Method for detecting five novel pesticide residues in fruit and vegetable matrix by combining QuEChERS technology with gas chromatography-triple quadrupole mass spectrometry

Abstract

The invention relates to the technical field of food safety detection, and discloses a method for detecting five novel pesticide residues in a fruit and vegetable matrix by combining a QuEChERS technology with gas chromatography-triple quadrupole mass spectrometry. According to the method, a QuEChERS technology is combined with a gas chromatography-triple quadrupole mass spectrometry method to detect the content of the diflufenican, the ipfencarbazone, the oxathiazil, the cyclopyridazinate and the pethoxamid in the fruit and vegetable matrix. The method is simple, convenient, rapid and high in accuracy and precision, and provides technical support for daily detection of fruit and vegetable products; comprising 1, sample pretreatment: weighing a proper amount of a fruit and vegetable sample, and treating the fruit and vegetable sample with an extraction solvent, a water removal agent, an extraction salt and a cleaning agent to obtain a to-be-detected sample filter residue, 2, solution preparation: respectively preparing a required standard stock solution, a mixed standard working solution and a blank matrix standard solution, and 3, detecting the to-be-detected sample filter residue or / and the blank matrix standard solution.

Description

Technical Field

[0001] The present invention relates to the technical field of food safety detection. Specifically, it is a method for detecting 5 new types of pesticide residues in fruit and vegetable matrices by combining QuEChERS technology with gas chromatography-triple quadrupole mass spectrometry. Background Technique

[0002] China is rich in agricultural resources and has a profound history of agricultural civilization. It is a large agricultural country. As an important technical support for the agricultural system, pesticides play an important role in preventing and controlling crop pests and diseases and ensuring food security. The annual pesticide usage in China has exceeded 2 million tons. Pesticides can effectively increase the yield of agricultural products, but the improper use of pesticides will lead to an abnormal increase in the residue levels in agricultural products and the environment. Moreover, due to their stable chemical properties, they are not easily decomposed in the natural environment and will accumulate and enter the human body through the food chain. Long-term intake of pesticide compounds from different sources will produce a series of toxicities that affect human health, such as neurotoxicity, hepatotoxicity, and reproductive toxicity, and will also cause serious consequences of teratogenesis, carcinogenesis, and mutagenesis, posing a serious threat to human health. It is reported that there are approximately 385 million cases of accidental acute pesticide poisoning events globally every year, and approximately 44% of farmers die from pesticide poisoning. The problem of pesticide residues is becoming increasingly severe and has become an urgent problem to be solved in agricultural production. With the continuous advancement of globalization and the increasing frequency of international trade, countries have higher and higher requirements for the quality and safety of imported and exported foods. Pesticide residue detection technology not only has profound significance in ensuring food safety for people, but also can effectively promote the sustainable development of agriculture, ensure the smooth progress of international trade, and help break through a series of international trade technical barriers of pesticide residue standards and regulations for agricultural products formulated by other countries.

[0003] When detecting pesticide residues, due to the extremely low content of pesticides, complex sample matrices, and significant interference from impurities, pretreatment technology is of utmost importance in the entire detection process. The main pretreatment methods for detecting pesticide residues in fruit and vegetable products include solid-phase extraction, solid-phase microextraction, liquid-liquid extraction, QuEChERS method, etc. Among them, QuEChERS (Quick, Easy, Cheap, Effective, Rugged, Safe) technology mainly includes two steps: liquid-liquid extraction and dispersive solid-phase extraction. It provides more reliable results with less solvent, enables the recovery rates of various compounds to be between 70% and 120%, and can efficiently remove most interfering impurities in the matrix, achieving efficient pretreatment of samples. It has the advantages of being convenient, efficient, simple to operate, economical, and environmentally friendly, and has been widely used in the separation and enrichment of pesticides in the food pretreatment process. Liquid chromatography-tandem mass spectrometry (LC-MS / MS) and gas chromatography-tandem mass spectrometry (GC-MS / MS) are often used as detection methods in the analysis of pesticide residues due to their high sensitivity. Among them, gas chromatography-tandem mass spectrometry (GC-MS / MS) is completed by adsorbing pesticides, especially pesticides containing polar active groups. The heated injection port of the GC-MS / MS system has a protective effect on pesticides, which can prevent potential thermal degradation. At the same time, it also has advantages such as a wide measurement range, fast analysis speed, high quantitative accuracy, and strong anti-interference ability. The combination of QuEChERS pretreatment technology and chromatography-tandem mass spectrometry technology can make the detection of pesticide residues in fruits and vegetables more efficient and convenient.

[0004] Pethoxamid is a new type of chloroacetanilide herbicide, which is highly soluble in water (400 mg / L). It is mainly used for weed control in corn and soybean fields. It degrades through aerobic and anaerobic metabolism, with a half-life of 7 to 13 days. Residues can usually be detected in the topsoil layer. Pyrifluquinazon is a pymetrozine analog insecticide, which has a high killing effect on piercing-sucking mouthpart insects. It will seep into the aquatic environment through rainfall and surface runoff and persist in water, with a hydrolysis half-life of more than 3 months, indicating that it will accumulate in the aquatic environment and be toxic to aquatic organisms. Ipfencarbazone is a triazolinone herbicide developed by Kitakyo Chemical Industry Co., Ltd. in Japan, which has a high herbicidal effect on gramineous weeds in paddy fields. There are few relevant research reports on ipfencarbazone and flutianil at home and abroad, but some countries have maximum residue limit standards for them. For example, Japan stipulates that the maximum content of ipfencarbazone in rice is 0.05 mg / kg, and Canada stipulates that the content of flutianil in apples should be less than 0.15 mg / kg. Cyclopyrimorate is a new type of herbicide developed by Mitsui Chemicals Agro Co., Ltd., which is effective against various paddy weeds. Japan stipulates that its MRL value in rice is 0.01 mg / kg. There are no relevant regulations for these five pesticides in the national food safety standards of our country, but they are key detection targets for pesticide residues when exporting to the European Union, Japan and other countries. Therefore, establishing a detection method for them can effectively respond to international trade technical barriers and improve the competitiveness of our agricultural products in the international market. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for detecting 5 new pesticide residues in fruit and vegetable matrices by combining QuEChERS technology with gas chromatography-triple quadrupole mass spectrometry, and to adopt the method of combining QuEChERS technology with gas chromatography-triple quadrupole mass spectrometry to detect pyrifluquinazon, ipfencarbazone, flutianil, cyclopyrimorate and pethoxamid in fruit and vegetable matrices; this method is simple, fast, and has high accuracy and precision, providing technical support for the daily detection of fruit and vegetable products.

[0006] The present invention is achieved through the following technical solutions: A method for detecting 5 new pesticide residues in fruit and vegetable matrices by combining QuEChERS technology with gas chromatography-triple quadrupole mass spectrometry, including the following steps:

[0007] 1) Sample pretreatment: Weigh an appropriate amount of fruit and vegetable samples, and obtain the filter residue of the sample to be measured through treatment with an extraction solvent, a water remover, an extraction salt, and a purification agent.

[0008] 2) Solution preparation: Prepare the required standard stock solution, mixed standard working solution, and blank matrix standard solution respectively;

[0009] 3) Detect the filter residue of the sample to be tested and / or the blank matrix standard solution.

