Pesticide residue detection method for food safety detection

Abstract

The invention discloses a pesticide residue detection method for food safety detection, which comprises the following steps: step 1, sample treatment: treating a sample for later use; step 2, determining chromatographic conditions, preparing an organophosphorus pesticide standard stock solution and an organophosphorus pesticide standard working solution, and separating and determining chromatographic columns of dichlorvos, dimethoate, malathion and parathion; separating and determining the chromatographic columns of phorate, fenoxanil, fenthion, effective centipede sulfur phosphorus and chlorfenapyr; determining airflow velocity and temperature; step 3, respectively injecting the standard working solutions of the organophosphorus pesticide into a gas chromatograph, measuring the peak heights of the organophosphorus standard solutions with different concentrations, respectively drawing quality-peak height standard curves of the organophosphorus pesticide, simultaneously injecting the sample solutions into the gas chromatograph, measuring the peak heights, and finding out the corresponding content from the standard curve graph; compared with the prior art, the method has the advantage that the content of the organophosphorus pesticide in the sample can be calculated.

Description

Technical Field

[0001] The invention relates to the technical field of food pesticide residue detection, in particular to a pesticide residue detection method for food safety detection. Background Art

[0002] As agricultural intensification and industrialization deepen, the variety and amount of insecticides and herbicides used around the world continue to increase, and the resulting safety issues such as pesticide residues have attracted widespread attention. After use, pesticide preparations are transferred and accumulated through various pathways, including direct plant absorption and environmental medium transfer. In particular, systemic pesticides will be retained inside crops due to penetration and diffusion, and are difficult to remove by ordinary washing. In addition, in agricultural processes such as different growth stages and crop rotation, the sequential and combined application of multiple pesticides will cause compound pollution of agricultural chemicals, further causing risks to human health and undermining the stability of the ecosystem.

[0003] The organophosphorus pesticides remaining in food are extracted with organic solvents, purified, and concentrated, then injected into a gas chromatograph, separated in a chromatographic column by a carrier gas after vaporization, and detected by a flame photometer. When the sample containing organophosphorus burns on the hydrogen-rich flame in the detector, it emits characteristic light with a wavelength of 526nm in the form of HPO fragments. This light is filtered out by the monochromator (filter) of the detector to remove the non-characteristic spectrum, and then received by a photomultiplier tube to generate an electrical signal for detection. The peak area or peak height of the sample is quantitatively compared with the peak area or peak height of the standard, so a method for detecting pesticide residues in food safety testing is proposed. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the above technical defects and provide a method for detecting pesticide residues for food safety detection.

[0005] In order to solve the above problems, the technical solution of the present invention is a method for detecting pesticide residues in food safety detection, which comprises the following steps:

[0006] Step 1, sample treatment, the sample is treated for later use, the sample includes one of vegetables and grains, and the vegetable treatment method is as follows: take the vegetables, wipe them clean, remove the inedible parts, weigh the vegetable sample, chop the vegetables and mix them evenly; weigh the mixed sample, put it in a stoppered conical bottle, add anhydrous sodium sulfate for dehydration, add activated carbon for decolorization, add dichloromethane, shake on an oscillator, filter through filter paper, measure the filtrate, evaporate it naturally at room temperature in a fume hood until it is nearly dry, wash the residue with dichloromethane in small amounts for multiple times, transfer it into a stoppered graduated test tube, and make up to volume for later use;

[0007] Step 2, determining the chromatographic conditions, preparing standard stock solutions and standard working solutions of organophosphorus pesticides, separating and determining chlorpyrifos, dimethoate, malathion and parathion on the chromatographic column; separating and determining phorate, chlorpyrifos, fenthion, fenthion and chlorpyrifos on the chromatographic column; determining the air flow velocity and temperature;

[0008] Step 3, inject the organophosphorus pesticide standard solution into the gas chromatograph respectively, measure the peak height of the organophosphorus standard solution of different concentrations, draw the organophosphorus pesticide mass-peak height standard curve respectively, and take the sample solution and inject it into the gas chromatograph at the same time, measure the peak height, and find out the corresponding content from the standard curve.

