Method for detecting residual pesticide in food

Abstract

The invention relates to a food pesticide residue detection method, and belongs to the technical field of pesticide residue detection.According to the technical scheme, prepared green light-emitting cadmium telluride quantum dot (at) MOF-808 fluorescent composite materials and MOF-5 / red light-emitting cadmium telluride quantum dot molecularly imprinted polymer fluorescent composite materials are used as fluorescent probes; the fluorescent probe can simultaneously detect paraoxon, acetamiprid and clothianidin, and has the advantages of accurate detection result, low detection limit and rapid and stable detection.

Description

Technical Field

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

[0002] Pesticides are chemical agents used in modern agriculture to prevent and control pests and diseases and regulate plant growth. In modern agricultural production, pesticides are important means of production for preventing and controlling pests and diseases, ensuring agricultural harvests, and ensuring food supply. However, excessive pesticide residues 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 more and more arduous.

[0003] At present, the traditional detection methods mainly include instrumental analysis (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 immunoassays, etc.). Although these methods can achieve accurate detection of pesticides, they have the disadvantages of cumbersome operation or dependence on large and expensive instruments, which is not convenient for realizing rapid and portable detection of pesticide residues. Fluorescence analysis 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 capabilities prepared by in-situ copolymerization of functional monomers around template molecules, but the fluorescent molecularly imprinted polymers currently prepared have low adsorption efficiency and long response time for template molecules. In addition, the currently commonly used single-emission fluorescent probes with independent fluorescent signals are greatly affected by probe concentration, instrument noise and sample environment, and are not easy to show obvious color changes. The construction of a dual-color fluorescent probe based on ratio fluorescence sensing can significantly enhance color contrast and improve detection sensitivity. Therefore, it is necessary to provide a method for detecting pesticide residues in food that can solve the above problems. Summary of the invention

[0004] The object of the present invention is to provide a method for detecting pesticide residues in food, using the prepared green luminescent cadmium telluride quantum dots@MOF-808 fluorescent composite material and MOF-5 / red luminescent cadmium telluride quantum dots molecular imprinted polymer fluorescent composite material as fluorescent probes, the fluorescent probes can simultaneously detect paraoxon, acetamiprid and clothianidin, and have the advantages of accurate detection results, low detection limit, and fast and stable detection.

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

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

[0007] A method for detecting pesticide residues in food comprises the following steps:

[0008] 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 520 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 paraoxon in food pesticide residues through the relationship between the change in the ratio of the absorption peak intensity at 400 nm to the fluorescence intensity at 520 nm and the paraoxon concentration;

[0009] 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 acetamiprid or clothianidin in residual pesticides in food is achieved.

[0010] Furthermore, the preparation method of the green luminescent 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 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;

[0012] Furthermore, 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.

[0013] Furthermore, in the step A1, the usage ratio of sodium tellurite and sodium borohydride to 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, 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.

[0015] Furthermore, in 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.

[0016] In the above preparation process, green luminescent cadmium telluride quantum dots are deposited in MOF-808, thereby improving the dispersion of green luminescent cadmium telluride quantum dots. MOF-808 can catalyze the degradation of paraoxon to produce yellow p-nitrophenol, which has an ultraviolet absorption peak at a wavelength of 400nm. Green luminescent cadmium telluride quantum dots have good stability and can be used as a reference signal, thereby effectively avoiding interference with detection by other impurities or the environment.

[0017] Furthermore, the preparation method of the MOF-5 / cadmium telluride quantum dot molecular imprinted polymer fluorescent composite material comprises 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 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 green luminescent cadmium telluride quantum dots; then prepare a 0.03-0.05 mg / mL red emitting cadmium telluride quantum dot solution with deionized water;

[0019] Furthermore, 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.

[0020] Furthermore, in the step B1, the usage ratio of sodium tellurite and sodium borohydride to 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 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;

[0022] Furthermore, in 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.