[0010] To further better implement the QuEChERS technology combined with gas chromatography-triple quadrupole mass spectrometry described in the present invention to establish a method for detecting 5 new types of pesticide residues in fruit and vegetable matrices, the following setting methods are particularly adopted: The step 1) includes the following specific steps:

[0011] 1.1) Weigh 10 g (accurate to 0.01 g) of fruit and vegetable samples and place them in a 50 ml centrifuge tube. Add 5 - 20 (such as 10) ml of extraction solvent (such as acetonitrile), oscillate for 5 min for extraction, add 4 g of water-removing agent (such as anhydrous magnesium sulfate) and 1 g of extraction salt (such as sodium chloride), oscillate for 10 min, mix well, and centrifuge at 8000 r / min for 5 min;

[0012] 1.2) After step 1.1), take 6 ml of the supernatant and place it in a 15 ml centrifuge tube. Add 0.9 g of water-removing agent (such as anhydrous magnesium sulfate), 50 - 250 mg of the first purification agent (such as 0.1 g of PSA), 0 - 200 mg of the second purification agent (such as 0.1 g of C18), and 0 - 20 mg of the third purification agent (such as 0.01 g of GCB), vortex and mix well for 5 min, centrifuge at 8000 r / min for 5 min, take 1 ml of the supernatant and filter it through a 0.22 μm organic filter membrane to obtain the filter residue of the sample to be tested.

[0013] To further better implement the QuEChERS technology combined with gas chromatography-triple quadrupole mass spectrometry described in the present invention to establish a method for detecting 5 new types of pesticide residues in fruit and vegetable matrices, the following setting methods are particularly adopted: In step 1.1), the extraction solvent is acetone, ethyl acetate, acetonitrile, or 1% acidic acetonitrile, and the dosage is 10 ml; the water-removing agent is anhydrous magnesium sulfate; the extraction salt is sodium chloride, sodium sulfate, sodium acetate, or sodium carbonate;

[0014] In step 1.2): the water-removing agent is anhydrous magnesium sulfate; the first purification agent is PSA, and the dosage is 0.1 g; the second purification agent is C18, and the dosage is 0.1 g; the third purification agent is GCB, and the dosage is 0.01 g.

[0015] To further better implement the QuEChERS technology combined with gas chromatography-triple quadrupole mass spectrometry described in the present invention to establish a method for detecting 5 new types of pesticide residues in fruit and vegetable matrices, the following setting methods are particularly adopted: In step 1.1), the extraction solvent is acetonitrile, and the extraction salt is sodium chloride.

[0016] To further better implement the QuEChERS technology combined with gas chromatography-triple quadrupole mass spectrometry for establishing a detection method for 5 new types of pesticide residues in fruit and vegetable matrices, the following setting methods are specifically adopted: The step 2) includes the following specific steps:

[0017] 2.1) Preparation of standard stock solution: Accurately weigh 0.001 g (accurate to 0.00001 g) of the standard sample of pyridazate in a 10 mL volumetric flask, add acetonitrile to dissolve it and dilute to the scale to prepare a standard stock solution of pyridazate at 100 μg / mL, and store it in the dark at -20 °C for future use; clethodim, pyflubumide, metazachlor, and flutriafol are all liquid standard samples with a mass concentration of 100 μg / mL, which are directly used as standard stock solutions and stored in the dark at -20 °C for future use, with a validity period of 6 months;

[0018] 2.2) Preparation of mixed standard working solution: Accurately measure 1 mL of each of the above five standard stock solutions respectively, dilute them with acetonitrile to prepare 10 mL of a mixed standard intermediate solution at 10 μg / mL, and store it in the refrigerator at -20 °C in the dark; measure an appropriate amount of the mixed standard intermediate solution, dilute it with acetonitrile to prepare a series of mixed standard working solutions with mass concentrations of 2, 10, 20, 50, 100, 200, and 500 μg / L for GC-MS / MS detection;

[0019] 2.3) Preparation of blank matrix standard solution: After pretreatment, a blank sample is obtained, and the mixed standard working solution is diluted with the blank sample to prepare a series of blank matrix standard solutions with concentrations of 2, 10, 20, 50, 100, 200, and 500 μg / L.

[0020] To further better implement the QuEChERS technology combined with gas chromatography-triple quadrupole mass spectrometry for establishing a detection method for 5 new types of pesticide residues in fruit and vegetable matrices, the following setting methods are specifically adopted: The blank sample is obtained through the following pretreatment method:

[0021] 2.3.1) Weigh 10 g (accurate to 0.01 g) of fruit and vegetable samples and place them in a 50 mL centrifuge tube, add 5 - 20 (such as 10) mL of extraction solvent (such as acetonitrile), oscillate for 5 min for extraction, add 4 g of water remover (such as anhydrous magnesium sulfate), 1 g of extraction salt (such as sodium chloride), oscillate for 10 min, mix well and centrifuge at 8000 r / min for 5 min;

[0022] 2.3.2) After step 2.3.1), take 6 ml of the supernatant and place it in a 15-ml centrifuge tube. Add 0.9 g of water remover (such as anhydrous magnesium sulfate), 50 - 250 mg of the first purifying agent (such as 0.1 g of PSA), 0 - 200 mg of the second purifying agent (such as 0.1 g of C18), and 0 - 20 mg of the third purifying agent (such as 0.01 g of GCB). Vortex and mix for 5 min, centrifuge at 8000 r / min for 5 min, take 1 ml of the supernatant and filter it through a 0.22-μm organic filter membrane to obtain a blank sample.

[0023] To further better implement the method for detecting 5 new types of pesticide residues in fruit and vegetable matrices by combining the QuEChERS technique with gas chromatography-triple quadrupole mass spectrometry of the present invention, the following setting methods are particularly adopted: In step 2.3.1), the extraction solvent is acetone, ethyl acetate, acetonitrile, or 1% acidic acetonitrile, and the dosage is 10 ml; the extraction salts are sodium chloride, sodium sulfate, sodium acetate, or sodium carbonate.

[0024] In step 2.3.2): The water remover is anhydrous magnesium sulfate; the first purifying agent is PSA, and the dosage is 0.1 g; the second purifying agent is C18, and the dosage is 0.1 g; the third purifying agent is GCB, and the dosage is 0.01 g.

[0025] To further better implement the method for detecting 5 new types of pesticide residues in fruit and vegetable matrices by combining the QuEChERS technique with gas chromatography-triple quadrupole mass spectrometry of the present invention, the following setting methods are particularly adopted: In step 2.3.1), the extraction solvent is acetonitrile, and the extraction salt is sodium chloride.

[0026] To further better implement the method for detecting 5 new types of pesticide residues in fruit and vegetable matrices by combining the QuEChERS technique with gas chromatography-triple quadrupole mass spectrometry of the present invention, the following setting methods are particularly adopted: When detecting the filter residue of the sample to be tested, use a GC-MS / MS-TQ8040 gas chromatography-mass spectrometry combined instrument for detection; and during the detection:

[0027] The chromatographic conditions are as follows:

[0028] SH-1701 (30 m × 0.25 mm, 0.25 μm) chromatographic column, SH-PolarWAX-MS (30 m × 0.25 mm, 0.25 μm) chromatographic column, or SH-I-5Sil MS capillary (30 m × 0.25 mm, 0.25 μm) chromatographic column; injection volume: 1 μL, splitless injection; carrier gas: helium; temperature programming: the initial temperature is 50°C and is held for 1 min, then heated at a rate of 25°C / min to 125°C, and then heated at a rate of 10°C / min to 300°C and held for 2 min; injection port temperature: 250°C.