[0009] Further, 9-11 g of the mixed sample in step 1 is weighed, and the conical flask is plugged to 250 mL, 30 g-100 g of anhydrous sodium sulfate is added for dehydration, 0.2 g-0.8 g of activated carbon is added for decolorization, 60-80 mL of dichloromethane is added, and the mixture is shaken on an oscillator for 0.4-0.6 h, filtered through filter paper, 35 mL of the filtrate is measured, and naturally evaporated to near dryness at room temperature in a fume hood, and the residue is washed with dichloromethane in small amounts for multiple times, transferred into a 10 mL stoppered graduated test tube, and the volume is fixed to 2 mL.

[0010] Furthermore, the grain processing method in step 1 is to shell and grind the sample, pass it through a 20-mesh sieve, mix it evenly, weigh the sample and place it in a stoppered conical flask, add neutral alumina and dichloromethane, shake it, filter it, and directly inject the filtrate. If the pesticide residue is too low, add dichloromethane, shake and filter it, measure the filtrate, concentrate it, and make it to the volume for injection.

[0011] Furthermore, when the grains are processed, 9-11 g are weighed and placed in a stoppered conical flask, 0.4-0.6 g of neutral alumina and 18-22 mL of dichloromethane are added, the mixture is shaken for 0.4-0.6 h, filtered, the filtrate is directly injected, 15 mL of the filtrate is concentrated, and the volume is adjusted to 2 mL for injection.

[0012] Furthermore, the chromatographic column has an inner diameter of 3 mm and a length of 1.5 m-2.0 m. The gas flow rate: carrier gas is nitrogen 80 mL / min; air 50 mL / min; hydrogen 180 mL / min. The temperature is as follows: injection port: 220°C; detector: 240°C; column temperature: 180°C, and the dichlorvos concentration is measured to be 130°C.

[0013] Further, it is characterized in that: the standard stock solution of the organophosphorus pesticide is prepared by weighing 10.0 mg each of the organophosphorus pesticide standard products dichlorvos, dimethoate, malathion, parathion, phorate, chlorpyrifos, fenthion, cypermethrin and chlorpyrifos, dissolving them with benzene (or chloroform) and diluting them to 100 mL, and storing them in a cold storage; the standard working solution of the organophosphorus pesticide is prepared by diluting it with dichloromethane to obtain a working solution so that its concentration is 1.0 ug per milliliter of dichlorvos, dimethoate, malathion, parathion and phorate, and 2.0 ug per milliliter of chlorpyrifos, fenthion, cypermethrin and chlorpyrifos.

[0014] Further, the calculation formula is:

[0015] X = A / (m*100), calculate the content of organophosphorus pesticide in the sample;

[0016] Where X is the content of organophosphorus pesticide in the sample, in mg / Kg; A is the mass of organophosphorus pesticide in the injection volume, obtained from the standard curve, in ng; m is the mass of the sample equivalent to the injection volume (uL), in g.

[0017] The advantages of the present invention compared with the prior art are:

[0018] 1. The present invention can measure the peak heights of organophosphorus standard solutions of different concentrations by injecting organophosphorus pesticide standard use solutions into a gas chromatograph, respectively, and draw organophosphorus pesticide mass-peak height standard curves respectively. At the same time, a sample solution is injected into a gas chromatograph to measure the peak height, and the corresponding content is found out from the standard curve. DETAILED DESCRIPTION

[0019] In order to make the contents of the present invention more clearly understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention.

[0020] Embodiment 1

[0021] A method for detecting pesticide residues for food safety detection comprises the following steps:

[0022] Step 1, sample treatment, vegetable treatment samples are set aside, and the vegetable treatment method is as follows: weigh 9g of the mixed sample, plug a conical flask to 250mL, add 30g of anhydrous sodium sulfate for dehydration, add 0.2g of activated carbon for decolorization, add 60mL of dichloromethane, shake on an oscillator for 0.4h, filter through filter paper, measure 35mL of the filtrate, evaporate naturally at room temperature in a fume hood until nearly dry, wash the residue with dichloromethane in small amounts for multiple times, transfer to a 10mL stoppered graduated test tube, and make up to 2mL;

[0023] Step 2, determining the chromatographic conditions, preparing standard stock solutions and standard working solutions of organophosphorus pesticides, separating and determining chlorpyrifos, dimethoate, malathion and parathion on the chromatographic column; separating and determining phorate, chlorpyrifos, fenthion, fenthion and chlorpyrifos on the chromatographic column; determining the air flow velocity and temperature;