[0023] 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;

[0024] Furthermore, in 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.

[0025] 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.

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

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

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

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

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

[0031] Furthermore, in step B4, the mass ratio of MOF-5 / red luminescent cadmium telluride quantum dot fluorescent composite material, functional monomer, template molecule, cross-linking agent and 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, MOF-5 is treated with acid to obtain hollow MOF-5, and then red luminescent cadmium telluride quantum dots are uniformly attached to the surface of the hollow MOF-5, and finally the molecular imprinting polymer is coated to obtain MOF-5 / red luminescent cadmium telluride quantum dot molecular imprinting polymer fluorescent composite material. Since MOF-5 is first treated with acid and then coated with molecular imprinting polymer, the obtained MOF-5 / red luminescent cadmium telluride quantum dot molecular imprinting polymer fluorescent composite material has a high specific surface area, which improves the adsorption efficiency and mass transfer efficiency of the molecular imprinting polymer to the template molecule, thereby shortening the response time, and can quickly and accurately detect acetamiprid and clothianidin. In addition, the green luminescent cadmium telluride quantum dots in the green luminescent cadmium telluride quantum dots@MOF-808 fluorescent composite material can be used as a reference signal to effectively avoid interference with detection by other impurities or the environment.

[0033] Beneficial effects of the present invention:

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

[0035] (2) In the technical solution of the present invention, MOF-5 is treated with acid and then coated with a molecular imprinting polymer, so that the obtained MOF-5 / red luminescent cadmium telluride quantum dot molecular imprinting polymer fluorescent composite material has a high specific surface area, which improves the adsorption efficiency and mass transfer efficiency of the molecular imprinting polymer to the template molecule, thereby shortening the response time, and can quickly and accurately detect acetamiprid and clothianidin. In addition, the green luminescent cadmium telluride quantum dots in the green luminescent cadmium telluride quantum dot@MOF-808 fluorescent composite material can be used as a reference signal to effectively avoid interference with detection by other impurities or the environment.

[0036] (3) In the technical solution of the present invention, green luminescent cadmium telluride quantum dots are deposited in MOF-808, thereby improving the dispersibility of green luminescent cadmium telluride quantum dots. MOF-808 can catalyze the degradation of paraoxon to produce yellow p-nitrophenol, which has an ultraviolet absorption peak at a wavelength of 400nm. Green luminescent cadmium telluride quantum dots have good stability and can be used as a reference signal, thereby effectively avoiding interference with detection by other impurities or the environment. DETAILED DESCRIPTION

[0037] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] Example 1

[0039] This embodiment provides a method for preparing a green luminescent cadmium telluride quantum dot@MOF-808 fluorescent composite material, comprising the following steps:

[0040] A1. Mix 0.12g of sodium tellurite and 0.70g of sodium borohydride with 27mL of deionized water to obtain a mixed solution; dissolve 0.6g of cadmium chloride in 220mL of deionized water, add 1g of reducing L-glutathione and 2.1g of trisodium citrate, add 0.1mol / L of sodium hydroxide solution to adjust the pH of the solution to 10.5, add the mixed solution and 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 prepare a 0.02mg / 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, ultrasonically treat for 35 min, add 50 mL of green-emitting cadmium telluride quantum dot solution, react at 120 °C for 42 h, centrifuge, wash and dry to obtain a green-emitting cadmium telluride quantum dot@MOF-808 fluorescent composite material.

