condition, the clotrimazole has good linear relation in the range of 1.0-100 mug/L, the correlation coefficient is 0.9995, and the quantitative limit of the method is 1.0 mug/kg. The average recovery rate of the method is 76.5-107.4%, and the relative standard deviation is not more than 6.2%. The method has the advantages of high extraction efficiency, good purification effect, high sensitivity and good repeatability, and can be used for measuring the residual quantity of clotrimazole in animal muscles, fat and viscera.)

1. A gas chromatography-tandem mass spectrometry detection method for clotrimazole residues in animal-derived food is characterized by comprising the following steps:

step (1): extraction of animal muscle, fat and viscera samples: weighing 3.0g of sample, transferring the sample into a ceramic mortar, adding 60 mu L of d 5-clotrimazole standard solution with the concentration of 1.0 mu g/mL, adding 5g of 60-mesh diatomite, fully grinding, transferring the ground sample into a 10mL extraction pool, and performing accelerated solvent extraction under the following extraction conditions: the extraction solvent is cyclohexane and ethyl acetate, the volume ratio is 1:1, the extraction temperature is 100 ℃, the heating and static extraction are carried out for 5min, and the extraction solvent with the volume of 30 percent of the volume of the extraction pool is subjected to nitrogen purging for 60s to obtain the extraction liquid. Transferring the extract into a 50mL round-bottom flask, concentrating the extract to be less than 3mL by a rotary evaporator in a water bath at 35 ℃, transferring the residual liquid into a 10mL graduated centrifuge tube, and supplementing cyclohexane and ethyl acetate with the volume ratio of 1:1 to 3mL to prepare a liquid to be purified for later use.

Step (2): sample purification: the gel permeation chromatography conditions were as follows:

purifying the column: 500mm is multiplied by 10mm, 10g of Bio Beads-X3 packing is filled, and the height of a column bed is 32 cm;

mobile phase: cyclohexane and ethyl acetate in a volume ratio of 1:1, wherein the flow rate is 1.0 mL/min;

the sample quantitative ring is 1 mL; the volume of the pre-washing is 17 mL; the elution volume was 15 mL; the wash volume was 5 mL.

And (3) purifying 1mL of the solution to be purified prepared in the step (1) by a gel permeation apparatus according to the conditions, and collecting the eluent in a graduated centrifuge tube. Blowing nitrogen to be nearly dry in water bath at 45 ℃, taking 0.2mL of n-hexane saturated acetonitrile, carrying out vortex oscillation to dissolve residues, adding 0.5mL of n-hexane saturated acetonitrile, carrying out vortex oscillation and standing for layering, sucking out the acetonitrile layer in a 2mL sample injection vial, repeatedly adding 0.5mL of n-hexane saturated acetonitrile into a graduated centrifuge tube once, combining the acetonitrile layers, filtering by a 0.22 mu m filter membrane in the sample injection vial of a gas chromatography-tandem mass spectrometer to prepare a sample solution to be detected, and carrying out gas chromatography-tandem mass spectrometry.

And (3): preparation of a standard curve: taking 10mg of clotrimazole standard substance, dissolving with acetonitrile, transferring into a 100mL volumetric flask, and performing constant volume with acetonitrile to obtain 100 mu g/mL clotrimazole standard stock solution; taking 1mg of d 5-clotrimazole standard substance, dissolving with acetonitrile, transferring into a 10mL volumetric flask, and fixing the volume with the acetonitrile to obtain 100 mu g/mLd 5-clotrimazole standard stock solution; and respectively taking 0.1mL of 100 mu g/mL of clotrimazole and d 5-clotrimazole standard stock solution, diluting with acetonitrile to a constant volume of 10mL, and preparing 1.0 mu g/mL of clotrimazole and d 5-clotrimazole standard working solution. Preparation of working solution for calibration curve preparation: 1, 2, 5, 20, 50 and 100 mu L of 1.0 mu g/mL clotrimazole standard working solution is respectively added with 20 mu L of 1.0 mu g/mLd 5-clotrimazole solution, and then 979, 978, 975, 960, 930 and 880 mu L of acetonitrile to prepare a series of concentration standard curve solutions of 1, 2, 5, 20, 50 and 100 mu g/L, wherein the concentrations of the d 5-clotrimazole isotope internal standard solutions are 20 mu g/L.

