Magnetic molecularly imprinted material for detecting various pollutants and detection method

Abstract

The invention belongs to the field of biomedical detection, and particularly relates to a magnetic molecularly imprinted material for detecting various pollutants and a detection method. According to the invention, a magnetic Fe3O4 material is wrapped by inorganic SiO2, and then a layer of organic-inorganic hybrid SiO2 nanoparticles is wrapped. The preparation method comprises the following steps: performing high-temperature treatment to form pores on the surfaces of organic-inorganic hybrid SiO2 nanoparticles to improve the adsorption of a target object, then performing activation dispersion treatment to obtain a SiO2 (at) Fe3O4 material with better dispersity, and finally introducing a molecularly imprinted layer on the surface of the modified magnetic SiO2 (at) Fe3O4 material to prepare the magnetic molecularly imprinted material. And the material is combined with a solid-phase extraction technology, so that the extraction of pollutants in urine is realized. And then detecting by high performance liquid chromatography. According to the method, the interference of impurities is effectively reduced, and the quantification accuracy is improved. Therefore, the detection on the micro pollutants is more sensitive.

Description

Technical Field

[0001] The present invention belongs to the field of biomedical detection, and particularly relates to a magnetic molecularly imprinted material for detecting multiple pollutants and a detection method thereof. Background Art

[0002] Pesticides, as a kind of highly efficient insecticides, have been widely used in agricultural production. With the wide application of pollutants, many problems have emerged. Since pollutants have a long biological half-life in the environment, there are trace amounts of pollutants in soil, water sources, etc. Although most pollutants do not directly pollute water sources, they will enter water sources through rainwater scouring, soil infiltration, etc. after being used on crops. The content of pollutants in surface waters such as the Yangtze River is relatively high (Spatiotemporal distribution and fates of neonicotinoid insecticides during the urban water cycle in the lower reaches of the Yangtze River, China. Water Research, 2022, 226: 119232.). And these water sources enter the human body through drinking water or the food chain, thus causing potential harm to human health. Trace amounts of pesticide residues can often be detected in human urine. For example, neonicotinoids, traditional pyrethroid insecticides, phenoxycarboxylic acid herbicides, organophosphorus insecticides, triazine herbicides, etc. Therefore, the detection of pollutants in human urine is of great significance.

[0003] Common detection methods for pollutants include high performance liquid chromatography, enzyme-linked immunosorbent assay, surface enhanced Raman spectroscopy, etc. However, there are many impurities in human urine and the content of pollutants is low, so generally the sample to be detected needs to be pretreated. For example, solid-liquid extraction, liquid-liquid extraction, QuEChERS, solid phase extraction, magnetic solid phase extraction. The main purpose of these sample pretreatment methods is to enrich the substance to be detected and separate it from impurities.

[0004] The key to efficiently enriching the target to be detected lies in the adsorption of the adsorbent. The molecular imprinting technique can combine the target to be detected with the molecular imprinting host and has the advantage of adsorbing the target from a complex matrix. The magnetic molecular imprinting technique can more effectively enrich the target and is easily separated from impurities. Fe3O4 nanoparticles are common magnetic materials, but their poor dispersibility and easy oxidation lead to a decrease in their performance of adsorbing the target. Summary of the Invention

[0005] To overcome the drawbacks of the prior art, the present invention provides a magnetic molecularly imprinted material for detecting multiple pollutants. The magnetic molecularly imprinted material is composed of SiO2@Fe3O4 microspheres. The SiO2 microspheres are divided into two layers. The middle layer is dense, which can prevent Fe3O4 from being oxidized and losing its magnetism. The outer layer of SiO2 has many pores, which can increase the specific surface area and thus enhance the adsorption of the target substance. In addition, the SiO2@Fe3O4 microspheres in the magnetic molecularly imprinted material have good dispersibility. The better the dispersibility of the nanometer microspheres, the larger the specific surface area and the better the adsorption effect, thereby further improving its adsorption of the target substance.