[0029] The mass spectrometry conditions were as follows: ion source temperature: 230 °C; interface temperature: 250 °C; ionization method: electron impact (EI) source; ionization energy: 70 eV; detector voltage: 1.5 kV; scan mode: multiple reaction monitoring (MRM) mode; scan mass range: 50 - 550 m / z; solvent delay time: 3.5 min.

[0030] To better implement the method for detecting 5 new types of pesticide residues in fruit and vegetable matrices by combining the QuEChERS technique with gas chromatography-triple quadrupole mass spectrometry as described in the present invention, the following setting methods were particularly adopted: when detecting the filter residue of the sample to be tested, a GC-MS / MS-TQ8040 gas chromatography-mass spectrometry combined instrument was used for detection; and during the detection:

[0031] The chromatographic conditions were as follows:

[0032] SH-I-5Sil MS capillary column (30 m × 0.25 mm, 0.25 μm); injection volume: 1 μL, splitless injection; carrier gas: helium; temperature programming: initial temperature was maintained at 50 °C for 1 min, then increased to 125 °C at a rate of 25 °C / min, and then increased to 300 °C at a rate of 10 °C / min and maintained for 2 min; injection port temperature: 250 °C;

[0033] The mass spectrometry conditions were as follows: ion source temperature: 230 °C; interface temperature: 250 °C; ionization method: electron impact (EI) source; ionization energy: 70 eV; detector voltage: 1.5 kV; scan mode: multiple reaction monitoring (MRM) mode; scan mass range: 50 - 550 m / z; solvent delay time: 3.5 min.

[0034] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0035] The present invention provides a method for detecting pydiflumetofen, metconazole, flutriafol, pyridafol and clethodim in fruit and vegetable matrices by combining the QuEChERS technique with gas chromatography-triple quadrupole mass spectrometry; this method is simple, fast, with high accuracy and precision, and provides technical support for the daily detection of fruit and vegetable products.

[0036] The present invention can qualitatively and quantitatively analyze the residues of 5 pesticides such as clethodim in fruits and vegetables, and provides a new method for the detection of non-standard pesticide residues in China.

[0037] In the precision experiment of the present invention, the average recovery rates of the five information pesticide residues were 65.86% - 113.04%, and the precisions were 0.25% - 6.81%, all meeting the relevant limit standards for pesticide residues in fruits and vegetables in countries such as the European Union and Japan. Description of the Drawings

[0038] Figure 1 It is the MRM chromatogram of five compounds.

[0039] Figure 2 It is a schematic diagram of the influence of different extraction salts on the recovery rate of target compounds.

[0040] Figure 3 It is a schematic diagram of the influence of different dosages of extraction solvent on the recovery rate of target compounds.

[0041] Figure 4 It is a schematic diagram of the influence of different dosages of C18 on the recovery rate of target compounds.

[0042] Figure 5 It is a schematic diagram of the influence of different dosages of PSA on the recovery rate of target compounds.

[0043] Figure 6 It is a schematic diagram of the influence of different dosages of GCB on the recovery rate of target compounds. Detailed implementation manners

[0044] The present invention will be further described in detail below in conjunction with embodiments, but the implementation manners of the present invention are not limited thereto.

[0045] To make the purpose, technical solutions and advantages of the implementation manners of the present invention clearer, the technical solutions in the implementation manners of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the implementation manners of the present invention. Obviously, the described implementation manners are part of the implementation manners of the present invention, rather than all of the implementation manners. Based on the implementation manners in the present invention, all other implementation manners obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention. Therefore, the following detailed description of the implementation manners of the present invention provided in the drawings is not intended to limit the scope of the claimed present invention, but merely represents the selected implementation manners of the present invention.

[0046] For the present invention to achieve better technical effects, the instruments, materials and reagents involved include:

[0047] GC-MS / MS-TQ8040 gas chromatography-mass spectrometry (GC-MS) instrument, SH-I-5Sil MS capillary chromatographic column (30 m × 0.25 mm, 0.25 μm) (Shimadzu Corporation, Japan); 3H2RI type centrifuge, Huxi Company, China; Milli-Q Integarl type ultrapure water instrument, Millipore Corporation, USA; AE240 type electronic balance, Mettler Toledo Company, Switzerland; MTV-100 multi-tube vortex oscillator, HUXI Company, China; 0.22 μm nylon needle filter head (organic filter membrane, Tianjin Jinteng Experimental Equipment Co., Ltd.).

[0048] Acetonitrile, acetone (chromatographically pure, Fisher Scientific, USA); acetic acid (chromatographically pure, Sigma-Aldrich, Germany); N-propylethylenediamine (PSA), octadecylsilyl-bonded silica gel (C18), graphitized carbon black (GCB) (Shanghai Anpu Experimental Technology Co., Ltd.); anhydrous magnesium sulfate, sodium chloride, sodium sulfate, sodium carbonate, sodium acetate (analytical pure, Chengdu Kelong Chemical Co., Ltd.).

[0049] Pesticide standards: The mass concentrations of clethodim, pydiflumetofen, metazachlor, and fluopyram standards were 100 μg / mL, from Tianjin Aladdin Biochemical Technology Co., Ltd.; pyridafol was a solid reference material (10 mg, 96.7%, CAS: 499231-24-2), from LGC Labor Ltd. (see Table 1).

[0050] The fruit and vegetable samples (tomatoes, Chinese cabbages, oranges, apples, sugarcanes, etc.) used in the experiments were all from the samples submitted to the Chengdu Customs Technical Center for inspection.

[0051] Table 1 Basic information of five compounds

[0052]

[0053] When processing the data, Shimadzu Labsolutions 4.30 software was used for analysis and Origin 2024 software was used for plotting.

[0054] Example 1:

[0055] A method for detecting 5 new pesticides residues in fruit and vegetable matrices by combining QuEChERS technology with gas chromatography-triple quadrupole mass spectrometry was established. The method for detecting pydiflumetofen, metazachlor, fluopyram, pyridafol, and clethodim in fruit and vegetable matrices by combining QuEChERS technology with gas chromatography-triple quadrupole mass spectrometry; this method is simple, fast, with high accuracy and precision, providing technical support for the daily detection of fruit and vegetable products, including the following steps:

[0056] 1) Sample pretreatment: Weigh an appropriate amount of fruit and vegetable samples, and use an extraction solvent, a water remover, an extraction salt, and a purification agent to obtain the filter residue of the sample to be detected.

[0057] 2) Solution preparation: Prepare the required standard stock solution, mixed standard working solution, and blank matrix standard solution respectively.

[0058] 3) Detect the filter residue of the sample to be detected and / or the blank matrix standard solution.