And (4): and (3) detecting the sample solution to be detected: and (3) respectively injecting the sample solution to be detected prepared in the step (2) and the standard curve solution prepared in the step (3) on a gas chromatography-tandem mass spectrometer, and carrying out internal standard method quantitative calculation on quantitative ions according to the standard curve to obtain the concentration of clotrimazole in the sample solution to be detected, so as to obtain the content of clotrimazole in animal-derived food.

2. The method for detecting clotrimazole residue in animal-derived food according to claim 1, wherein the method comprises the following steps: in the purification mode in the step (2), the liquid to be purified is purified by a gel permeation apparatus to remove more than 80% of fat and other impurities, and then liquid-liquid extraction is adopted to remove the residual fat.

3. The method for detecting clotrimazole residue in animal-derived food according to claim 1, wherein the method comprises the following steps: the parameter conditions of the gas chromatography-tandem mass spectrometry in the step (4) are as follows:

a chromatographic column: HP-5ms, 30 m.times.0.25 mm.times.0.25 μm, temperature programmed:

Multiple reaction monitoring parameters of clotrimazole and d 5-clotrimazole

Technical Field

The invention relates to the field of food safety detection, relates to accelerated solvent extraction-gel permeation chromatography purification-gas chromatography-tandem mass spectrometry, and particularly relates to a gas chromatography-tandem mass spectrometry detection method for clotrimazole residues in animal-derived food.

Background

Clotrimazole is an imidazole antifungal drug, and studies show that the clotrimazole is used as an antifungal drug in animal breeding processes, so that the clotrimazole is remained in part of animal muscles, fat or internal organs. However, the 235 th bulletin of animal food veterinary drug residue limit of the Ministry of agriculture currently in China has no regulation on the use limit of such antifungal drugs including clotrimazole, and issued regulations and detection standards do not relate to clotrimazole. The newly issued GB 2763.1-2019 'maximum pesticide residue limit in national food Standard for food safety' also makes no provisions for the use limit of such antifungal agents including clotrimazole. In recent years, research on methods for detecting clotrimazole mainly focuses on determination of clotrimazole content in medicines, determination of residual quantity in human plasma and biological samples, and determination of residual quantity in environmental water and sludge. The above documents mainly adopt apparatuses such as a liquid chromatogram-fluorescence detector, a liquid chromatogram-tandem mass spectrum, a gas chromatogram and the like to measure clotrimazole, and the pretreatment mainly comprises dispersive solid-phase extraction, ultrasonic extraction, solid-phase extraction, dispersive liquid-phase microextraction and liquid-liquid extraction.

Compared with plant-derived food, the animal-derived food matrix has the problems of more complexity, high fat content and the like, and higher requirements on sample extraction, purification and detection are provided by analyzing the drug residues in the animal-derived food matrix.

An Accelerated solvent extraction (Accelerated solvent extraction) is the main pretreatment mode of the current solid and semisolid matrix samples, and compared with a Soxhlet extraction (Soxhlet extraction), the Accelerated solvent extraction (Accelerated solvent extraction) has the characteristics of rapidness, small solvent usage amount, high automation degree, good reproducibility, high extraction efficiency and higher safety.

Animal-derived food substrates are complex and high in fat content, and are often interfered by impurities, particularly some macromolecular substances, when the residual content of the drugs in the animal-derived food substrates is analyzed. In the invention, a Gel Permeation Chromatography (GPC) purification method is introduced to remove macromolecular impurities and fat components contained in the animal-derived food, so that the chromatographic interference of the macromolecular impurities and the fat on the analyte can be reduced, the deposition of the macromolecular impurities and the fat on a chromatographic injection port and a chromatographic column head can be avoided, and a chromatographic system is protected.

The existing detection method can only carry out qualitative and quantitative determination through retention time and response peak area through liquid chromatography and gas chromatography, and lacks substantial determination basis. Even after efficient purification and enrichment, the content of clotrimazole in animal-derived food is still very low, so subsequent analysis also needs efficient, sensitive and strong-universality separation and detection means. The chromatography-mass spectrometry combined technology integrating the chromatography super-strong separation capability, the mass spectrum high sensitivity and the high specific resolution capability is undoubtedly an ideal choice, and the gas chromatography-tandem mass spectrum (GC-MS/MS) technology has the remarkable advantages that other detection methods are unavailable: the kit has high sensitivity, high selectivity and high specificity, can accurately quantify and confirm known substances, and can efficiently identify and analyze unknown compounds qualitatively.

