A method for detecting residual pesticides in food

Abstract

The present invention relates to a method for detecting residual pesticides in food, belonging to the technical field of pesticide residue detection. In the technical solution of the present invention, the prepared green-emitting cadmium telluride quantum dot@MOF-808 fluorescent composite material and MOF-5 / red-emitting cadmium telluride quantum dot molecularly imprinted polymer fluorescent composite material are used as fluorescent probes. This fluorescent probe can simultaneously detect parathion, acetamiprid, and clothianidin, and has the advantages of accurate detection results, low detection limit, and fast and stable detection.

Description

Technical Field

[0001] The present invention belongs to the technical field of pesticide residue detection, and specifically relates to a method for detecting residual pesticides in food. Background Art

[0002] Pesticides are chemical agents used in modern agriculture to control pests and diseases and regulate plant growth. In modern agricultural production, pesticides are important production materials for controlling pests and diseases, ensuring a bumper harvest of agriculture, and ensuring food supply. However, excessive pesticides remaining on crops and pesticide residue metabolites in agricultural and livestock products can enter the human body through the digestive tract, causing varying degrees of damage to the human body and affecting people's health. With the improvement of people's living standards, the requirements for the quality and safety of agricultural products are getting higher and higher, and the task of detecting pesticide residues in agricultural products is becoming heavier and heavier.

[0003] Currently, traditional detection methods mainly include instrumental analysis methods (such as gas chromatography-mass spectrometry, gas chromatography, liquid chromatography, infrared spectroscopy, ultraviolet spectroscopy, etc.) and detection methods based on biotechnology (such as biosensors, enzyme inhibition methods, and immunoassay methods, etc.). Although these methods can achieve accurate detection of pesticides, they have disadvantages such as cumbersome operation or reliance on large and expensive instruments, and are not convenient for rapid and portable detection of pesticide residues. Fluorescence analysis method has gradually become an important method for detecting pesticides due to its advantages such as simple operation, low detection cost, and short time consumption. Molecularly imprinted polymers are polymers with specific recognition ability prepared by in-situ copolymerization of functional monomers around template molecules. However, currently prepared fluorescent molecularly imprinted polymers have problems such as low adsorption efficiency for template molecules and long response time. In addition, currently commonly used single-emission fluorescent probes with independent fluorescence signals are greatly affected by probe concentration, instrument noise, and sample environment, and it is not easy to present obvious color changes. Constructing a dual-color fluorescent probe based on ratio fluorescence sensing can significantly enhance the color contrast and improve the detection sensitivity. Therefore, it is necessary to provide a method for detecting residual pesticides in food that can solve the above problems. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for detecting residual pesticides in food. The prepared green-emitting cadmium telluride quantum dot@MOF-808 fluorescent composite material and MOF-5 / red-emitting cadmium telluride quantum dot molecularly imprinted polymer fluorescent composite material are used as fluorescent probes. This fluorescent probe can simultaneously detect parathion, acetamiprid, and clothianidin, and has the advantages of accurate detection results, low detection limit, and rapid and stable detection.

[0005] Technical problems to be solved by the present invention: The currently prepared fluorescent molecularly imprinted polymers have problems of low adsorption efficiency for template molecules and long response time. In addition, the commonly used single-emission fluorescent probes with independent fluorescent signals are greatly affected by probe concentration, instrument noise, and sample environment, and it is not easy to present obvious color changes.

[0006] The object of the present invention can be achieved by the following technical solutions:

[0007] A method for detecting residual pesticides in food, comprising the following steps:

[0008] S1. Disperse 2 - 4 mg of green-emitting cadmium telluride quantum dot@MOF-808 fluorescent composite material and 0.5 - 2 mg of MOF-5 / cadmium telluride quantum dot molecularly imprinted polymer fluorescent composite material in 10 mL of deionized water to obtain a suspension. Add different concentrations of paraoxon and N-ethylmorpholine buffer solution to the suspension, react at 35 - 40 °C for 10 - 20 min, then measure the fluorescence spectrum using a fluorescence spectrophotometer at a laser wavelength of 350 nm, and record the fluorescence intensity at 628 nm; then centrifuge to take out the supernatant and measure the ultraviolet-visible absorption spectrum to obtain the absorption peak intensity of the oxidation product p-nitrophenol corresponding to different concentrations of paraoxon at 400 nm. Through the relationship between the change in the ratio of the absorption peak intensity at 400 nm and the fluorescence intensity at 628 nm and the concentration of paraoxon, quantitative detection of paraoxon in residual pesticides in food is achieved;