[0006] The technical solution adopted by the present invention to solve its technical problems is as follows:

[0007] A magnetic molecularly imprinted material for detecting multiple pollutants is provided, including: magnetic Fe3O4 microspheres, a SiO2 shell, and a molecular imprinting template. The size particle diameter of the magnetic Fe3O4 microspheres is 79.3 - 154.5 nm. The SiO2 shell is divided into two layers. The outer layer contains a large number of pores, and the inner layer has a dense structure. The overall thickness is 11.2 - 32.5 nm. Among them, the SiO2 shell wraps the magnetic Fe3O4 microspheres, and the molecular imprinting template adheres to the surface of the SiO2 shell.

[0008] The SiO2 on the outer layer of the Fe3O4 microspheres is composed of two layers. The inner layer has a dense structure to prevent the Fe3O4 microspheres from being oxidized and losing their magnetism. The outer layer of SiO2 has a large number of pores, which can improve its adsorption of the target substance.

[0009] The present invention also provides a preparation method of a magnetic molecularly imprinted material for detecting multiple pollutants. The preparation method includes the following steps:

[0010] S1. 0.4 - 1.2 g of FeCl3·6H2O, 0 - 0.1 g of PVP, and 15 - 30 mL of deionized water are subjected to a hydrothermal reaction at 120 - 200 °C for 8 - 12 h. After the reaction ends, monodisperse Fe2O3 microspheres are obtained by centrifugation and washing.

[0011] S2. The Fe2O3 microspheres in step S1 are dispersed in 30 - 60 mL of absolute ethanol. Then, 0.6 - 2 mL of tetraethyl orthosilicate and 2 - 4 mL of ammonia water are added and reacted for 5 - 12 h. Then, 0.5 - 1 mL and 0.2 - 1 mL of N-[3-(trimethoxysilyl)propyl]ethylenediamine are added as silicon sources and reacted for 5 - 12 h. After the reaction ends, SiO2-coated Fe2O3 microspheres are obtained by centrifugation, washing, and drying. Finally, they are calcined in 3 - 5% H2 and 97 - 95% N2 at 300 - 400 °C for 2 - 3 h to obtain SiO2@Fe3O4 powder.

[0012] S3. Add 0.2 - 1 g of the SiO2@Fe3O4 powder obtained in step S2 into 5 - 15 mL of an aqueous methanesulfonic acid solution with a mass ratio of 0.2 - 1 wt%, stir at 80 - 120 °C for 4 h, then obtain the SiO2@Fe3O4 powder by centrifugation, add it into 30 - 100 mL of absolute ethanol, then add 0.3 - 2 mL of ammonia water and 0.1 - 1 mL of silane coupling agent KH-570, and stir at 30 - 55 °C for 5 - 10 h to obtain a modified SiO2@Fe3O4 microsphere sol;

[0013] S4. Place 100 - 300 mg of the pollutant standard in a flask, add 30 - 100 mL of acetonitrile, 4 - 12 mL of deionized water and 0.1 - 0.5 mL of methacrylic acid, stir for 3 - 5 h, then add 10 - 50 mL of the modified SiO2@Fe3O4 microsphere sol obtained in step S3. Then successively add 8 - 30 mmol of trimethylolpropane trimethacrylate and 20 - 60 mg of 2,2'-azobisisobutyronitrile, stir thoroughly for 16 - 20 h, and then wash repeatedly with acetonitrile by centrifugation until the pollutant standard cannot be detected and set aside.

[0014] In step S2, two different SiO2 shells are synthesized by two different hydrolysis methods. The inner layer has a dense structure to prevent the Fe3O4 microspheres from being oxidized and losing magnetism. The outer layer of SiO2 will form a large number of pores after high-temperature treatment, which can improve its adsorption of the target substance. In addition, the SiO2@Fe3O4 powder is obtained by H2 reduction at high temperature, and the high-temperature condition will cause the SiO2@Fe3O4 microspheres to agglomerate, resulting in difficulty in dispersion. In step S3, the surface of the SiO2 shell is treated with methanesulfonic acid, so that the SiO2 surface has more activated hydroxyl groups. Then it is modified with silane coupling agent KH-570 to make it have better dispersibility.