Disclosure of Invention

The invention provides a gas chromatography-tandem mass spectrometry detection method for clotrimazole residues in animal-derived food, which combines accelerated solvent extraction-gel permeation chromatography purification-gas chromatography-tandem mass spectrometry to determine clotrimazole in animal-derived food.

The purpose of the invention is realized by the following technical scheme: the invention provides a gas chromatography-tandem mass spectrometry detection method for clotrimazole residues in animal-derived food, which comprises the following steps:

step (1): extraction of animal muscle, fat and viscera samples: weighing 3.0g of sample, transferring the sample into a ceramic mortar, adding 60 mu L of d 5-clotrimazole standard solution with the concentration of 1.0 mu g/mL, adding 5g of 60-mesh diatomite, fully grinding, transferring the ground sample into a 10mL extraction pool, and performing accelerated solvent extraction under the following extraction conditions: the extraction solvent is cyclohexane and ethyl acetate, the volume ratio is 1:1, the extraction temperature is 100 ℃, the heating and static extraction are carried out for 5min, and the extraction solvent with the volume of 30 percent of the volume of the extraction pool is subjected to nitrogen purging for 60s to obtain the extraction liquid. Transferring the extract into a 50mL round-bottom flask, concentrating the extract to be less than 3mL by a rotary evaporator in a water bath at 35 ℃, transferring the residual liquid into a 10mL graduated centrifuge tube, and supplementing cyclohexane and ethyl acetate with the volume ratio of 1:1 to 3mL to prepare a liquid to be purified for later use.

Step (2): sample purification: the gel permeation chromatography conditions were as follows:

purifying the column: 500mm is multiplied by 10mm, 10g of Bio Beads-X3 packing is filled, and the height of a column bed is 32 cm;

mobile phase: cyclohexane and ethyl acetate in a volume ratio of 1:1, wherein the flow rate is 1.0 mL/min;

the sample quantitative ring is 1 mL; the volume of the pre-washing is 17 mL; the elution volume was 15 mL; the wash volume was 5 mL.

And (3) purifying 1mL of the solution to be purified prepared in the step (1) by a gel permeation apparatus according to the conditions, and collecting the eluent in a graduated centrifuge tube. Blowing nitrogen to be nearly dry in water bath at 45 ℃, taking 0.2mL of n-hexane saturated acetonitrile, carrying out vortex oscillation to dissolve residues, adding 0.5mL of n-hexane saturated acetonitrile, carrying out vortex oscillation and standing for layering, sucking out the acetonitrile layer in a 2mL sample injection vial, repeatedly adding 0.5mL of n-hexane saturated acetonitrile into a graduated centrifuge tube once, combining the acetonitrile layers, filtering by a 0.22 mu m filter membrane in the sample injection vial of a gas chromatography-tandem mass spectrometer to prepare a sample solution to be detected, and carrying out gas chromatography-tandem mass spectrometry.

And (3): preparation of a standard curve: taking 10mg of clotrimazole standard substance, dissolving with acetonitrile, transferring into a 100mL volumetric flask, and performing constant volume with acetonitrile to obtain 100 mu g/mL clotrimazole standard stock solution; taking 1mg of d 5-clotrimazole standard substance, dissolving with acetonitrile, transferring into a 10mL volumetric flask, and fixing the volume with the acetonitrile to obtain 100 mu g/mLd 5-clotrimazole standard stock solution; and respectively taking 0.1mL of 100 mu g/mL of clotrimazole and d 5-clotrimazole standard stock solution, diluting with acetonitrile to a constant volume of 10mL, and preparing 1.0 mu g/mL of clotrimazole and d 5-clotrimazole standard working solution. Preparation of working solution for calibration curve preparation: 1, 2, 5, 20, 50 and 100 mu L of 1.0 mu g/mL clotrimazole standard working solution is respectively added with 20 mu L of 1.0 mu g/mLd 5-clotrimazole solution, and then 979, 978, 975, 960, 930 and 880 mu L of acetonitrile to prepare a series of concentration standard curve solutions of 1, 2, 5, 20, 50 and 100 mu g/L, wherein the concentrations of the d 5-clotrimazole isotope internal standard solutions are 20 mu g/L.