[0009] S2. Disperse 1 - 2 mg of green-emitting cadmium telluride quantum dot@MOF-808 fluorescent composite material and 1.5 - 2.7 mg of MOF-5 / cadmium telluride quantum dot molecularly imprinted polymer fluorescent composite material in 10 mL of deionized water to obtain a suspension. Add different concentrations of acetamiprid or clothianidin and phosphate buffer solution to the suspension, react under light avoidance and oscillation for 5 - 10 min, then measure the fluorescence spectrum using a fluorescence spectrophotometer at a laser wavelength of 350 nm, and record the fluorescence intensities at 520 nm and 628 nm; through the relationship between the change in the ratio of the fluorescence intensities at 628 nm and 520 nm and the log value of the concentration of acetamiprid or clothianidin, quantitative detection of acetamiprid or clothianidin in residual pesticides in food is achieved.

[0010] Furthermore, the preparation method of the green-emitting cadmium telluride quantum dot@MOF-808 fluorescent composite material comprises the following steps:

[0011] A1. Dissolve cadmium chloride in deionized water, add reducing L - glutathione and trisodium citrate, add 0.1 mol / L sodium hydroxide solution to adjust the pH of the solution to 10.5, then add a mixed solution of sodium tellurite and sodium borohydride in deionized water, stir until the solution turns light green, reflux at 100 °C for 2 h, perform alcohol precipitation, centrifugation, and drying to obtain green - emitting cadmium telluride quantum dots; then prepare a green - emitting cadmium telluride quantum dot solution with a concentration of 0.01 - 0.03 mg / mL using deionized water;

[0012] Further, in step A1, the dosage ratio of cadmium chloride, deionized water, reducing L - glutathione, and trisodium citrate is 0.6 g:220 mL:1 g:2.1 g.

[0013] Further, in step A1, the dosage ratio of sodium tellurite, sodium borohydride, and deionized water is 0.12 g:0.7 g:27 mL.

[0014] A2. Add 1,3,5 - benzenetricarboxylic acid and zirconium oxychloride octahydrate to N,N - dimethylformamide and formic acid, perform ultrasonic treatment for 30 - 40 min, add the green - emitting cadmium telluride quantum dot solution, react at 110 - 130 °C for 36 - 48 h, perform centrifugation, washing, and drying to obtain a green - emitting cadmium telluride quantum dot@MOF - 808 fluorescent composite material.

[0015] Further, in step A2, the dosage ratio of 1,3,5 - benzenetricarboxylic acid, zirconium oxychloride octahydrate, N,N - dimethylformamide, formic acid, and the green - emitting cadmium telluride quantum dot solution is 1.1 - 1.3 g:5.3 - 5.5 g:220 - 240 mL:160 - 180 mL:40 - 60 mL.

[0016] During the above - mentioned preparation process, the green - emitting cadmium telluride quantum dots are deposited in MOF - 808, thereby improving the dispersibility of the green - emitting cadmium telluride quantum dots. MOF - 808 can catalytically degrade paraoxon to produce yellow p - nitrophenol, and p - nitrophenol has an ultraviolet absorption peak at a wavelength of 400 nm. The green - emitting cadmium telluride quantum dots have good stability and can be used as a reference signal, thus effectively avoiding interference from other impurities or the environment to the detection.

[0017] Further, a preparation method of a MOF - 5 / cadmium telluride quantum dot molecularly imprinted polymer fluorescent composite material includes the following steps:

[0018] B1. Dissolve cadmium chloride in deionized water, add reducing L - glutathione and trisodium citrate, add 0.1 mol / L sodium hydroxide solution to adjust the pH of the solution to 10.5, then add a mixed solution of sodium tellurite and sodium borohydride and deionized water, stir until the solution turns light green, reflux at 100 °C for 10 h, perform alcohol precipitation, centrifugation, and drying to obtain red - emitting cadmium telluride quantum dots; then prepare a red - emitting cadmium telluride quantum dot solution with a concentration of 0.03 - 0.05 mg / mL using deionized water;

[0019] Further, in the step B1, the dosage ratio of cadmium chloride, deionized water, reducing L - glutathione, and trisodium citrate is 0.62 g: 230 mL: 1 g: 2 g.