[0024] Preparation of standard stock solution of organophosphorus pesticides: weigh 10.0 mg each of organophosphorus pesticide standard products such as dichlorvos, dimethoate, malathion, parathion, phorate, pyraclostrobin, fenthion, cypermethrin and chlorpyrifos, dissolve them in benzene (or chloroform) and dilute to 100 mL, and store in cold storage; the standard working solution of organophosphorus pesticides is prepared by diluting it with dichloromethane to a working solution with a concentration of 1.0 ug per milliliter of dichlorvos, dimethoate, malathion, parathion and phorate, and 2.0 ug per milliliter of pyraclostrobin, fenthion, cypermethrin and chlorpyrifos.

[0025] Step 3, injecting the organophosphorus pesticide standard solution into the gas chromatograph respectively, the inner diameter of the chromatographic column is 3mm, the length is 1.5mm, the gas flow rate: the carrier gas is nitrogen 80mL / min; air 50mL / min; hydrogen 180mL / min, the temperature, injection port: 220°C; detector: 240°C; column temperature: 180°C, the dichlorvos is measured at 130°C, the peak heights of organophosphorus standard solutions of different concentrations can be measured, and the organophosphorus pesticide mass-peak height standard curves are drawn respectively. At the same time, the sample solution is injected into the gas chromatograph, the peak height is measured, and the corresponding content is found out from the standard curve.

[0026] The calculation formula is: X = A / (m*100), and the content of organophosphorus pesticide in the sample is calculated;

[0027] Where X is the content of organophosphorus pesticide in the sample, in mg / Kg; A is the mass of organophosphorus pesticide in the injection volume, obtained from the standard curve, in ng; m is the mass of the sample equivalent to the injection volume (uL), in g.

[0028] Embodiment 2

[0029] A method for detecting pesticide residues for food safety detection comprises the following steps:

[0030] Step 1, sample treatment, vegetable treatment samples are set aside, and the vegetable treatment method is as follows: weigh 10g of the mixed sample, plug a conical flask to 250mL, add 65g of anhydrous sodium sulfate for dehydration, add 0.5g of activated carbon for decolorization, add 70mL of dichloromethane, shake on an oscillator for 0.5h, filter through filter paper, measure 35mL of the filtrate, evaporate naturally at room temperature in a fume hood until nearly dry, wash the residue with dichloromethane in small amounts for multiple times, transfer it into a 10mL stoppered graduated test tube, and make up to 2mL;

[0031] Step 2, determining the chromatographic conditions, preparing standard stock solutions and standard working solutions of organophosphorus pesticides, separating and determining chlorpyrifos, dimethoate, malathion and parathion on the chromatographic column; separating and determining phorate, chlorpyrifos, fenthion, fenthion and chlorpyrifos on the chromatographic column; determining the air flow velocity and temperature;

[0032] Preparation of standard stock solution of organophosphorus pesticides: weigh 10.0 mg each of organophosphorus pesticide standard products such as dichlorvos, dimethoate, malathion, parathion, phorate, pyraclostrobin, fenthion, cypermethrin and chlorpyrifos, dissolve them in benzene (or chloroform) and dilute to 100 mL, and store in cold storage; the standard working solution of organophosphorus pesticides is prepared by diluting it with dichloromethane to a working solution with a concentration of 1.0 ug per milliliter of dichlorvos, dimethoate, malathion, parathion and phorate, and 2.0 ug per milliliter of pyraclostrobin, fenthion, cypermethrin and chlorpyrifos.

[0033] Step 3, injecting the organophosphorus pesticide standard solution into the gas chromatograph respectively, the inner diameter of the chromatographic column is 3mm, the length is 1.5mm, the gas flow rate: the carrier gas is nitrogen 80mL / min; air 50mL / min; hydrogen 180mL / min, the temperature, injection port: 220°C; detector: 240°C; column temperature: 180°C, the dichlorvos is measured at 130°C, the peak heights of organophosphorus standard solutions of different concentrations can be measured, and the organophosphorus pesticide mass-peak height standard curves are drawn respectively. At the same time, the sample solution is injected into the gas chromatograph, the peak height is measured, and the corresponding content is found out from the standard curve.