And (4): and (3) detecting the sample solution to be detected: and (3) respectively injecting the sample solution to be detected prepared in the step (2) and the standard curve solution prepared in the step (3) on a gas chromatography-tandem mass spectrometer, and carrying out internal standard method quantitative calculation on quantitative ions according to the standard curve to obtain the concentration of clotrimazole in the sample solution to be detected, so as to obtain the content of clotrimazole in animal-derived food.

Further, in the purification mode in the step (2), the liquid to be purified is purified by a gel permeation apparatus to remove more than 80% of fat and other impurities, and then liquid-liquid extraction is adopted to remove the residual fat.

Further, the parameter conditions of the gas chromatography-tandem mass spectrometry in the step (4) are as follows:

a chromatographic column: HP-5ms, 30 m.times.0.25 mm.times.0.25 μm, temperature programmed:

the total running time is 17.33 min; sample introduction amount: 1 mu L of the solution; carrier gas: high-purity helium with the purity of more than or equal to 99.999 percent and the flow rate of 1.0 mL/min; sample inlet temperature: 240 ℃; collision gas: high-purity argon with the purity more than or equal to 99.999 percent; ion source temperature: 300 ℃; mass spectrometry transmission line temperature: 280 ℃; and (3) monitoring mode: multiple Reaction Monitoring (MRM), MRM ion pairs and voltages are shown in the following table, labeledAnd (4) quantifying ion pairs.

Multiple reaction monitoring parameters of clotrimazole and d 5-clotrimazole

The invention has the beneficial effects that: the invention extracts animal source food (animal muscle, fat and viscera) samples, purifies the extract, and finally concentrates and samples for detection. The first step of extraction: firstly, a sample is subjected to accelerated solvent extraction by cyclohexane/ethyl acetate (1:1, v/v); and a second step of purification: purifying the first-step extract by using a gel permeation apparatus to remove most of fat and other impurities, then removing the residual fat by using liquid-liquid extraction, and filtering by using a 0.22 mu m microporous filter membrane to obtain the purified liquid to be detected. The purified liquid to be detected cannot pollute a detection instrument. The method has the characteristics of rapid solvent extraction acceleration, small solvent usage amount, high automation degree, good reproducibility, high extraction efficiency and safety; the gel permeation chromatography purification method is used for removing macromolecular impurities and fat components contained in the animal-derived food, so that the chromatographic interference of the macromolecular impurities and the fat on analytes can be reduced, the deposition of the macromolecular impurities and the fat on a chromatographic sample inlet and a chromatographic column head can be avoided, and a chromatographic system is protected.

Secondly, the qualitative and quantitative detection and analysis of the residual clotrimazole content in animal-derived food (animal muscle, fat and viscera) is carried out by gas chromatography-tandem mass spectrometry. Firstly, preparing a group of step-shaped standard curve solutions, and then respectively injecting the standard curve solutions and the solution to be detected on a gas chromatography-tandem mass spectrometer. The retention time of a chromatographic peak appearing in the liquid to be detected is consistent with that of the standard working solution, the allowable deviation is less than +/-2.5%, the relative abundance of the mass spectrum qualitative ion pair corresponding to the chromatographic peak is consistent with that of the standard working solution with the equivalent concentration, and the deviation of the relative abundance does not exceed the specification, so that the clotrimazole contained in the liquid to be detected can be determined. In addition, in the quantitative analysis by mass spectrometry, there are two methods, an internal standard method and an external standard method, respectively. The internal standard method is to take a certain amount of isotope labeling substance as an internal standard substance, add the internal standard substance into a sample which is accurately weighed, and calculate the content of the component to be measured according to the mass ratio of the sample to be measured to the internal standard substance and the ratio of the corresponding chromatographic peak areas. The external standard method is a method of quantifying by comparing a response signal of a component to be measured in a sample with a reference substance which is a pure product of the component to be measured. The internal standard method is calculated by measuring the relative values of the peak areas of the internal standard substance and the measured component, so that errors caused by changes of operating conditions and the like are eliminated to a certain extent, and the measurement result is accurate. Although the external standard method is simple and convenient, the sampling amount requirement is very accurate, the external standard method needs to be strictly controlled to be carried out under the same operation condition with the standard substance, otherwise, analysis errors are caused, and an accurate measurement result cannot be obtained. Because the gas chromatography-tandem mass spectrometry generally has the influence of matrix effect, the external standard method is adopted for quantification, and the result is inaccurate. The invention adopts the isotope d5 to mark clotrimazole as the internal standard substance for quantification, and overcomes the problem of inaccurate quantification by an external standard method.