[0020] Further, in the step B1, the dosage ratio of sodium tellurite, sodium borohydride, and deionized water is 0.12 g: 0.71 g: 30 mL.

[0021] B2. Dissolve zinc nitrate hexahydrate and terephthalic acid in N,N - dimethylformamide, ultrasonically disperse for 20 - 40 min, then magnetically stir for 18 - 24 h, perform centrifugation, washing, and drying to obtain MOF - 5; disperse MOF - 5 in deionized water, add acetic acid and stir evenly, react at 150 - 170 °C for 2 - 5 h, perform centrifugation, washing, and drying to obtain acid - treated MOF - 5;

[0022] Further, in the step B2, the dosage ratio of zinc nitrate hexahydrate, terephthalic acid, N,N - dimethylformamide, deionized water, and acetic acid is (0.56 - 0.62) g: (0.12 - 0.14) g: (30 - 45) mL: (40 - 50) mL: (2 - 3.5) mL.

[0023] B3. Add the red - emitting cadmium telluride quantum dot solution to the acid - treated MOF - 5, stir for 12 - 24 h, perform centrifugation, washing, and drying to obtain the MOF - 5 / red - emitting cadmium telluride quantum dot fluorescent composite material;

[0024] Further, in the step B3, the dosage ratio of the acid - treated MOF - 5 and the red - emitting cadmium telluride quantum dot solution is (0.6 - 0.9) g: (5 - 12) mL.

[0025] B4. Disperse the MOF-5 / red-emitting cadmium telluride quantum dot fluorescent composite material in ethanol, add the methanol solution of the functional monomer and the template molecule, stir and react for 1 - 3 h, then add the cross-linking agent and the initiator, introduce nitrogen, and react at 50 - 60 °C for 12 - 24 h. After the reaction, centrifuge to remove the supernatant, wash it several times with the ethanol solution of acetonitrile, centrifuge to remove the supernatant, and then use the mixed solution of methanol and acetic acid as the eluent to elute the template molecule to obtain the MOF-5 / red-emitting cadmium telluride quantum dot molecularly imprinted polymer fluorescent composite material.

[0026] Further, in the step B4, the functional monomer is methacrylic acid.

[0027] Further, in the step B4, the template molecules are acetamiprid and clothianidin, and the molar ratio of acetamiprid to clothianidin is 1:1.

[0028] Further, in the step B4, the cross-linking agent is ethylene glycol dimethacrylate.

[0029] Further, in the step B4, the initiator is azobisisobutyronitrile.

[0030] Further, in the step B4, the volume ratio of methanol to acetic acid is 8 - 9:1 - 2.

[0031] Further, in the step B4, the mass ratio of the MOF-5 / red-emitting cadmium telluride quantum dot fluorescent composite material, the functional monomer, the template molecule, the cross-linking agent and the initiator is (2.5 - 3) g:(2 - 4.5) g:(0.1 - 0.5) g:(7 - 13) mL:(0.3 - 0.6) g.

[0032] In the above preparation process, acid-treat the MOF-5 to obtain hollow MOF-5, then uniformly attach the red-emitting cadmium telluride quantum dots on the surface of the hollow MOF-5, and finally coat the molecularly imprinted polymer to obtain the MOF-5 / red-emitting cadmium telluride quantum dot molecularly imprinted polymer fluorescent composite material. Since the MOF-5 is acid-treated first and then coated with the molecularly imprinted polymer, the obtained MOF-5 / red-emitting cadmium telluride quantum dot molecularly imprinted polymer fluorescent composite material has a high specific surface area, improving the adsorption efficiency and mass transfer efficiency of the molecularly imprinted polymer for the template molecule, thereby shortening the response time and enabling rapid and accurate detection of acetamiprid and clothianidin. In addition, the green-emitting cadmium telluride quantum dots in the green-emitting cadmium telluride quantum dot@MOF-808 fluorescent composite material can be used as a reference signal to effectively avoid the interference of other impurities or the environment on the detection.