[0034] The calculation formula is: X = A / (m*100), and the content of organophosphorus pesticide in the sample is calculated;

[0035] Where X is the content of organophosphorus pesticide in the sample, in mg / Kg; A is the mass of organophosphorus pesticide in the injection volume, obtained from the standard curve, in ng; m is the mass of the sample equivalent to the injection volume (uL), in g.

[0036] Embodiment 3

[0037] A method for detecting pesticide residues for food safety detection comprises the following steps:

[0038] Step 1, sample treatment, vegetable treatment samples are set aside, and the vegetable treatment method is as follows: weigh 11g of the mixed sample, plug a conical flask to 250mL, add 100g of anhydrous sodium sulfate for dehydration, add 0.8g of activated carbon for decolorization, add 80mL of dichloromethane, shake on an oscillator for 0.6h, filter through filter paper, measure 35mL of the filtrate, evaporate naturally at room temperature in a fume hood until nearly dry, wash the residue with dichloromethane in small amounts for multiple times, transfer it into a 10mL stoppered graduated test tube, and make up to 2mL;

[0039] Step 2, determining the chromatographic conditions, preparing standard stock solutions and standard working solutions of organophosphorus pesticides, separating and determining chlorpyrifos, dimethoate, malathion and parathion on the chromatographic column; separating and determining phorate, chlorpyrifos, fenthion, fenthion and chlorpyrifos on the chromatographic column; determining the air flow velocity and temperature;

[0040] Preparation of standard stock solution of organophosphorus pesticides: weigh 10.0 mg each of organophosphorus pesticide standard products such as dichlorvos, dimethoate, malathion, parathion, phorate, pyraclostrobin, fenthion, cypermethrin and chlorpyrifos, dissolve them in benzene (or chloroform) and dilute to 100 mL, and store in cold storage; the standard working solution of organophosphorus pesticides is prepared by diluting it with dichloromethane to a working solution with a concentration of 1.0 ug per milliliter of dichlorvos, dimethoate, malathion, parathion and phorate, and 2.0 ug per milliliter of pyraclostrobin, fenthion, cypermethrin and chlorpyrifos.

[0041] Step 3, injecting the organophosphorus pesticide standard solution into the gas chromatograph respectively, the inner diameter of the chromatographic column is 3mm, the length is 1.5mm, the gas flow rate: the carrier gas is nitrogen 80mL / min; air 50mL / min; hydrogen 180mL / min, the temperature, injection port: 220°C; detector: 240°C; column temperature: 180°C, the dichlorvos is measured at 130°C, the peak heights of organophosphorus standard solutions of different concentrations can be measured, and the organophosphorus pesticide mass-peak height standard curves are drawn respectively. At the same time, the sample solution is injected into the gas chromatograph, the peak height is measured, and the corresponding content is found out from the standard curve.

[0042] The calculation formula is: X = A / (m*100), and the content of organophosphorus pesticide in the sample is calculated;

[0043] Where X is the content of organophosphorus pesticide in the sample, in mg / Kg; A is the mass of organophosphorus pesticide in the injection volume, obtained from the standard curve, in ng; m is the mass of the sample equivalent to the injection volume (uL), in g.

[0044] Embodiment 4

[0045] A method for detecting pesticide residues for food safety detection comprises the following steps:

[0046] Step 1, sample treatment, grain treatment sample standby, the grain treatment method is as follows, weigh 10g and put it in a stoppered conical flask, add 0.5g neutral alumina and 20mL dichloromethane, shake for 0.5h, filter, directly inject the filtrate, measure 15mL of the filtrate, concentrate it, and dilute it to 2mL for injection;

[0047] Step 2, determining the chromatographic conditions, preparing standard stock solutions and standard working solutions of organophosphorus pesticides, separating and determining chlorpyrifos, dimethoate, malathion and parathion on the chromatographic column; separating and determining phorate, chlorpyrifos, fenthion, fenthion and chlorpyrifos on the chromatographic column; determining the air flow velocity and temperature;

[0048] Preparation of standard stock solution of organophosphorus pesticides: weigh 10.0 mg each of organophosphorus pesticide standard products such as dichlorvos, dimethoate, malathion, parathion, phorate, pyraclostrobin, fenthion, cypermethrin and chlorpyrifos, dissolve them in benzene (or chloroform) and dilute to 100 mL, and store in cold storage; the standard working solution of organophosphorus pesticides is prepared by diluting it with dichloromethane to a working solution with a concentration of 1.0 ug per milliliter of dichlorvos, dimethoate, malathion, parathion and phorate, and 2.0 ug per milliliter of pyraclostrobin, fenthion, cypermethrin and chlorpyrifos.