Drawings

FIG. 1 is a chemical structure of clotrimazole in an embodiment of the present invention; molecular formula C₂₂H₁₇N₂Cl。

FIG. 2 shows the extracted ion pair spectra of 20 μ g/L clotrimazole and D5-clotrimazole standard solution (A: the spectrum of ion pair 278.2 → 243.2; B: the spectrum of ion pair 278.2 → 165.1; C: the spectrum of ion pair 283.1 → 248.2; D: the spectrum of ion pair 283.1 → 169.6);

FIG. 3 is a second mass spectrum of clotrimazole and d 5-clotrimazole scanning ion pair in an embodiment of the present invention (A: clotrimazole; B: d 5-clotrimazole);

FIG. 4 is a standard operating curve for an embodiment of the present invention.

Detailed Description

The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.

The invention provides a method for detecting clotrimazole residue in animal-derived food by accelerated solvent extraction, gel permeation chromatography purification, gas chromatography and tandem mass spectrometry, which comprises the following steps.

Step (I) extraction of sample, as shown in the figure1 is clotrimazole with a chemical molecular formula of C₂₂H₁₇N₂Cl: weighing 3.0g of sample (animal muscle, fat and viscera) and transferring to a ceramic mortar, adding 60 μ L of 1.0 μ g/mL d 5-clotrimazole standard solution, adding 5g of 60-mesh diatomite and fully grinding, transferring the ground sample to a 10mL extraction cell for accelerated solvent extraction under the following extraction conditions: extracting solvent cyclohexane/ethyl acetate (1:1, v/v), heating at 100 deg.C for 5min, statically extracting for 5min, and purging 30% of extraction solvent nitrogen gas in the extraction tank for 60s to obtain extract. Transferring the extract into a 50mL round-bottom flask, concentrating the extract to be less than 3mL through a rotary evaporator under reduced pressure in a water bath at 35 ℃, transferring the residual liquid into a 10mL graduated centrifuge tube under the vacuum degree of 80-200mbar, and supplementing cyclohexane/ethyl acetate (1:1, v/v) to 3mL to prepare a liquid to be purified for later use.

And (2) purifying the sample: the gel permeation chromatography conditions were as follows: purifying the column: 500mm 10mm, 10g Bio Beads-X3 filler (neutral, porous polystyrene-divinylbenzene microspheres, rejection limit 400-; mobile phase: cyclohexane/ethyl acetate (1:1, v/v) at a flow rate of 1.0 mL/min; sample quantification loop: 1 mL; volume of pre-shower: 17 mL; elution volume: 15 mL; washing volume: 5 mL. And (5) taking 1mL of the solution to be purified in the step (I), purifying by a gel permeation apparatus according to the above conditions, and collecting the eluent in a graduated centrifuge tube. Blowing nitrogen to the collected eluent in a water bath at 45 ℃ until the eluent is nearly dry, wherein a sample with high fat content has a small amount of grease at the bottom of a centrifugal tube, taking 0.2mL of acetonitrile-saturated n-hexane to carry out vortex oscillation to dissolve the residue, then adding 0.5mL of acetonitrile-saturated n-hexane, carrying out vortex oscillation and standing for layering, sucking out the acetonitrile layer in a 2mL sample injection vial, repeatedly adding 0.5mL of acetonitrile-saturated n-hexane once, combining the acetonitrile layer, and filtering with a 0.22 mu m filter membrane in the sample injection vial for GC-MS/MS measurement. The liquid to be purified is purified by a gel permeation apparatus, so that more than 80% of fat and other impurities can be removed, and the residual fat can be removed by liquid-liquid extraction.

