Single pesticide baseline-based fast screening mass spectrometry multi-pesticide limit judgment method

Abstract

This invention belongs to the field of pesticide residue detection technology, specifically involving a rapid screening mass spectrometry method for determining the limits of multiple pesticides based on a single pesticide baseline. This method, through the design of "single standard baseline + response ratio database", uses triazophos as the standard pesticide. Through preliminary experiments, a response ratio database between the target pesticide and triazophos is established. During detection, the concentration of multiple target pesticides can be calculated by simply using the response value of triazophos. This effectively solves the pain points of existing rapid screening mass spectrometry detection of multiple pesticides, and is suitable for rapid screening in agricultural products, food and other fields, with broad application prospects.

Description

Technical Field

[0001] This invention belongs to the field of pesticide residue detection technology, specifically involving a rapid screening mass spectrometry method for determining the limits of multiple pesticides based on a single pesticide baseline. Background Technology

[0002] Current rapid mass spectrometry methods for detecting multiple pesticide residues require the preparation of corresponding standards for each target pesticide, and the establishment of response-concentration relationships for each pesticide through individual calibration. This approach has the following drawbacks: 1. Large number of standards: Detecting N pesticides requires preparing N different standards, resulting in high procurement and storage costs; 2. High workload: Each standard requires separate optimization of detection conditions and plotting of standard curves, making the process cumbersome; 3. Low efficiency: Calibration with multiple standards leads to long detection cycles, failing to meet the needs of rapid screening; 4. Complex data processing: The concentration of each pesticide needs to be calculated individually, which is time-consuming. Based on these pain points and needs, there is an urgent need to develop a method for rapidly determining the concentrations of multiple pesticides. Summary of the Invention

[0003] The purpose of this invention is to provide a method for determining the limits of multiple pesticides using rapid screening mass spectrometry based on a single pesticide baseline, in order to solve the problems of large number of standards, large workload, low efficiency and complex data processing in the existing rapid screening mass spectrometry detection of multiple pesticide residues.

[0004] According to a first aspect of the present invention, a method for determining the limits of multiple pesticides by rapid screening mass spectrometry based on a single pesticide baseline is provided, using triazophos as a standard pesticide, comprising the following steps: S1. Prepare standard solutions of triazophos and the target pesticide of the same concentration, respectively. Use a rapid screening mass spectrometer under identical conditions to detect and record the response values ​​of triazophos and the target pesticide. The response value of triazophos is denoted as... R 0, the response value of the target pesticide is recorded as R i Calculate the response ratio of the target pesticide to triazophos. K i =R i / R 0; S2. Pretreatment of the sample to be tested yields the sample test solution; triazophos standard with a known concentration C1 (e.g., 0.1 mg / L) is added to the blank matrix solution to obtain the matrix-spiked test solution. The concentration of triazophos standard in the matrix-spiked test solution is recorded as C1' (e.g., 0.01 mg / L). S3. Inject the matrix-spikeped test solution and the sample test solution into the rapid screening mass spectrometer, respectively, and detect and record the response values ​​of triazophos and the target pesticide. The response value of triazophos is denoted as... R 1. The response value of the target pesticide is denoted as... R i’ ; S4. Calculate the target pesticide concentration using the following formula. Ci : ,Will Ci By comparing the residue limit with that of the target pesticide, it can be determined whether the target pesticide exceeds the limit.

[0005] The logic of the formula for calculating the target pesticide concentration in this invention is as follows: In the experiment, R... i =K i ×R0 (at the same concentration), the response coefficient of triazophos during detection is R1 / C1', and the response coefficient of the target pesticide is K. i ×(R1 / C1'), therefore C i =R i ' / [K i ×(R1 / C1')]; The residue limits for the target pesticides can be referenced in the relevant provisions of the National Food Safety Standard for Maximum Residue Limits of Pesticides in Food (GB 2763-2021).

[0006] In addition, triazophos was chosen as the standard pesticide because it is stable and not easily degraded, and because it has a stable response in mass spectrometry and an average mass axis distribution, which ensures the stability and reliability of the results.