[0049] Step 3, injecting the organophosphorus pesticide standard solution into the gas chromatograph respectively, the inner diameter of the chromatographic column is 3mm, the length is 1.5mm, the gas flow rate: the carrier gas is nitrogen 80mL / min; air 50mL / min; hydrogen 180mL / min, the temperature, injection port: 220°C; detector: 240°C; column temperature: 180°C, the dichlorvos is measured at 130°C, the peak heights of organophosphorus standard solutions of different concentrations can be measured, and the organophosphorus pesticide mass-peak height standard curves are drawn respectively. At the same time, the sample solution is injected into the gas chromatograph, the peak height is measured, and the corresponding content is found out from the standard curve.

[0050] The calculation formula is: X = A / (m*100), and the content of organophosphorus pesticide in the sample is calculated;

[0051] Where X is the content of organophosphorus pesticide in the sample, in mg / Kg; A is the mass of organophosphorus pesticide in the injection volume, obtained from the standard curve, in ng; m is the mass of the sample equivalent to the injection volume (uL), in g.

[0052] The present invention and its implementation methods are described above, and such description is not restrictive. In short, if ordinary technicians in the field are inspired by it, without departing from the purpose of the invention, they can design structures and embodiments similar to the technical solution without creativity, which should all fall within the protection scope of the present invention.

Claims

1. A method for detecting pesticide residues in food safety testing, characterized in that: The following steps are involved: Step 1, sample treatment, the sample is treated for later use, the sample includes one of vegetables and grains, and the vegetable treatment method is as follows: take the vegetables, wipe them clean, remove the inedible parts, weigh the vegetable sample, chop the vegetables and mix them evenly; weigh the mixed sample, put it in a stoppered conical bottle, add anhydrous sodium sulfate for dehydration, add activated carbon for decolorization, add dichloromethane, shake on an oscillator, filter through filter paper, measure the filtrate, evaporate it naturally at room temperature in a fume hood until it is nearly dry, wash the residue with dichloromethane in small amounts for multiple times, transfer it into a stoppered graduated test tube, and make up to volume for later use; Step 2, determining the chromatographic conditions, preparing standard stock solutions and standard working solutions of organophosphorus pesticides, separating and determining chlorpyrifos, dimethoate, malathion and parathion on the chromatographic column; separating and determining phorate, chlorpyrifos, fenthion, fenthion and chlorpyrifos on the chromatographic column; determining the air flow velocity and temperature; Step 3, inject the organophosphorus pesticide standard solution into the gas chromatograph respectively, measure the peak height of the organophosphorus standard solution of different concentrations, draw the organophosphorus pesticide mass-peak height standard curve respectively, and take the sample solution and inject it into the gas chromatograph at the same time, measure the peak height, and find out the corresponding content from the standard curve chart.

2. The method for detecting pesticide residues in food safety according to claim 1, characterized in that: In the step 1, 9-11 g of the mixed sample of vegetables is weighed, and the conical flask is plugged to 250 mL, 30 g-100 g of anhydrous sodium sulfate is added for dehydration, 0.2 g-0.8 g of activated carbon is added for decolorization, and 60-80 mL of dichloromethane is added. The mixture is shaken on an oscillator for 0.4-0.6 h, filtered through filter paper, 35 mL of the filtrate is measured, and naturally evaporated to near dryness at room temperature in a fume hood, and the residue is washed with dichloromethane in small amounts for multiple times, transferred into a 10 mL stoppered graduated test tube, and the volume is fixed to 2 mL.

3. The method for detecting pesticide residues in food safety according to claim 1, characterized in that: The method for processing the grains in step 1 is to shell and grind the sample, pass it through a 20-mesh sieve, mix it evenly, weigh the sample and place it in a stoppered conical flask, add neutral alumina and dichloromethane, shake it, filter it, and directly inject the filtrate. If the pesticide residue is too low, add dichloromethane, shake it, filter it, measure the filtrate, concentrate it, and make it to the volume for injection.