[0015] The addition amount of reactants in step S2 will affect the size of the SiO2@Fe3O4 microspheres and the thickness of the outer layer of SiO2. When the size of the SiO2@Fe3O4 microspheres is too large, the specific surface area will decrease, resulting in a decrease in adsorption capacity. When the thickness of SiO2 is too low, it will cause the SiO2 to wrap the Fe3O4 microspheres not densely, increasing the contact area between the Fe3O4 microspheres and oxygen. When the thickness of SiO2 is too large, it will cause the adsorption ability of the Fe3O4 microspheres by the magnet to decline.

[0016] As a further optimization of the preparation method of the magnetic molecularly imprinted material for detecting pollutants.

[0017] Preferably, in step S3, the pollutant standard includes one or more of bisphenols, organophosphorus flame retardants, and neonicotinoids. The bisphenol is bisphenol A, the organophosphorus flame retardant is triphenyl phosphate, and the neonicotinoid is imidacloprid.

[0018] Substances with similar properties can also be used to prepare magnetic molecularly imprinted materials in the same way. For example: parabens, paraben metabolites, organophosphorus flame retardants, organophosphorus flame retardants, neonicotinoids, neonicotinoid metabolites, macrolides, chlorophenols, ultraviolet light protectants, anti-aging agents, traditional pesticides pyrethroid insecticides, traditional pesticides phenoxycarboxylic acid herbicides, traditional pesticides organophosphorus insecticides, traditional pesticides triazine herbicides, new pesticides neonicotinoid insecticides.

[0019] The present invention also provides a method for detecting pollutants using a magnetic molecularly imprinted material.

[0020] The technical solution adopted is:

[0021] A method for detecting pollutants using a magnetic molecularly imprinted material, the detection method comprising the following steps:

[0022] S11. Prepare the sample to be tested: Transfer 1 - 5 mL of urine into a glass test tube, add 0.3 - 0.6 mol / mL acetic acid buffer solution, then add 50 μL of 100 mg / mL mixed internal standard solution, and then incubate in a water bath at 37 °C for 6 - 12 h;

[0023] S12. Vortex 0.5 - 1.0 mL of acetonitrile evenly, add 3 - 5 mL of ethyl acetate, ultrasonicate for 30 - 40 min, oscillate for 30 - 40 min, centrifuge at a low - temperature centrifuge (4 °C, 3400 g) for 5 - 8 min, take the supernatant, and repeat twice. Combine the supernatants, blow to dryness, re - dissolve with 200 μL of 50% methanol - water, and filter through a 0.22 μL organic filter membrane to obtain the sample to be tested;

[0024] S13. Take 30 - 60 mg of magnetic molecularly imprinted material in a centrifuge tube, add 3 - 6 mL of methanol, vortex to remove the supernatant, then add the sample to be tested in step S12, oscillate for 2 - 3 min, then separate the magnetic molecularly imprinted material and the solution by a magnet, pour out the solution, and then wash the surface with methanol 2 times. Finally, add 1 - 2 mL of acetonitrile as the eluent, collect the eluent, then dry it with nitrogen, and then dissolve it with chromatographically pure acetonitrile. After ultrasonic treatment and filtration, use high - performance liquid chromatography to detect the concentration of pollutants.

[0025] Preferably, the preparation method of the acetic acid buffer solution in step S11 is as follows:

[0026] Take 3.85 - 4 g of ammonium acetate, add 25 - 30 mL of pure water, then add 3 - 5 mL of glacial acetic acid, make up the volume to 50 - 60 mL with pure water, and finally add 60 - 80 μL of 85000 units / mL β-glucuronidase.

[0027] The beneficial effects of the present invention compared with the prior art are as follows:

[0028] (1) The magnetic molecularly imprinted material prepared by the present invention has better dispersibility. The good dispersibility enables the magnetic molecularly imprinted material to fully contact with pollutants, increasing the chance of interaction, thereby improving the detection sensitivity and enabling the detection of lower concentrations of pesticide residues. The good dispersibility of the material helps to accelerate the mass transfer process, enabling the target to quickly bind to the recognition site, thus shortening the detection time required.

[0029] (2) For the SiO2@Fe3O4 microspheres prepared in the present invention, there is a certain matching ratio between the thickness of the SiO2 shell and the size of the Fe3O4 microspheres, which not only ensures the dense encapsulation of Fe3O4 microspheres by SiO2 but also reduces the influence of the magnet on the attraction of Fe3O4 microspheres. Additionally, the overall size of the SiO2@Fe3O4 microspheres is 100 - 210 nm. The small size of the microspheres and large specific surface area result in a good effect of adsorbing the target.