[0007] In some embodiments, the preparation method of the triazophos standard solution or target pesticide standard solution in step S1 is as follows: accurately pipette 1000 μL of triazophos stock solution or target pesticide stock solution (1 mg / L) into a 10 mL volumetric flask, then dilute with acetonitrile to obtain an intermediate solution (0.1 mg / L), then pipette 1000 μL of the intermediate solution into a 10 mL volumetric flask, and then dilute with acetonitrile to obtain a triazophos standard solution or target pesticide standard solution with a concentration of 0.01 mg / L.

[0008] In some implementations, in step S1, the response ratio of the target pesticide to triazophos is calculated. K i In this case, at least 100 sets of experiments need to be conducted and the average value taken to ensure that the ratio is stable. For example, the number of experiments can be 200, 500, 800, 1000, 2000, or even more.

[0009] In some implementations, the response of triazophos to the target pesticide needs to be within a linear range, such as 0.01-10 mg / L, to avoid nonlinear errors.

[0010] In some embodiments, the sample pretreatment method in step S2 is as follows: Weigh 10.00g (accurate to 0.01g) of the sample to be tested into a centrifuge tube, add 10mL of acetonitrile, and shake for 1min; add 4g of anhydrous magnesium sulfate, 1g of sodium chloride, 1g of sodium citrate dihydrate, and 0.5g of disodium citrate sesquihydrate, shake, and centrifuge; quantitatively aspirate the first supernatant into a centrifuge tube containing a dehydrating agent and purification material; for samples with darker colors, add GCB (graphite carbon black, 2.5mg per milliliter of extract) to the centrifuge tube, vortex, then centrifuge, and aspirate the second supernatant through a microporous filter membrane; the filtrate is the test solution. For dried vegetables, fruits, and edible fungi, weigh 1.00g of the sample to be tested (accurate to 0.01g) into a centrifuge tube, add 9mL of water, vortex, let stand, and then process as described above. The dehydrating agent can be anhydrous magnesium sulfate, and the purification material can be N-propylethylenediamine (PSA). 150 mg of anhydrous magnesium sulfate and 25 mg of PSA are used per milliliter of the first supernatant.

[0011] More specifically, the sample pretreatment method is as follows: Weigh 10.00g (accurate to 0.01g) of the sample to be tested into a 50mL plastic centrifuge tube, add 10mL of acetonitrile and ceramic homogenizer, and shake vigorously for 1min; add 4g of anhydrous magnesium sulfate, 1g of sodium chloride, 1g of sodium citrate dihydrate, and 0.5g of disodium citrate sesquihydrate, shake vigorously for 55-65s, and centrifuge at 4000-4200r / min for 4-6min; quantitatively aspirate the supernatant into a plastic centrifuge tube containing dehydrating agent and purification material (use 150mg of anhydrous magnesium sulfate and 25mg of PSA per milliliter of extract); for samples with darker colors, add GCB (use 2.5mg per milliliter of extract) to the centrifuge tube, vortex to mix for 55-65s, centrifuge at 4000-4200r / min for 4-6min, and filter the supernatant through a microporous membrane; the filtrate is the test solution. For dried vegetables, fruits and edible fungi, weigh 1g of sample (accurate to 0.01g) into a 50mL plastic centrifuge tube, add 9mL of water, vortex mix, let stand for 25~35 minutes and then process as described above.

[0012] In some embodiments, the sample pretreatment method in step S2 is as follows: take 10.00g of sample, add 20mL of acetonitrile for ultrasonic extraction for 10 minutes, purify by C18 solid phase extraction column, and make up to 10mL to obtain the sample test solution.

[0013] In addition, different samples to be tested can be pretreated according to the steps described in GB 23200.121-2021 National Food Safety Standard for Determination of Residues of 331 Pesticides and Their Metabolites in Plant-Derived Foods by Liquid Chromatography-Mass Spectrometry to obtain the test solution.