[0059] Example 2:

[0060] This embodiment is a further optimization based on the above-mentioned embodiment. The same parts as the foregoing technical solution will not be elaborated here. Further, in order to better implement the QuEChERS technology combined with gas chromatography-triple quadrupole mass spectrometry for establishing a detection method for 5 new pesticide residues in fruit and vegetable matrices, the following setting methods are particularly adopted: Step 1) includes the following specific steps:

[0061] 1.1) Weigh 10 g (accurate to 0.01 g) of fruit and vegetable samples and place them in a 50 ml centrifuge tube. Add 5 - 20 (such as 10) ml of extraction solvent (such as acetonitrile), oscillate (preferably using an MTV-100 multi-tube vortex oscillator) for 5 min for extraction. Add 4 g of water remover (such as anhydrous magnesium sulfate) and 1 g of extraction salt (such as sodium chloride), and oscillate (preferably using an MTV-100 multi-tube vortex oscillator) for 10 min. After mixing evenly, centrifuge at 8000 r / min (preferably using a 3H2RI type centrifuge) for 5 min;

[0062] 1.2) After step 1.1), take 6 ml of the supernatant and place it in a 15 ml centrifuge tube. Add 0.9 g of water remover (such as anhydrous magnesium sulfate), 50 - 250 mg of the first purification agent (such as 0.1 g of PSA), 0 - 200 mg of the second purification agent (such as 0.1 g of C18), and 0 - 20 mg of the third purification agent (such as 0.01 g of GCB). Vortex and mix evenly (preferably using an MTV-100 multi-tube vortex oscillator) for 5 min, centrifuge at 8000 r / min for 5 min, and take 1 ml of the supernatant to pass through a 0.22 μm organic filter membrane (0.22 μm nylon needle filter) to obtain the filter residue of the sample to be tested.

[0063] Example 3:

[0064] This embodiment is a further optimization based on any of the above embodiments. The same parts as the foregoing technical solution will not be elaborated here. Further, in order to better implement the QuEChERS technology combined with gas chromatography-triple quadrupole mass spectrometry for establishing a detection method for 5 new pesticide residues in fruit and vegetable matrices, the following setting methods are particularly adopted: In step 1.1), the extraction solvent is acetone, ethyl acetate, acetonitrile or 1% acidic acetonitrile, and the dosage is 10 ml; the water remover is anhydrous magnesium sulfate; the extraction salt is sodium chloride, sodium sulfate, sodium acetate or sodium carbonate;

[0065] In step 1.2): the water remover is anhydrous magnesium sulfate; the first purification agent is PSA, and the dosage is 0.1 g; the second purification agent is C18, and the dosage is 0.1 g; the third purification agent is GCB, and the dosage is 0.01 g.

[0066] Example 4:

[0067] This embodiment is a further optimization based on any of the above embodiments. The same parts as the foregoing technical solutions will not be described herein again. Further, to better implement the QuEChERS technology combined with gas chromatography-triple quadrupole mass spectrometry for establishing a method for detecting 5 new pesticide residues in fruit and vegetable matrices, the following setting method is particularly adopted: In the step 1.1), the extraction solvent is acetonitrile and the extraction salt is sodium chloride.

[0068] To achieve better detection effects, the following optimizations are made to the pretreatment conditions:

[0069] (1) Optimization of the type of extraction salt:

[0070] The water content in the fruit and vegetable matrix is relatively high. Anhydrous MgSO4 can be used as a water remover to remove the water in the sample during the pretreatment process, and it has little impact on the pesticide itself. Adding salts such as NaCl will produce a salting-out effect, which can effectively reduce the solubility of the target compound in the aqueous phase and enrich it in the organic phase, thereby improving the extraction efficiency. During the R & D stage, when it was determined that 4 g of anhydrous magnesium sulfate, the water remover, was used in the present invention, the extraction effects of four extraction salts, namely sodium chloride, sodium sulfate, sodium acetate, and sodium carbonate, were compared respectively. As Figure 2 shown, the results show that when sodium chloride is used for extraction, the recoveries of the five target compounds (fluopyram, triaziflam, flutriafol, pyridafol, and clethodim) are between 80% and 115%. The data are relatively concentrated, and only the recovery of pyridafol is lower than that when other extraction salts are used. The recoveries of the other four target compounds are higher than those of the remaining salts. Therefore, the present invention preferably selects sodium chloride as the extraction salt.

[0071] (2) Optimization of the type of extraction solvent:

[0072] During the sample pretreatment process, the selection of the extraction solvent is crucial. Choosing a suitable extraction solvent can effectively reduce the interference of impurities and thus improve the recovery rate of compounds. In the R & D stage, the extraction solvents used in the detection of pesticide residues in fruit and vegetable matrices in this invention include acetone, ethyl acetate, acetonitrile, acidic acetonitrile, etc. Among them, acetone belongs to a polar solvent, is miscible with water, and easily extracts some pigments and oils in the matrix, which will cause a certain degree of interference to the detection results. Ethyl acetate belongs to a weakly polar solvent, is suitable for extracting macromolecular lipids and waxes, but is not suitable for extracting saccharide substances, and has certain limitations in fruit and vegetable matrices. Acetonitrile is the most widely used extraction solvent in the detection and analysis of agricultural and veterinary drug residues. It has high extraction efficiency, few interfering impurities, strong solubility and good stability. Many compounds have good extraction efficiency when using acidic acetonitrile. Therefore, this invention further experimentally compared the extraction efficiencies when acetonitrile, 1% acetic acid acetonitrile and acetone were used as extraction solvents (as shown in Table 3). The results showed that when acetonitrile was used as the extraction solvent, the recovery rates of five compounds (pyriprole, metazachlor, flutriafol, pyridate and clethodim) were all between 60% and 120%, meeting the requirements of the recovery rate in the national food safety standard of China "GBT27404 - 2008 Food Physical and Chemical Inspection", while only three compounds met the standard when using acetone and 1% acetic acid acetonitrile. Therefore, this invention further preferably selects acetonitrile as the extraction solvent in the pretreatment process of this method.

[0073] Table 3 Influence of extraction solvent type on recovery rate

[0074]

[0075] (III) Optimization of extraction solvent dosage:

[0076] The amount of extraction solvent used is also an important indicator affecting the extraction efficiency. Selecting an appropriate amount can not only completely extract the target compound, but also avoid environmental pollution caused by solvent waste. Therefore, in the R & D stage of the present invention, the recoveries of various substances were further investigated when 5 ml, 10 ml, 15 ml, and 20 ml of acetonitrile were added for extraction respectively. Each addition level was run in triplicate, and the spiked amount for each sample was 7 μg / L. The pretreatment steps were carried out according to the following method: First, weigh 10 g (accurate to 0.01 g) of the sample and place it in a 50 ml centrifuge tube, add 10 ml of acetonitrile, shake for 5 min for extraction, add 4 g of anhydrous magnesium sulfate and 1 g of sodium chloride, shake for 10 min, and after mixing, centrifuge at 8000 r / min for 5 min. Then, take 6 ml of the supernatant and transfer it to a 15 ml centrifuge tube, add 0.9 g of anhydrous magnesium sulfate, 0.15 g of PSA, 0.15 g of C18, and 0.015 g of GCB, vortex and mix for 5 min, centrifuge at 8000 r / min for 5 min, take 1 ml of the supernatant and filter it through a 0.22 μm organic filter membrane to obtain the required sample. When 5 ml was added, since the addition amount was small, the target compound could not be fully extracted, and the subsequent supernatant was not easy to collect. Therefore, the case of adding 5 ml of acetonitrile was not considered. The results are as Figure 3 shown. Except for pydiflumetofen, the recoveries of the other four substances gradually decreased with the increase in the amount of extraction solvent added. The recovery rate was the highest when 10 ml of acetonitrile was used for extraction. The recovery rate of pydiflumetofen was the highest when 15 ml was used, and the recovery rate was the second highest when 10 ml was used. Therefore, in order to save consumables and avoid waste, the present invention finally determined to select 10 ml of acetonitrile as the amount of extraction solvent for extraction.