[0030] (3) The SiO2 on the outer layer of the Fe3O4 microspheres synthesized in the present invention consists of two layers. The inner layer has a dense structure to prevent the Fe3O4 microspheres from being oxidized and losing magnetism. The outer layer of SiO2 has a large number of pores, which can improve its adsorption of the target.

[0031] (4) The magnetic molecularly imprinted material synthesized in the present invention can reduce the dosage of the adsorbent and shorten the separation and enrichment time. Combining it with the high-performance liquid chromatography detection method greatly saves the analysis time and cost. Description of the Drawings

[0032] Figure 1 is a schematic flow chart of the preparation of a magnetic molecularly imprinted material for detecting pollutants and its detection method;

[0033] Figure 2 (a) is a transmission electron microscope photograph of the SiO2@Fe3O4 microspheres synthesized in Example 1, Figure 2 (b) is a Gaussian fitting curve for statistically analyzing the size of Fe3O4 microspheres;

[0034] Figure 3 is the result obtained by a vibrating sample magnetometer for the magnetic molecularly imprinted materials prepared in Comparative Example 1 and Example 1;

[0035] Figure 4It is a bar chart of the adsorption rate of the magnetic molecularly imprinted material to pollutants within 10 minutes in Comparative Examples 1-3 and Examples 1-3;

[0036] Figure 5 It is the recovery rate curve of triphenyl phosphate in Comparative Example 2 and Example 2 under different desorption volumes;

[0037] Figure 6 It is the recovery rate curve of acetamiprid in Comparative Example 3 and Example 3 under different desorption times. Detailed implementation mode

[0038] The present invention will be further described below in conjunction with comparative examples and examples.

[0039] Comparative Example 1

[0040] This comparative example provides a magnetic molecularly imprinted material and a detection method for detecting multiple pollutants, specifically including the following steps:

[0041] S1. 0.4 g of FeCl3·6H2O and 15 mL of deionized water are subjected to a hydrothermal reaction at 120 °C for 8 h. After the reaction, monodisperse Fe2O3 microspheres are obtained by centrifugation and washing;

[0042] S2. The Fe2O3 microspheres in step S1 are dispersed in 30 mL of absolute ethanol, 0.6 mL of tetraethyl orthosilicate and 2 mL of ammonia water are added and reacted for 5 h, then 0.5 mL and 0.2 mL of N-[3-(trimethoxysilyl)propyl]ethylenediamine are added as silicon sources and reacted for 5 h. After the reaction, SiO2-coated Fe2O3 microspheres are obtained by centrifugation, washing and drying. Finally, it is calcined in 3% H2 and 97% N2 at 300 °C for 2 h to obtain SiO2@Fe3O4 powder. Among them, Fe3O4 microspheres are coated with SiO2, the particle size of Fe3O4 is 79.3 nm, and the thickness of the SiO2 outer shell is 11.2 nm;

[0043] S3. 100 mg of imidacloprid standard is placed in a flask, 30 mL of acetonitrile, 4 mL of deionized water and 0.1 mL of methacrylic acid are added and stirred for 3 h, and then 10 mL of the modified SiO2@Fe3O4 microsphere sol in step S3 is added thereto. Then 8 mmol of trimethylolpropane trimethacrylate and 20 mg of 2,2-azobisisobutyronitrile are added and stirred thoroughly for 16 h, and then washed repeatedly by centrifugation with acetonitrile until the imidacloprid standard cannot be detected and then reserved.

[0044] According to the above method, a magnetic molecularly imprinted material for detecting multiple pollutants is obtained.