[0014] In some embodiments, in step S2, the blank matrix solution is prepared by the following method: a sample of the same type as the sample to be tested but confirmed to have no target pesticide residue is selected as the source of the blank matrix, and processed according to the sample to be tested processing method to obtain the blank matrix solution.

[0015] In some implementations, steps S3 and S1 require the same parameter conditions when using a rapid screening mass spectrometer, such as the same ionization method and ion source parameters, to ensure... constant.

[0016] In some embodiments, the target pesticides include, but are not limited to, methamidophos, dichlorvos, dimethoate, difenoconazole, fenthion, "propiconazole (Bifimon)," propiconazole, pyridaben, chlorpyrifos, triazophos, tebuconazole, acephate (Gao Mifen), imidacloprid, pyraclostrobin, diflubenzuron, dinotefuran, dinotefuran, cymoxanil, iprodione, methamidophos, chlorpyrifos, phorate, methamidophos sulfone, and fenthion. Phosphine sulfoxide, fenthion, chlorpyrifos, thiamethoxam, omethoate, methamidophos, methyl isofenphos, phorate, phorate sulfoxide, bifenthrin, trichlorfon, methomyl, indoxacarb, isoprocarb, aldicarb sulfoxide, aldicarb sulfone, 3-hydroxycarbofuran, aldicarb, carbofuran, acetamiprid, thiamethoxam, thiamethoxam, carbendazim, prochloraz, dimethomorph, cypermethrin, cyazofamid, thiamethoxam, flumorph Tebuconazole, Hexaconazole, Flusilazole, Cyproconazole, Ciprofloxacin, Prochloraz-Deimazolecarbamide, Etoxazole, Pendimethalin, Chlorpyrifos, Fluopyram, Butyrazosulfuron, Terbufos, Apiracetam, Cyclomethrin, Benthiocarb, Thioctanol, Acetochlor, Oxythiophanate-methyl, Terbufos, Isoprothiolane, Triadimefon, Triadimefon, Benzoyl-methyl, Pyridaben, Imidacloprid, Azoxystrobin Ester, phosmet, terbufos sulfone, fluamide, benzalkonium chloride, chlorpyrifos, fenthion, tetraflufenozide, cycloflufenoxam, pyrimethanil, simazine, atrazine, propargite, pyrimethanil, atrazine, chlorpyrifos, isoxaflutole, prochloraz, acetamiprid, phosmet, diazinon, tebufenozide, butachlor, chlorpyrifos, pyridazine, phosmet, pyrimethanil, pyrimethanil, ethion, cypermethrin.

[0017] The present invention provides a rapid screening mass spectrometry method for determining the limits of multiple pesticides based on a single pesticide baseline. This method, through the design of "single standard baseline + response ratio database", uses triazophos as the standard pesticide. Through the preliminary experiment in step S1, a response ratio database between the target pesticide and triazophos is established. During detection, the concentration of multiple target pesticides can be calculated by simply using the response value of triazophos. This effectively solves the pain point of existing rapid screening mass spectrometry detection of multiple pesticides. It is suitable for rapid screening in agricultural products, food and other fields and has broad application prospects.

[0018] According to a second aspect of the present invention, the above-described method for determining multiple pesticide limits using rapid screening mass spectrometry based on a single pesticide baseline is provided for the rapid screening of pesticide residues in agricultural products and food.

[0019] The present invention has the following advantages: 1. Reduce the number of standard samples: Only one triazophos standard sample needs to be prepared, which can replace multiple standard samples of target pesticides, reducing procurement and preparation costs (e.g., if testing 10 pesticides, the number of standard samples is reduced by 90%). 2. Reduced workload: No need to optimize the testing conditions for each pesticide individually, saving operation time (e.g., the time for preparing standard samples is reduced from 2 hours to 0.2 hours). 3. Improve judgment efficiency: By back-calculating the concentration of multiple pesticides using a single standard baseline, the detection cycle is shortened by more than 50% (e.g., from 4 hours to 1.5 hours). 4. Simplified data processing: Only Ki in the database needs to be called, and the concentration can be quickly calculated by combining the response value, reducing data processing time by more than 60%. Attached Figure Description