[0077] (IV) Optimization of the amount of purifying agent:

[0078] A. Optimization of the amount of C18:

[0079] In the process of detecting pesticide residues, sample purification can remove some impurities, reduce the interference of the matrix itself on the detection, and at the same time can protect the instruments and consumables to the greatest extent. It is an indispensable step. There are many types of impurities in plant-derived samples, such as sugars, proteins, amino acids, pigments, etc. Some impurities will precipitate during the extraction process with acetonitrile, but other impurities will also be extracted at the same time. The QuEChERS technology is mainly based on solid-phase microextraction. In the pretreatment and purification process, four purification materials, anhydrous magnesium sulfate, C18, PSA, and GCB, are used to remove impurities in the sample and reduce matrix interference. The water contained in the matrix will cover the ammonia sites on PSA during the purification process, resulting in no adsorption effect of PSA. Therefore, anhydrous MgSO4 needs to be added for water removal. Anhydrous MgSO4 has the characteristics of small particle size and good water absorption capacity. At the same time, it will release heat during the water absorption process, which is beneficial to improving the extraction efficiency. In order to obtain the optimal purification effect and extraction recovery rate, during the research and development stage of the present invention, on the premise of adding 900 mg of anhydrous magnesium sulfate, the recovery rates of target compounds were investigated when different amounts of C18 (0 mg, 50 mg, 100 mg, 150 mg, 200 mg) were added. From Figure 4 It can be seen that when 50 mg and 200 mg of C18 are added, the average recovery rate of fluopyram is lower than 60%, which does not meet the regulations on the recovery rate in the national food safety standard of China, "GBT 27404-2008 Food Physical and Chemical Inspection". When the addition amount is 100 mg, the purification effect and average recovery rate of the five compounds in the fruit and vegetable matrix reach the optimum. Therefore, the present invention finally selects to add 100 mg of C18 as the dosage of the second purification agent.

[0080] B. Optimization of PSA dosage:

[0081] PSA is a weak anion exchange adsorbent that can effectively remove impurities such as fatty acids, carbohydrates, and phenols in the matrix. To explore the optimal dosage, the present invention set five levels of PSA addition amounts, namely 50 mg, 100 mg, 150 mg, 200 mg, and 250 mg. The results are as Figure 5 shown. The recovery rates of clethodim, pymetrozine, and pyridafol are not sensitive to the addition amount of PSA, and the recovery rates change little when different dosages are used. The average recovery rate of triaziflam gradually decreases with the increase of the PSA addition amount, and the recovery rate is the highest when 50 mg is added. The recovery rate of fluopyram is the highest when 100 mg of PSA is added, followed by 150 mg, and the recovery rate is lower than 60% when 200 mg is added. Therefore, in consideration of the recovery rate and in order to save consumables, 100 mg of PSA is selected as the dosage of the first purification agent.

[0082] C. Optimization of GCB dosage:

[0083] GCB is often used as a weakly polar or non-polar adsorbent to remove hydrophobic compounds such as pigments and sterols in samples, and has a good decolorization effect. The present invention explored the recovery rates at five GCB addition levels: 0 mg, 5 mg, 10 mg, 15 mg, and 20 mg. From Figure 6 It can be seen that the recovery rate when using GCB is higher than that without adding GCB. This is because GCB can effectively remove pigments such as steroids and chlorophyll in fruit and vegetable samples to reduce the influence of matrix impurities on the recovery rate. When adding 10 mg, the average recovery rate of the five target compounds reaches the highest, and then the recovery rate gradually decreases with the increase of the addition amount. This is because GCB has a strong adsorption effect on pesticides containing aromatic rings and having a certain symmetrical structure. The more GCB is added, the stronger the adsorption effect on pesticides, and the lower the recovery rate will be. Therefore, the present invention finally selects to add 10 mg of GCB as the dosage of the third purifying agent.

[0084] Example 5:

[0085] This example is further optimized on the basis of any of the above examples. The same parts as the foregoing technical solutions will not be described herein again. Further, in order to better implement the QuEChERS technology combined with gas chromatography-triple quadrupole mass spectrometry method to establish a detection method for 5 new pesticide residues in fruit and vegetable matrices, the following specific settings are particularly adopted: Step 2) includes the following specific steps:

[0086] 2.1) Preparation of standard stock solution: Accurately weigh 0.001 g (accurate to 0.00001 g) of the standard sample of pyraclonil in a 10 mL volumetric flask, add acetonitrile to dissolve it and dilute to the mark to prepare a standard stock solution of pyraclonil at 100 μg / mL, and store it in the dark at -20 °C for later use; Clethodim, pymetrozine, metazachlor, and flutianil are all liquid standard samples with a mass concentration of 100 μg / mL, which are directly used as standard stock solutions and stored in the dark at -20 °C for later use, with a validity period of 6 months;

[0087] 2.2) Preparation of mixed standard working solution: Accurately measure 1 mL of each of the above five standard stock solutions respectively, and dilute them with acetonitrile to prepare 10 mL of a mixed standard intermediate solution at 10 μg / mL, and store it in the refrigerator at -20 °C in the dark; Measure an appropriate amount of the mixed standard intermediate solution and dilute it with acetonitrile to prepare a series of mixed standard working solutions with mass concentrations of 2, 10, 20, 50, 100, 200, and 500 μg / L for GC-MS / MS detection;

[0088] 2.3) Preparation of blank matrix standard solution: After pretreatment, a blank sample is obtained, and the mixed standard working solution is diluted with the blank sample to prepare a series of blank matrix standard solutions with concentrations of 2, 10, 20, 50, 100, 200, and 500 μg / L.

[0089] Example 6:

[0090] This example is further optimized on the basis of any of the above examples. The same parts as the foregoing technical solutions will not be described herein again. Further, in order to better implement the QuEChERS technology combined with gas chromatography-triple quadrupole mass spectrometry to establish a method for detecting 5 new types of pesticide residues in fruit and vegetable matrices, the following settings are particularly adopted: The blank sample is obtained through the following pretreatment method:

[0091] 2.3.1) Weigh 10 g (accurate to 0.01 g) of fruit and vegetable samples and place them in a 50 ml centrifuge tube. Add 5 - 20 (such as 10) ml of extraction solvent (such as acetonitrile), oscillate for 5 min for extraction, add 4 g of water remover (such as anhydrous magnesium sulfate), 1 g of extraction salt (such as sodium chloride), and oscillate for 10 min. After mixing evenly, centrifuge at 8000 r / min for 5 min;

[0092] 2.3.2) After step 2.3.1), take 6 ml of the supernatant and place it in a 15 ml centrifuge tube. Add 0.9 g of water remover (such as anhydrous magnesium sulfate), 50 - 250 mg of the first purification agent (such as 0.1 g of PSA), 0 - 200 mg of the second purification agent (such as 0.1 g of C18), and 0 - 20 mg of the third purification agent (such as 0.01 g of GCB), vortex and mix evenly for 5 min, centrifuge at 8000 r / min for 5 min, and take 1 ml of the supernatant and pass it through a 0.22 μm organic filter membrane to obtain the blank sample.