Step (three), preparation of a standard curve: taking 10mg of clotrimazole standard substance, dissolving with acetonitrile, transferring into a 100mL volumetric flask, fixing the volume to a scale with the acetonitrile, and preparing 100 mu g/mL clotrimazole standard stock solution; taking 1mg of d 5-clotrimazole standard substance, dissolving with acetonitrile, transferring into a 10mL volumetric flask, fixing the volume with the acetonitrile, preparing 100 mu g/mLd 5-clotrimazole standard stock solution, as shown in figure 2, 20 mu g/L of clotrimazole and d 5-clotrimazole standard solution extract ion pair spectrogram, having clean spectrogram background, no interference and high sensitivity. And respectively taking 0.1mL of 100 mu g/mL of clotrimazole and d 5-clotrimazole standard stock solution, diluting with acetonitrile to a constant volume of 10mL, and preparing 1.0 mu g/mL of clotrimazole and d 5-clotrimazole standard working solution. Preparation of calibration curve working solution: 1, 2, 5, 20, 50 and 100 mu L of 1.0 mu g/mL clotrimazole standard working solution are respectively added with 20 mu L of 1.0 mu g/mLd 5-clotrimazole standard working solution, and then 979, 978, 975, 960, 930 and 880 mu L of acetonitrile to prepare a series of concentration standard curve solutions of 1, 2, 5, 20, 50 and 100 mu g/L, wherein the concentration of the d 5-clotrimazole isotope internal standard solution is 20 mu g/L. As shown in FIG. 3, the second-order mass spectrum (A: clotrimazole; B: D5-clotrimazole) of the clotrimazole and D5-clotrimazole scanning ion pair is D5-clotrimazole, on the basis of the clotrimazole structural formula, 5 hydrogens (H) on the benzene ring are replaced by 5 deuterium (D, hydrogen isotope), so that the molecular weight is increased by 5, and the mass spectrum peak on the spectrum also has a corresponding molecular weight of 5.

Step (four), detecting the sample solution to be detected: and (3) respectively injecting the sample solution to be detected in the step (II) and the standard curve solution in the step (III) on a gas chromatography-tandem mass spectrometer, and carrying out quantitative calculation on quantitative ions by an internal standard method according to the standard curve to obtain the concentration of clotrimazole in the sample solution to be detected, so as to obtain the content of clotrimazole in animal-derived food.

The parameter conditions of the gas chromatography-tandem mass spectrometry are as follows:

a chromatographic column: HP-5ms, 30 m.times.0.25 mm.times.0.25 μm, temperature programmed:

the total running time is 17.33 min; sample introduction amount: 1 mu L of the solution; carrier gas: height ofPure helium with purity more than or equal to 99.999% and flow rate of 1.0 mL/min; sample inlet temperature: 240 ℃; collision gas: high-purity argon with the purity more than or equal to 99.999 percent; ion source temperature: 300 ℃; mass spectrometry transmission line temperature: 280 ℃; and (3) monitoring mode: multiple Reaction Monitoring (MRM), MRM ion pairs and voltages are shown in table 1, labeled as quantitative ion pairs.

TABLE 1 multiple reaction monitoring parameters of Clotrimazole and d 5-Clotrimazole

As shown in FIG. 4, which is a standard working curve in the embodiment of the present invention, the results show that clotrimazole has a good linear relationship in the range of 1.0-100 μ g/L, the correlation coefficient is 0.9995, the quantitative limit of the method is 1.0 μ g/kg, and the results are shown in Table 2.

TABLE 2 Linear equation, correlation coefficient, quantitative limits of Clotrimazole

Compound (I)	Linear equation of equations	Correlation coefficient	Limit of quantitation mu g/kg
				Clotrimazole	Y＝0.0189426+0.0474255X	0.9995	1.0

The limit of quantitation (LOQ) of the method was calculated as 10 times the signal-to-noise ratio (S/N) and the limit of quantitation of clotrimazole was 1.0. mu.g/kg, indicating that the method has a higher sensitivity.

Clotrimazole was added to the blank samples at concentrations of 1.0, 5.0, 10.0 μ g/kg, 3 levels, respectively, and the recovery and Relative Standard Deviation (RSD) results were listed in Table 3, for 6 replicates. As can be seen from Table 3, the method has an average recovery rate of 76.5-107.4% and a relative standard deviation of not more than 6.2%, and shows good recovery rate and precision. The method has the advantages of high extraction efficiency, good purification effect, high sensitivity and good repeatability, and can be used for measuring the residual quantity of clotrimazole in animal muscles, fat and viscera.

Table 3-recovery rate of addition, precision and limit of quantitation of clotrimazole (n ═ 6)

The present invention is not limited to the above embodiments, and those skilled in the art can implement the present invention in other embodiments according to the disclosure of the present invention, or make simple changes or modifications on the design structure and idea of the present invention, and fall into the protection scope of the present invention.