[0020] Figure 1 This is the mass spectrum of methylamine phosphorus; Figure 2 Mass spectrum of dichlorvos; Figure 3 This is the mass spectrum of triazole phosphorus; Figure 4 This is the mass spectrum of dimethoate. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to specific embodiments. It is worth noting that the following embodiments are only for better explaining the content of the present invention and do not limit the scope of protection of the present invention. The process steps not disclosed in the embodiments are prior art. Unless otherwise specified, the following raw materials are all commercially available. Among them, the pesticides methamidophos, dichlorvos, and dimethoate used in the embodiments are all organophosphorus pesticides. The chemical name of dichlorvos is 2,2-dichlorovinyl dimethyl phosphate, and the chemical name of dimethoate is O,O-dimethyl-S-(N-methylcarbamoylmethyl)dithiophosphate.

[0022] Example 1 Taking the detection of three pesticides, methamidophos, dichlorvos, and dimethoate, in vegetables as an example, the rapid screening mass spectrometry method for determining the limits of multiple pesticides based on a single pesticide baseline includes the following steps: 1. Establish a database Preparation mg / L standard solutions of triazophos, methamidophos, dichlorvos, and dimethoate; Rapid screening mass spectrometry detection (ESI) + (m / z 50-500), the results are as followsFigures 1-4 As shown, we obtain 三唑磷 =10000, R 甲 =8000, R 敌 =12000, R 乐 =9000; Calculate the ratio: K 甲 =8000 / 10000=0.8, K 敌 =12000 / 10000=1.2, K 乐 =9000 / 10000=0.9; Create a database, see Table 1.

[0023] Table 1 Target Pesticide Response Ratio Database

[0024] 2. Sample pretreatment Take 10g of vegetable sample, add 20mL of acetonitrile and extract by ultrasonication for 10 minutes. Purify by C18 solid phase extraction column and make up to 10mL to obtain the sample test solution.

[0025] 3. Add internal standard Add 1 mL to the blank matrix solution A triazophos standard of mg / L was used to prepare a matrix-spiked test solution with a triazophos concentration of 0.1 mg / L. (mg / L).

[0026] The blank matrix solution was prepared as follows: a sample of the same type as the test sample but confirmed to be free of target pesticide residues was selected as the source of the blank matrix, and processed according to the test sample processing method to obtain the blank matrix solution. The sample free of target pesticide residues was selected from the Standard Material Network or standard matrices labeled "free of pesticide residues" in Anpu Laboratory consumables.

[0027] 4. Rapid screening mass spectrometry detection The following was detected: 三唑磷 =1000 (corresponding to) mg / L), R 甲 =700, R 敌 =1300, R 乐 =850.

[0028] 5. Concentration back calculation Methamidophos: C 甲 0.0875 mg / L; Dichlorvos: C 敌 0.108 mg / L; Lego: C 乐 0.094 mg / L.

[0029] 6. Limit value judgment According to GB 2763-2021, the limits for methamidophos are 0.1 mg / L, dichlorvos is 0.2 mg / L, and dimethoate is 0.1 mg / L. The calculated results do not exceed these limits.

[0030] The above descriptions are merely some specific embodiments of the present invention. For those skilled in the art, various modifications and improvements can be made without departing from the inventive concept of the present invention, and all such modifications and improvements fall within the scope of protection of the present invention.