[0033] The beneficial effects of the present invention:

[0034] (1) In the technical solution of the present invention, the prepared green-emitting cadmium telluride quantum dot@MOF-808 fluorescent composite material and MOF-5 / red-emitting cadmium telluride quantum dot molecularly imprinted polymer fluorescent composite material can simultaneously detect paraoxon, acetamiprid and clothianidin, and have the advantages of accurate detection results, low detection limit, and fast and stable detection.

[0035] (2) In the technical solution of the present invention, MOF-5 is acid-treated and then coated with a molecularly imprinted polymer, so that the obtained MOF-5 / red-emitting cadmium telluride quantum dot molecularly imprinted polymer fluorescent composite material has a high specific surface area, improving the adsorption efficiency and mass transfer efficiency of the molecularly imprinted polymer for the template molecule, thereby shortening the response time and enabling rapid and accurate detection of acetamiprid and clothianidin. In addition, the green-emitting cadmium telluride quantum dots in the green-emitting cadmium telluride quantum dot@MOF-808 fluorescent composite material can serve as a reference signal, effectively avoiding interference from other impurities or the environment to the detection.

[0036] (3) In the technical solution of the present invention, the green-emitting cadmium telluride quantum dots are deposited in MOF-808, thereby improving the dispersibility of the green-emitting cadmium telluride quantum dots. MOF-808 can catalyze the degradation of paraoxon to produce yellow p-nitrophenol, and p-nitrophenol has an ultraviolet absorption peak at a wavelength of 400 nm. The green-emitting cadmium telluride quantum dots have good stability and can serve as a reference signal, thus effectively avoiding interference from other impurities or the environment to the detection. Specific embodiments

[0037] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0038] Example 1

[0039] This example provides a preparation method for a green-emitting cadmium telluride quantum dot@MOF-808 fluorescent composite material, including the following steps:

[0040] A1. Mix 0.12 g of sodium tellurite and 0.70 g of sodium borohydride with 27 mL of deionized water to obtain a mixed solution; dissolve 0.6 g of cadmium chloride in 220 mL of deionized water, add 1 g of reducing L - glutathione and 2.1 g of trisodium citrate, adjust the pH of the solution to 10.5 with 0.1 mol / L sodium hydroxide solution, then add the mixed solution and stir until the solution turns light green. Reflux at 100 °C for 2 h, perform alcohol precipitation, centrifugation, and drying to obtain green - emitting cadmium telluride quantum dots; then prepare a 0.02 mg / mL green - emitting cadmium telluride quantum dot solution with deionized water;

[0041] A2. Add 1.2 g of 1,3,5 - benzenetricarboxylic acid and 5.4 g of zirconium oxychloride octahydrate to 230 mL of N,N - dimethylformamide and 170 mL of formic acid, perform ultrasonic treatment for 35 min, add 50 mL of the green - emitting cadmium telluride quantum dot solution, react at 120 °C for 42 h, perform centrifugation, washing, and drying to obtain a green - emitting cadmium telluride quantum dot@MOF - 808 fluorescent composite material.

[0042] Example 2

[0043] This example provides a preparation method of a MOF - 5 / red - emitting cadmium telluride quantum dot molecularly imprinted polymer fluorescent composite material, which includes the following steps:

[0044] B1. Mix 0.12 g of sodium tellurite and 0.71 g of sodium borohydride with 30 mL of deionized water to obtain a mixed solution; dissolve 0.62 g of cadmium chloride in 230 mL of deionized water, add 1 g of reducing L - glutathione and 2 g of trisodium citrate, adjust the pH of the solution to 10.5 with 0.1 mol / L sodium hydroxide solution, then add the mixed solution and stir until the solution turns light green. Reflux at 100 °C for 10 h, perform alcohol precipitation, centrifugation, and drying to obtain red - emitting cadmium telluride quantum dots; then prepare a 0.04 mg / mL red - emitting cadmium telluride quantum dot solution with deionized water;