[0093] Example 7:

[0094] This example is further optimized on the basis of any of the above examples. The same parts as the foregoing technical solutions will not be described herein again. Further, in order to better implement the QuEChERS technology combined with gas chromatography-triple quadrupole mass spectrometry to establish a method for detecting 5 new types of pesticide residues in fruit and vegetable matrices, the following settings are particularly adopted: In step 2.3.1), the extraction solvent is acetone, ethyl acetate, acetonitrile or 1% acidic acetonitrile, and the dosage is 10 ml; the extraction salt is sodium chloride, sodium sulfate, sodium acetate or sodium carbonate;

[0095] In step 2.3.2): The water remover is anhydrous magnesium sulfate; the first purification agent is PSA, and the dosage is 0.1 g; the second purification agent is C18, and the dosage is 0.1 g; the third purification agent is GCB, and the dosage is 0.01 g.

[0096] Example 8:

[0097] This embodiment is a further optimization based on any of the above embodiments. The same parts as the foregoing technical solutions will not be described herein again. To better implement the QuEChERS technology combined with gas chromatography-triple quadrupole mass spectrometry for establishing a method for detecting 5 new types of pesticide residues in fruit and vegetable matrices, the following settings are specifically adopted: In the step 2.3.1), the extraction solvent is acetonitrile and the extraction salt is sodium chloride.

[0098] Example 9:

[0099] This embodiment is a further optimization based on any of the above embodiments. The same parts as the foregoing technical solutions will not be described herein again. To better implement the QuEChERS technology combined with gas chromatography-triple quadrupole mass spectrometry for establishing a method for detecting 5 new types of pesticide residues in fruit and vegetable matrices, the following settings are specifically adopted: When detecting the filter residue of the sample to be tested, a GC-MS / MS-TQ8040 gas chromatography-mass spectrometry combined instrument is used for detection; and during the detection:

[0100] The chromatographic conditions are as follows:

[0101] SH-1701 (30 m × 0.25 mm, 0.25 μm) chromatographic column, SH-PolarWAX-MS (30 m × 0.25 mm, 0.25 μm) chromatographic column or SH-I-5Sil MS capillary (30 m × 0.25 mm, 0.25 μm) chromatographic column; injection volume: 1 μL, splitless injection; carrier gas: helium; temperature programming: the initial temperature is maintained at 50 °C for 1 min, then increased to 125 °C at a rate of 25 °C / min, and then increased to 300 °C at a rate of 10 °C / min and maintained for 2 min; injection port temperature: 250 °C;

[0102] The mass spectrometry conditions are as follows: ion source temperature: 230 °C; interface temperature: 250 °C; ionization mode: electron impact (EI) source; ionization energy: 70 eV; detector voltage: 1.5 kV; scan mode: multiple reaction monitoring (MRM) mode; scan mass range: 50 - 550 m / z; solvent delay time: 3.5 min.

[0103] Example 10:

[0104] This embodiment is a further optimization based on any of the above embodiments. The same parts as the foregoing technical solutions will not be described herein again. To better implement the QuEChERS technology combined with gas chromatography-triple quadrupole mass spectrometry for establishing a method for detecting 5 new types of pesticide residues in fruit and vegetable matrices, the following settings are specifically adopted: When detecting the filter residue of the sample to be tested, a GC-MS / MS-TQ8040 gas chromatography-mass spectrometry combined instrument is used for detection; and during the detection:

[0105] The chromatographic conditions are as follows:

[0106] SH-I-5Sil MS capillary column (30 m × 0.25 mm, 0.25 μm); injection volume: 1 μL, splitless injection; carrier gas: helium; temperature programming: initial temperature is maintained at 50 °C for 1 min, then increased to 125 °C at a rate of 25 °C / min, and then increased to 300 °C at a rate of 10 °C / min and held for 2 min; injection port temperature: 250 °C;

[0107] The mass spectrometry conditions are as follows: ion source temperature: 230 °C; interface temperature: 250 °C; ionization mode: electron impact (EI) source; ionization energy: 70 eV; detector voltage: 1.5 kV; scan mode: multiple reaction monitoring (MRM) mode; scan mass range: 50 - 550 m / z; solvent delay time: 3.5 min.

[0108] To obtain better detection results, the present invention optimizes the chromatographic and mass spectrometry methods:

[0109] Optimization of the chromatographic column:

[0110] During the R & D stage, the peak elution situations of five compounds (pyriofenozide, metazachlor, fluopyram, pyridate, and clethodim) on three chromatographic columns, namely SH-1701 (30 m × 0.25 mm, 0.25 μm), SH-PolarWAX-MS (30 m × 0.25 mm, 0.25 μm), and SH-I-5Sil MS capillary column (30 m × 0.25 mm, 0.25 μm), were compared. The results show that there is basically no peak elution on the SH-PolarWAX-MS chromatographic column and the target compounds cannot be detected. On the SH-1701 chromatographic column, although the target compounds elute, the response values are relatively low and there are many impurity peaks. However, when using the SH-I-5Sil MS capillary column, the five compounds are completely separated, with good peak shapes and relatively high response values. Therefore, the present invention selects the SH-I-5Sil MS capillary column as the analytical column.

[0111] Optimization of the mass spectrometry conditions:

[0112] Take a certain amount of standard stock solution and dilute it with acetonitrile into single pesticide substances at 10 μg / mL respectively. Chromatographic column: SH-I-5Sil MS capillary column (30 m × 0.25 mm, 0.25 μm); injection volume: 1 μL, splitless injection, carrier gas: helium; temperature programming: initial temperature is maintained at 50 °C for 1 min, then raised to 125 °C at a rate of 25 °C / min, and then raised to 300 °C at a rate of 10 °C / min and maintained for 2 min; injection port temperature: 250 °C. Under these chromatographic conditions, perform full scan mode analysis within m / z 50 - 550. For each substance, select one quantitative ion and two qualitative ions with large mass-to-charge ratio and high corresponding intensity. According to the retention time and mass spectrum of each target compound, optimize the parent ion, daughter ion and collision energy of the target compound in the multiple reaction monitoring mode (MRM), and finally establish a detection method. The optimized results of the mass spectrometry conditions for the five pesticide substances are shown in Table 2, and the MRM spectra are shown in Figure 1 , Figure 1 in which, 1 is pronamide, 2 is pymetrozine, 3 is metconazole, 4 is flutriafol, and 5 is pyridazinone.