Claims

1. A method for determining the limits of multiple pesticides using rapid mass spectrometry based on a single pesticide baseline, characterized in that, Includes the following steps: S1. Prepare standard solutions of triazophos and the target pesticide of the same concentration, respectively. Use a rapid screening mass spectrometer under identical conditions to detect and record the response values ​​of triazophos and the target pesticide. The response value of triazophos is denoted as... R 0, the response value of the target pesticide is recorded as R i Calculate the response ratio of the target pesticide to triazophos. K i =R i / R 0; S2. Pretreatment of the sample to be tested to obtain the sample solution; Add a triazophos standard of known concentration C1 to a blank matrix solution to obtain a matrix-spiked test solution. The concentration of triazophos standard in the matrix-spiked test solution is denoted as C1'. S3. Inject the matrix-spikeped test solution and the sample test solution into the rapid screening mass spectrometer, respectively, and detect and record the response values ​​of triazophos and the target pesticide. The response value of triazophos is denoted as... R 1. The response value of the target pesticide is denoted as... R i ’ ; S4. Calculate the target pesticide concentration using the following formula. Ci : ,Will Ci By comparing the residue limit with that of the target pesticide, it can be determined whether the target pesticide exceeds the limit.

2. The method for determining the limit values ​​of multiple pesticides based on a single pesticide baseline using rapid screening mass spectrometry according to claim 1, characterized in that, The preparation method of the triazophos standard solution or target pesticide standard solution in step S1 is as follows: accurately pipette 1000 μL of triazophos stock solution or target pesticide stock solution into a 10 mL volumetric flask, then dilute with acetonitrile to obtain an intermediate solution, then pipette 1000 μL of the intermediate solution into a 10 mL volumetric flask, and then dilute with acetonitrile to obtain a triazophos standard solution or target pesticide standard solution with a concentration of 0.01 mg / L.

3. The method for determining the limit values ​​of multiple pesticides based on a single pesticide baseline using rapid screening mass spectrometry according to claim 1, characterized in that, In step S1, the response ratio of the target pesticide to triazophos is calculated. K i At this time, it is necessary to take the average value of at least 100 sets of experiments.

4. The method for determining the limit values ​​of multiple pesticides based on a single pesticide baseline using rapid screening mass spectrometry according to claim 1, characterized in that, The response of triazophos to the target pesticide must be within a linear range, which is 0.01-10 mg / L.

5. The method for determining the limit values ​​of multiple pesticides based on a single pesticide baseline using rapid screening mass spectrometry according to claim 1, characterized in that, In step S2, the sample pretreatment method is as follows: Weigh 10.00g of the sample to be tested into a centrifuge tube, add 10mL of acetonitrile, and shake for 1min; add 4g of anhydrous magnesium sulfate, 1g of sodium chloride, 1g of sodium citrate dihydrate, and 0.5g of disodium citrate sesquihydrate, shake, and centrifuge; quantitatively aspirate the first supernatant into a centrifuge tube containing dehydrating agent and purification material, centrifuge, and aspirate the second supernatant through a microporous filter membrane; the filtrate is the test solution.

6. The method for determining the limit values ​​of multiple pesticides based on a single pesticide baseline using rapid screening mass spectrometry according to claim 1, characterized in that, In step S2, the sample pretreatment method is as follows: Take 10.00g of sample, add 20mL of acetonitrile for ultrasonic extraction for 10 minutes, purify by C18 solid phase extraction column, and make up to 10mL to obtain the sample test solution.

7. The method for determining the limit values ​​of multiple pesticides based on a single pesticide baseline using rapid screening mass spectrometry according to claim 5 or 6, characterized in that, After the first supernatant was added to the centrifuge tube, graphite carbon black was also added, and the mixture was vortexed.

8. The method for determining the limit values ​​of multiple pesticides based on a single pesticide baseline using rapid screening mass spectrometry according to claim 1, characterized in that, In step S2, the blank matrix solution is prepared by the following method: a sample of the same type as the sample to be tested but confirmed to have no target pesticide residue is selected as the source of blank matrix, and processed according to the sample to be tested processing method to obtain the blank matrix solution.

9. The method for determining the limit values ​​of multiple pesticides based on a single pesticide baseline using rapid screening mass spectrometry according to claim 1, characterized in that, When using a rapid screening mass spectrometer for detection in steps S3 and S1, the same parameter conditions must be maintained.

10. The application of the rapid screening mass spectrometry method for determining multiple pesticide limits based on a single pesticide baseline as described in any one of claims 1-9 in the rapid screening of pesticide residues in agricultural products and food.

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