[0042] Example 2

[0043] This embodiment provides a method for preparing a MOF-5 / red luminescent cadmium telluride quantum dot molecularly imprinted polymer fluorescent composite material, comprising the following steps:

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

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

[0046] B3, adding 9 mL of red luminescent cadmium telluride quantum dot solution to 0.78 g of acid-treated MOF-5, stirring for 18 h, centrifuging, washing, and drying to obtain a MOF-5 / red luminescent cadmium telluride quantum dot fluorescent composite material;

[0047] B4. Disperse 0.28g of MOF-5 / red luminescent cadmium telluride quantum dot fluorescent composite material in 20mL of ethanol, add 0.33g of methacrylic acid and methanol solution of acetamiprid and clothianidin (the molar ratio of acetamiprid and clothianidin is 1:1, and the total mass of acetamiprid and clothianidin is 0.03g), stir and react for 2h, then add 1mL of ethylene glycol dimethacrylate and 0.046g of azobisisobutyronitrile, pass nitrogen, and react at 53°C for 19h. 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 (the volume ratio of methanol and acetic acid is 9:1) as an eluent to elute the template molecule to obtain MOF-5 / red luminescent cadmium telluride quantum dot molecular imprinting polymer fluorescent composite material.

[0048] Example 3

[0049] A method for detecting pesticide residues in food comprises the following steps:

[0050] 3 mg of the green luminescent cadmium telluride quantum dot @MOF-808 fluorescent composite material prepared in Example 1 and 1.2 mg of the MOF-5 / red luminescent cadmium telluride quantum dot molecular imprinted polymer fluorescent composite material prepared in Example 2 were dispersed in 10 mL of deionized water to obtain a suspension, 80 μL of the suspension was taken, 50 μL of paraoxon of different concentrations and 350 μL of 1.5 mM N-ethylmorpholine buffer solution (pH=7.8) were added to the suspension, and the mixture was reacted at 37° C. for 15 min, and then the fluorescence spectrum was measured at a laser wavelength of 350 nm using a fluorescence spectrophotometer, and the fluorescence intensity at 520 nm was recorded; then the supernatant was taken out by centrifugation to measure the ultraviolet-visible absorption spectrum, and the absorption peak intensity of the oxidation product p-nitrophenol corresponding to different concentrations of paraoxon at 400 nm was obtained, and a standard curve was drawn through the relationship between the change in the ratio of the absorption peak intensity at 400 nm to the fluorescence intensity at 520 nm and the paraoxon concentration, which had a good linear relationship; the linear equation was y 1 =0.0932x 1 +0.0158, R 2 =0.9976, linear range 0.01-200μM, detection limit as low as 11.4nM, where: y 1 is the ratio of the absorption peak intensity at 400nm to the fluorescence intensity at 520nm, x 1 is the concentration of paraoxon. 1 =0.0932x 1 +0.0158, which can realize the quantitative detection of the pesticide paraoxon residue in food.

[0051] Example 4

[0052] A method for detecting pesticide residues in food comprises the following steps:

[0053] 1.5 mg of the green-luminescent cadmium telluride quantum dot@MOF-808 fluorescent composite material prepared in Example 1 and 1.9 mg of the MOF-5 / red-luminescent cadmium telluride quantum dot molecular imprinting polymer fluorescent composite material prepared in Example 2 were dispersed in 10 mL of deionized water to obtain a suspension, 100 μL of the suspension was taken, 100 μL of acetamiprid of different concentrations and 500 μL of 50 mM phosphate buffer solution (pH=7.5) were added to the suspension, and the suspension was shaken in the dark for 7 minutes, and then the fluorescence spectrum was measured at a laser wavelength of 350 nm using a fluorescence spectrophotometer, and the fluorescence intensity at 520 nm and 628 nm was recorded; a standard curve was drawn 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 concentration, which had a good linear relationship; the linear equation was y 2 =-0.1432x 2 +0.7746, R 2 =0.9969, linear range 0.01-10mg / L, detection limit as low as 1μg / L, where: y 2 is the ratio of the fluorescence intensity at 628 nm and 520 nm, x 2 is the log value of acetamiprid concentration. 2 =-0.1432x 2 +0.7746, which can realize the quantitative detection of the pesticide acetamiprid residue in food.

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

[0055] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall 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 520 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 520 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 green luminescent cadmium telluride quantum dots; 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. A 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.