[0113] Table 2 Mass spectrometry parameters of five compounds

[0114]

[0115] Based on the above embodiments, the present invention conducts the following various analyses and verifications:

[0116] 1. Investigation of matrix effect:

[0117] Matrix effect is a very common phenomenon in the analysis of pesticide residues in agricultural products. Matrix effect evaluation is required during the research of pesticide residue analysis methods to evaluate the applicability of the method. Matrix effect (ME%) = (slope of matrix calibration curve / slope of solvent calibration curve - 1) × 100%. When ME = 0, it indicates no matrix effect; |ME| < 20% is weak matrix effect; 20% < |ME| < 50% is medium matrix effect; |ME| > 50% is strong matrix effect. The results are shown in Table 4. Pronamide shows medium matrix effect in tomato and apple matrices, and strong matrix effect in Chinese cabbage, citrus and sugarcane matrices; pymetrozine shows weak matrix effect in tomato matrix and strong matrix effect in the remaining matrices; metconazole and flutriafol show weak matrix effect in tomato matrix and medium matrix effect in the remaining four matrices; pyridazinone shows strong matrix effect in citrus and apple matrices and medium matrix effect in the remaining matrices. Generally speaking, only in tomato matrix, pymetrozine, metconazole and flutriafol show weak matrix effect. Therefore, in the R & D stage of the present invention, matrix-matched standard curves are used for quantitative analysis to reduce the influence of matrix effect on the analysis results.

[0118] Table 4 Matrix effects of five compounds

[0119]

[0120] 2. Method linear range and detection limit:

[0121] According to the experimental method with the chromatographic conditions: "SH-I-5Sil MS capillary column (30m×0.25mm, 0.25μm); injection volume: 1μL, splitless injection; carrier gas: helium; temperature programming: initial temperature is 50°C and held for 1min, then increased to 125°C at a rate of 25°C / min, and then increased to 300°C at a rate of 10°C / min and held for 2min; injection port temperature: 250°C", a series of blank matrix standard solutions with concentrations of 2, 10, 20, 50, 100, 200, 500 μg / L were used. Taking the mass concentration (X) of each target compound (piflufenzide, metazachlor, flutriafol, pyridate, pronamide) as the abscissa and the peak area (Y) as the ordinate, a standard curve was plotted, and external standard method was used for quantitative analysis. The linear equations and correlation coefficients of each target compound were obtained, and the results are shown in Table 5. In the range of 2 - 500 μg / L, the linear coefficients of the five pesticides such as pronamide are all greater than 0.9999, indicating a good linear relationship. Taking the concentration at S / N = 3 as the detection limit and the concentration at S / N = 10 as the quantification limit, it can be seen from the table that the detection limits (LOD) of the five pesticides are in the range of 0.17 - 2.23 μg / kg, and the quantification limits (LOQ) are in the range of 0.55 - 7.44 μg / kg. The quantification limits of each compound detected by this method are all lower than the limit standards of the European Union, Canada and Japan, indicating that this method has high sensitivity and is suitable for the detection of pesticide residues in fruits and vegetables.

[0122] Table 5 Linear relationship, detection limit (LOD) and quantification limit (LOQ) of five compounds

[0123]

[0124] 3. Spike recovery rate and precision of the detection method described in the present invention:

[0125] Five samples of tomato, Chinese cabbage, sugarcane, citrus and apple were selected. Standard substances of clethodim and pymetrozine at three concentration levels of 10.0, 20.0, and 50.0 μg / kg were added to the samples for detection. For the same samples, spiked recovery experiments of three kinds of pesticides, namely fluxapyroxad, flutianil and pyridafol, were carried out at three levels of 5.0, 20.0, and 50.0 μg / kg respectively, and 6 parallel samples were made for each level. The average recovery rate and relative standard deviation (RSD) were calculated. The results are shown in Table 6. At the spiked concentration of 5 μg / kg, the average recovery rate range of fluxapyroxad, flutianil and pyridafol was 74.19% - 110.22%, and the RSD was 0.12% - 5.31%. When the spiked concentration was 10 μg / kg, the average recovery rate of clethodim and pymetrozine was 81.25% - 111.52%, and the RSD was 0.26% - 3.31%. At the spiked levels of 20 μg / kg and 50 μg / kg for the five compounds, the recovery rates were 65.86% - 104.27% and 66.55% - 113.04% respectively, and the RSDs were 0.31% - 6.81% and 0.25% - 6.60% respectively. The experimental results meet the requirements of the European Union and Japan for the average recovery rate and RSD of pesticides. It shows that this method has high accuracy, meets the requirements of laboratory determination, and can be used to detect target compounds in plant-derived foods.

[0126] Table 6 Spiked recovery rates and precisions (RSD) of five compounds

[0127]

[0128] 4. Detection of actual samples:

[0129] The actual detection of 96 batches of fruit and vegetable samples such as tomato, apple and Chinese cabbage was carried out using the present invention. The results showed that no residue of the target compound was detected in all samples.

[0130] 5. Compared with other publicly available technologies:

[0131] The latest pesticide limit standards in China, namely GB 2763 - 2021 and GB 2763.1 - 2022, do not cover the HPLC - MS / MS detection methods and limit requirements for these two herbicides, and there are also few similar studies internationally. Han Sol Lee et al. used QuEChERS combined with LC - MS / MS method to determine the residue of Tolpyralate in five agricultural products, and set the LOQ to 0.01 mg / kg. In contrast, the present invention has a lower quantitative limit and can be applied to the detection of more plant - derived matrices. Therefore, the present invention has more advantages.

[0132] The present invention combines the QuEChERS pretreatment method and the GC-MS / MS detection method to establish a detection method for five new types of pesticide residues in fruit and vegetable products. By optimizing a series of pretreatment conditions, the best detection results are obtained: during the pretreatment process, sodium chloride is used as the extraction salt for the sample, 10 ml of acetonitrile is used for extraction, and 100 mg of PSA, 10 mg of GCB, and 100 mg of C18 are used as the purification materials. The five compounds have good linear relationships. In the precision experiment, the average recovery rates are 65.86% - 113.04%, and the precisions are 0.25% - 6.81%, all of which meet the relevant limit standards for pesticide residues in fruits and vegetables in countries such as the European Union and Japan. This method is simple, fast, with high accuracy and precision, and provides technical support for the daily detection of fruit and vegetable products.

[0133] As described above, it is only a preferred embodiment of the present invention and does not impose any form of limitation on the present invention. Any simple modification or equivalent change made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for detecting 5 new pesticide residues in fruit and vegetable matrices by combining QuEChERS technology with gas chromatography-triple quadrupole mass spectrometry, characterized in that: It includes the following steps: 1) Sample pretreatment: Weigh an appropriate amount of fruit and vegetable samples, and use an extraction solvent, a water remover, an extraction salt, and a purifying agent to obtain the filter residue of the sample to be tested. 2) Solution preparation: Prepare the required standard stock solution, mixed standard working solution, and blank matrix standard solution respectively. 3) Detect the filter residue of the sample to be tested or / and the blank matrix standard solution.

2. The method for detecting 5 new pesticide residues in fruit and vegetable matrices by combining QuEChERS technology with gas chromatography-triple quadrupole mass spectrometry according to claim 1, characterized in that: The step 1) includes the following specific steps: 1.1) Weigh 10 g of fruit and vegetable samples and place them in a 50 ml centrifuge tube. Add 5 - 20 ml of extraction solvent, shake for 5 min for extraction, add 4 g of water remover and 1 g of extraction salt, shake for 10 min, mix well, and centrifuge at 8000 r / min for 5 min. 1.2) After step 1.1), take 6 ml of the supernatant and place it in a 15 ml centrifuge tube. Add 0.9 g of water remover, 50 - 250 mg of the first purifying agent, 0 - 200 mg of the second purifying agent, and 0 - 20 mg of the third purifying agent. Vortex and mix for 5 min, centrifuge at 8000 r / min for 5 min, take 1 ml of the supernatant and filter it through a 0.22 μm organic filter membrane to obtain the filter residue of the sample to be tested.