[0045] B2. Dissolve 0.58 g of zinc nitrate hexahydrate and 0.13 g of terephthalic acid in 40 mL of N,N - dimethylformamide, perform ultrasonic dispersion for 30 min, then stir magnetically for 21 h, perform centrifugation, washing, and drying to obtain MOF - 5; disperse MOF - 5 in 45 mL of deionized water, add 2.8 mL of acetic acid and stir evenly, react at 160 °C for 3 h, perform centrifugation, washing, and drying to obtain acid - treated MOF - 5;

[0046] B3. Add 9 mL of the red - emitting cadmium telluride quantum dot solution to 0.78 g of acid - treated MOF - 5, stir for 18 h, perform centrifugation, washing, and drying to obtain a MOF - 5 / red - emitting cadmium telluride quantum dot fluorescent composite material;

[0047] B4. Disperse 0.28 g of MOF-5 / red-emitting cadmium telluride quantum dot fluorescent composite material in 20 mL of ethanol, add 0.33 g of methacrylic acid and a methanol solution of acetamiprid and clothianidin (the molar ratio of acetamiprid to clothianidin is 1:1, and the total mass of acetamiprid and clothianidin is 0.03 g), stir and react for 2 h, then add 1 mL of ethylene glycol dimethacrylate and 0.046 g of azobisisobutyronitrile, introduce nitrogen, react at 53 °C for 19 h. After the reaction, centrifuge to remove the supernatant, wash it several times with an ethanol solution of acetonitrile, centrifuge to remove the supernatant, and then use a mixed solution of methanol and acetic acid (the volume ratio of methanol to acetic acid is 9:1) as the eluent to elute the template molecules to obtain the MOF-5 / red-emitting cadmium telluride quantum dot molecularly imprinted polymer fluorescent composite material.

[0048] Example 3

[0049] A method for detecting residual pesticides in food, comprising the following steps:

[0050] Disperse 3 mg of the green-emitting cadmium telluride quantum dot@MOF-808 fluorescent composite material prepared in Example 1 and 1.2 mg of the MOF-5 / red-emitting cadmium telluride quantum dot molecularly imprinted polymer fluorescent composite material prepared in Example 2 in 10 mL of deionized water to obtain a suspension. Take 80 μL of the suspension, add 50 μL of paraoxon at different concentrations and 350 μL of an N-ethylmorpholine buffer solution with a concentration of 1.5 mM (pH = 7.8) to the suspension, react at 37 °C for 15 min, then measure the fluorescence spectrum using a fluorescence spectrophotometer at a laser wavelength of 350 nm, and record the fluorescence intensity at 628 nm; then centrifuge to take out the supernatant and measure the ultraviolet-visible absorption spectrum to obtain the absorption peak intensity of the oxidation product p-nitrophenol corresponding to paraoxon at different concentrations at 400 nm. By the relationship between the change in the ratio of the absorption peak intensity at 400 nm and the fluorescence intensity at 628 nm and the concentration of paraoxon, a standard curve is plotted, which has a good linear relationship; the linear equation is y 1 = 0.0932x 1 + 0.0158, R 2 = 0.9976, the linear range is 0.01 - 200 μM, and the detection limit is as low as 11.4 nM, where: y 1 is the ratio of the absorption peak intensity at 400 nm and the fluorescence intensity at 628 nm, and x 1 is the concentration of paraoxon. Through the linear equation y 1 = 0.0932x 1 + 0.0158, quantitative detection of the residual pesticide paraoxon in food can be achieved.

[0051] Example 4

[0052] A method for detecting residual pesticides in food, comprising the following steps:

[0053] Disperse 1.5 mg of the green-emitting cadmium telluride quantum dot@MOF-808 fluorescent composite prepared in Example 1 and 1.9 mg of the MOF-5 / red-emitting cadmium telluride quantum dot molecularly imprinted polymer fluorescent composite prepared in Example 2 in 10 mL of deionized water to obtain a suspension. Take 100 μL of the suspension, add 100 μL of acetamiprid at different concentrations and 500 μL of a phosphate buffer solution with a concentration of 50 mM (pH = 7.5) to the suspension, react under dark light with shaking for 7 min, then measure the fluorescence spectrum using a fluorescence spectrophotometer at a laser wavelength of 350 nm, and record the fluorescence intensities at 520 nm and 628 nm; by the relationship between the change in the ratio of the fluorescence intensities at 628 nm and 520 nm and the log value of the acetamiprid concentration, plot a standard curve, which has a good linear relationship; the linear equation is y 2 =-0.1432x 2 +0.7746, R 2 =0.9969, the linear range is 0.01 - 10 mg / L, and the detection limit is as low as 1 μg / L, where: y 2 is the ratio of the fluorescence intensities at 628 nm and 520 nm, and x 2 is the log value of the acetamiprid concentration. Through the linear equation y 2 =-0.1432x 2 +0.7746, the quantitative detection of the residual pesticide acetamiprid in food can be achieved.

[0054] In the description of the specification, the description referring to terms such as "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0055] The above content is only an example and explanation of the present invention. Those skilled in the art of this technology can make various modifications or supplements to the described specific embodiments or use similar methods for substitution, as long as they do not deviate from the invention or exceed the scope defined by the claims of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A method for detecting pesticide residues in food, characterized in that: The following steps are involved: S1. Disperse 2-4 mg of green luminescent cadmium telluride quantum dots @MOF-808 fluorescent composite material and 0.5-2 mg of MOF-5 / cadmium telluride quantum dots molecular imprinting polymer fluorescent composite material in 10 mL of deionized water to obtain a suspension, add different concentrations of paraoxon and N-ethylmorpholine buffer solution to the suspension, react at 35-40° C. for 10-20 min, then measure the fluorescence spectrum at a laser wavelength of 350 nm using a fluorescence spectrophotometer, and record the fluorescence intensity at 628 nm; then centrifuge and take out the supernatant to measure the UV-visible absorption spectrum to obtain the absorption peak intensity of the oxidation product p-nitrophenol corresponding to different concentrations of paraoxon at 400 nm, and realize the quantitative detection of the residual pesticide paraoxon in food through the relationship between the change in the ratio of the absorption peak intensity at 400 nm to the fluorescence intensity at 628 nm and the paraoxon concentration; S2. Disperse 1-2 mg of green luminescent cadmium telluride quantum dot @MOF-808 fluorescent composite material and 1.5-2.7 mg of MOF-5 / cadmium telluride quantum dot molecular imprinting polymer fluorescent composite material in 10 mL of deionized water to obtain a suspension, add different concentrations of acetamiprid or clothianidin and phosphate buffer solution to the suspension, shake and react for 5-10 minutes in the dark, and then use a fluorescence spectrophotometer to measure the fluorescence spectrum at a laser wavelength of 350 nm, and record the fluorescence intensity at 520 nm and 628 nm; through the relationship between the change in the ratio of the fluorescence intensity at 628 nm and 520 nm and the log value of the acetamiprid or clothianidin concentration, the quantitative detection of the pesticide residues acetamiprid or clothianidin in food is achieved.

2. The method for detecting pesticide residues in food according to claim 1, characterized in that: The preparation method of the green luminescent cadmium telluride quantum dot@MOF-808 fluorescent composite material comprises the following steps: A1. Dissolve cadmium chloride in deionized water, add reducing L-glutathione and trisodium citrate, add 0.1 mol / L sodium hydroxide solution to adjust the solution pH to 10.5, then add a mixture of sodium tellurite, sodium borohydride and deionized water, stir until the solution turns light green, reflux at 100°C for 2h, precipitate with alcohol, centrifuge and dry to obtain green luminescent cadmium telluride quantum dots; and then prepare a 0.01-0.03 mg / mL green emitting cadmium telluride quantum dot solution with deionized water; A2. Add 1,3,5-benzenetricarboxylic acid and zirconium oxychloride octahydrate to N,N-dimethylformamide and formic acid, ultrasonically treat for 30-40 minutes, add green emitting cadmium telluride quantum dot solution, react at 110-130°C for 36-48 hours, centrifuge, wash and dry to obtain green emitting cadmium telluride quantum dot@MOF-808 fluorescent composite material.