3. The method for detecting 5 novel pesticide residues in fruit and vegetable matrices by combining QuEChERS technology with gas chromatography-triple quadrupole mass spectrometry according to claim 2, characterized in that: In the step 1.1), the extraction solvent is acetone, ethyl acetate, acetonitrile, or acidic acetonitrile, and the dosage is 10 ml; the water remover is anhydrous magnesium sulfate; the extraction salt is sodium chloride, sodium sulfate, sodium acetate, or sodium carbonate. In the step 1.2), the water remover is anhydrous magnesium sulfate; the first purifying agent is PSA, and the dosage is 0.1 g; the second purifying agent is C18, and the dosage is 0.1 g; the third purifying agent is GCB, and the dosage is 0.01 g.

4. The method for detecting 5 new types of pesticide residues in fruit and vegetable matrices by combining QuEChERS technology with gas chromatography-triple quadrupole mass spectrometry according to claim 3, characterized in that: In the step 1.1), the extraction solvent is acetonitrile, and the extraction salt is sodium chloride.

5. A method for detecting 5 new types of pesticide residues in fruit and vegetable matrices by combining QuEChERS technology with gas chromatography-triple quadrupole mass spectrometry according to any one of claims 1 to 4, characterized in that: The step 2) includes the following specific steps: 2.1) Preparation of standard stock solution: Accurately weigh 0.001 g of the standard of flufenpyr-ethyl in a 10 mL volumetric flask, add acetonitrile to dissolve it and dilute to the mark to prepare a standard stock solution of flufenpyr-ethyl at 100 μg / mL, and store it in the dark at -20 °C for later use; clethodim, pyflubumid, metconazole, and fluopyram are all liquid standard products with a mass concentration of 100 μg / mL, which are directly used as standard stock solutions and stored in the dark at -20 °C for later use. 2.2) Preparation of mixed standard working solution: Accurately measure 1 ml of each of the above five standard stock solutions respectively, dilute them with acetonitrile to prepare 10 ml of a mixed standard intermediate solution at 10 μg / mL, and store it in the dark in a refrigerator at -20 °C; measure an appropriate amount of the mixed standard intermediate solution, dilute it with acetonitrile to prepare a series of mixed standard working solutions with mass concentrations of 2, 10, 20, 50, 100, 200, and 500 μg / L for GC-MS / MS detection. 2.3) Preparation of blank matrix standard solution: After pretreatment, obtain blank samples, and dilute the mixed standard working solution with the blank samples to prepare a series of blank matrix standard solutions with concentrations of 2, 10, 20, 50, 100, 200, and 500 μg / L.

6. The method for detecting 5 new types of pesticide residues in fruit and vegetable matrices by combining QuEChERS technology with gas chromatography-triple quadrupole mass spectrometry according to claim 5, characterized in that: The blank samples are obtained through the following pretreatment method: 2.3.1) Weigh 10 g of fruit and vegetable samples and place them in a 50 ml centrifuge tube. Add 5 - 20 ml of extraction solvent, shake for 5 min for extraction, add 4 g of water remover and 1 g of extraction salt, shake for 10 min, mix well, and centrifuge at 8000 r / min for 5 min; 2.3.2) After step 2.3.1), take 6 ml of the supernatant and place it in a 15 ml centrifuge tube. Add 0.9 g of water remover, 50 - 250 mg of the first purification agent, 0 - 200 mg of the second purification agent, and 0 - 20 mg of the third purification agent, vortex and mix well for 5 min, centrifuge at 8000 r / min for 5 min, take 1 ml of the supernatant and filter it through a 0.22 μm organic filter membrane to obtain a blank sample.

7. The method for detecting 5 new pesticide residues in fruit and vegetable matrices by combining QuEChERS technology with gas chromatography-triple quadrupole mass spectrometry according to claim 8, characterized in that: In step 2.3.1), the extraction solvent is acetone, ethyl acetate, acetonitrile or acidic acetonitrile, and the dosage is 10 ml; the water remover is anhydrous magnesium sulfate; the extraction salt is sodium chloride, sodium sulfate, sodium acetate or sodium carbonate; In step 2.3.2): the water remover is anhydrous magnesium sulfate; the first purification agent is PSA, and the dosage is 0.1 g; the second purification agent is C18, and the dosage is 0.1 g; the third purification agent is GCB, and the dosage is 0.01 g.

8. The method for detecting 5 new types of pesticide residues in fruit and vegetable matrices by combining QuEChERS technology with gas chromatography-triple quadrupole mass spectrometry according to claim 7, characterized in that: In step 2.3.1), the extraction solvent is acetonitrile and the extraction salt is sodium chloride.

9. A method for detecting 5 new pesticide residues in fruit and vegetable matrices by combining QuEChERS technology with gas chromatography-triple quadrupole mass spectrometry according to any one of claims 1 to 4, 6 to 8, characterized in that: When detecting the filter residue of the sample to be tested, use a GC-MS / MS-TQ8040 gas chromatography - mass spectrometry instrument for detection; and during the detection: The chromatographic conditions are: SH-1701 chromatographic column, SH-PolarWAX-MS chromatographic column or SH-I-5Sil MS capillary chromatographic column; injection volume: 1 μL, splitless injection; Carrier gas: helium; temperature programming: the initial temperature is 50°C and is held for 1 min, then heated at a rate of 25°C / min to 125°C, and then heated at a rate of 10°C / min to 300°C and held for 2 min; injection port temperature: 250°C; The mass spectrometry conditions are: ion source temperature: 230°C; interface temperature: 250°C; ionization mode: electron impact source; ionization energy: 70 eV; detector voltage: 1.5 kV; scan mode: multiple reaction monitoring mode; scan mass range: 50 - 550 m / z; solvent delay time: 3.5 min.

10. The method for detecting 5 new types of pesticide residues in fruit and vegetable matrices by combining QuEChERS technology with gas chromatography-triple quadrupole mass spectrometry according to claim 9, characterized in that: When detecting the filter residue of the sample to be tested, use a GC-MS / MS-TQ8040 gas chromatography - mass spectrometry instrument for detection; and during the detection: The chromatographic conditions are: SH-I-5Sil MS capillary chromatographic column; injection volume: 1 μL, splitless injection; carrier gas: helium; temperature programming: the initial temperature is 50°C and is held for 1 min, then heated at a rate of 25°C / min to 125°C, and then heated at a rate of 10°C / min to 300°C and held for 2 min; injection port temperature: 250°C; The mass spectrometry conditions are: ion source temperature: 230°C; interface temperature: 250°C; ionization mode: electron impact source; ionization energy: 70 eV; detector voltage: 1.5 kV; scan mode: multiple reaction monitoring mode; scan mass range: 50 - 550 m / z; solvent delay time: 3.5 min.

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