3. A method for detecting pesticide residues in food according to claim 2, characterized in that: In the step A1, the usage ratio of cadmium chloride, deionized water, reduced L-glutathione and trisodium citrate is 0.6 g:220 mL:1 g:2.1 g; the usage ratio of sodium tellurite and sodium borohydride to deionized water is 0.12 g:0.7 g:27 mL.

4. The method for detecting pesticide residues in food according to claim 2, characterized in that: In the step A2, the usage ratio of 1,3,5-benzenetricarboxylic acid, zirconium oxychloride octahydrate, N,N-dimethylformamide, formic acid and green-emitting cadmium telluride quantum dot solution is 1.1-1.3 g: 5.3-5.5 g: 220-240 mL: 160-180 mL: 40-60 mL.

5. The method for detecting pesticide residues in food according to claim 1, characterized in that: The preparation method of the MOF-5 / cadmium telluride quantum dot molecular imprinted polymer fluorescent composite material comprises the following steps: B1. Dissolve cadmium chloride in deionized water, add reducing L-glutathione and trisodium citrate, add 0.1 mol / L sodium hydroxide solution to adjust the solution pH to 10.5, then add a mixture of sodium tellurite, sodium borohydride and deionized water, stir until the solution turns light green, reflux at 100°C for 10h, precipitate with alcohol, centrifuge and dry to obtain red luminescent cadmium telluride quantum dots; and then prepare a 0.03-0.05 mg / mL red emitting cadmium telluride quantum dot solution with deionized water; B2. Dissolve zinc nitrate hexahydrate and terephthalic acid in N,N-dimethylformamide, ultrasonically disperse for 20-40 minutes, magnetically stir for 18-24 hours, centrifuge, wash, and dry to obtain MOF-5; disperse MOF-5 in deionized water, add acetic acid and stir evenly, react at 150-170°C for 2-5 hours, centrifuge, wash, and dry to obtain acid-treated MOF-5; B3, adding a red luminescent cadmium telluride quantum dot solution to the acid-treated MOF-5, stirring for 12-24 hours, centrifuging, washing, and drying to obtain a MOF-5 / red luminescent cadmium telluride quantum dot fluorescent composite material; B4. Disperse the MOF-5 / red luminescent cadmium telluride quantum dot fluorescent composite material in ethanol, add methanol solution of functional monomer and template molecule, stir and react for 1-3h, then add cross-linking agent and initiator, introduce nitrogen, and react at 50-60℃ for 12-24h. After the reaction, centrifuge to remove the supernatant, wash several times with ethanol solution of acetonitrile, centrifuge to remove the supernatant, and then use a mixed solution of methanol and acetic acid as eluent to elute the template molecule to obtain MOF-5 / red luminescent cadmium telluride quantum dot molecular imprinting polymer fluorescent composite material.

6. The method for detecting pesticide residues in food according to claim 5, characterized in that: In the step B1, the usage ratio of cadmium chloride, deionized water, reduced L-glutathione and trisodium citrate is 0.62 g: 230 mL: 1 g: 2 g; the usage ratio of sodium tellurite and sodium borohydride to deionized water is 0.12 g: 0.71 g: 30 mL.

7. The method for detecting pesticide residues in food according to claim 5, characterized in that: In the step B2, the usage ratio of zinc nitrate hexahydrate, terephthalic acid, N,N-dimethylformamide, deionized water and acetic acid is (0.56-0.62) g: (0.12-0.14) g: (30-45) mL: (40-50) mL: (2-3.5) mL.

8. The method for detecting pesticide residues in food according to claim 5, characterized in that: In the step B3, the usage ratio of the acid-treated MOF-5 and the red luminescent cadmium telluride quantum dot solution is (0.6-0.9) g: (5-12) mL.

9. The method for detecting pesticide residues in food according to claim 5, characterized in that: In the step B4, the template molecules are acetamiprid and clothianidin, and the molar ratio of acetamiprid to clothianidin is 1:

1.

10. The method for detecting pesticide residues in food according to claim 5, characterized in that: In the step B4, the mass ratio of the MOF-5 / red luminescent cadmium telluride quantum dot fluorescent composite material, the functional monomer, the template molecule, the cross-linking agent and the initiator is (2.5-3) g: (2-4.5) g: (0.1-0.5) g: (7-13) mL: (0.3-0.6) g.