[0045] Detection method:

[0046] S11. Prepare the sample to be measured: Transfer 1 mL of urine into a glass test tube, add 0.3 mol / mL acetic acid buffer solution, then add 50 μL of 100 mg / mL mixed internal standard solution, and then incubate in a water bath at 37 °C for 6 h;

[0047] S12. Vortex 0.5 mL of acetonitrile evenly, add 3 mL of ethyl acetate, sonicate for 30 min, shake for 30 min, centrifuge at a low-temperature centrifuge (4 °C, 3400 g) for 5 min, take the supernatant, and repeat twice. Combine the supernatants, blow to dryness, re-dissolve with 200 μL of 50% methanol-water, and filter through a 0.22 μL organic filter membrane to obtain the sample to be measured;

[0048] S13. Take 30 mg of magnetic molecularly imprinted material in a centrifuge tube, add 3 mL of methanol and vortex to remove the supernatant, then add the sample to be measured in step S12, shake for 2 min, and then separate the magnetic molecularly imprinted material and the solution by a magnet, pour out the solution, and add methanol to wash the surface twice. Finally, add 1 mL of acetonitrile as the eluent, collect the eluent, then dry it with nitrogen, and then dissolve it with chromatographically pure acetonitrile. After ultrasonic treatment and filtration, use high-performance liquid chromatography to detect the concentration of imidacloprid

[0049] Among them, the preparation method of the acetic acid buffer solution in step S11 is as follows:

[0050] Take 3.85 g of ammonium acetate, add 25 mL of pure water, then add 3 mL of glacial acetic acid, then make up the volume to 50 mL with pure water, and finally add 60 μL of 85000 units / mL β-glucuronidase.

[0051] Comparative Example 2

[0052] This comparative example provides a magnetic molecularly imprinted material and a detection method for detecting multiple pollutants, which specifically include the following steps:

[0053] S1. Hydrothermal react 1.2 g of FeCl3·6H2O, 0.1 g of PVP and 30 mL of deionized water at 200 °C for 12 h. After the reaction, obtain monodisperse Fe2O3 microspheres by centrifugation and washing;

[0054] S2. Disperse the Fe2O3 microspheres in step S1 in 60 mL of absolute ethanol, add 2 mL of tetraethyl orthosilicate and 4 mL of ammonia water and react for 12 h. Then add 1 mL of N-[3-(trimethoxysilyl)propyl]ethylenediamine and 1 mL as the silicon source and react for 12 h. After the reaction, obtain the Fe2O3 microspheres encapsulated with SiO2 by centrifugation, washing and drying. Finally, calcine at 400 °C in 5% H2 and 95% N2 for 3 h to obtain the SiO2@Fe3O4 powder. Among them, the Fe3O4 microspheres are encapsulated with SiO2, the particle size of Fe3O4 is 154.5 nm, and the thickness of the SiO2 shell is 32.5 nm;

[0055] S3. Place 300 mg of triphenyl phosphate standard in a flask, add 100 mL of acetonitrile, 12 mL of deionized water and 0.5 mL of methacrylic acid and stir for 5 h. Then add 0.3 g of SiO2@Fe3O4 microsphere sol. Then add 30 mmol of trimethylolpropane trimethacrylate and 60 mg of 2,2-azobisisobutyronitrile and stir well for 20 h. Then wash repeatedly with acetonitrile by centrifugation until the triphenyl phosphate standard cannot be detected and set aside.

[0056] According to the above method, a magnetic molecularly imprinted material for detecting multiple pollutants is obtained.

[0057] Detection method:

[0058] S11. Prepare the sample to be tested: Transfer 3 mL of urine into a glass test tube, add 0.4 mol / mL acetic acid buffer solution, and then add 50 μL of 100 mg / mL mixed internal standard solution. Then incubate in a 37 °C water bath for 8 h;

[0059] S12. Vortex 0.8 mL of acetonitrile evenly, add 4 mL of ethyl acetate, ultrasonicate for 35 min, oscillate for 35 min, centrifuge at a low-temperature centrifuge (4 °C, 3400 g) for 6 min, take the supernatant, and repeat twice. Combine the supernatants, blow to dryness, re-dissolve with 200 μL of 50% methanol-water, and filter through a 0.22 μL organic filter membrane to obtain the sample to be tested;

[0060] S13. Take 40 mg of the magnetic molecularly imprinted material in a centrifuge tube, add 4 mL of methanol and vortex to remove the supernatant. Then add the sample to be tested in step S12, shake for 2.5 min, then separate the magnetic molecularly imprinted material and the solution by a magnet, pour out the solution, and then wash the surface with methanol 3 times. Finally, add 2 mL of acetonitrile as the eluent, collect the eluent, then dry it with nitrogen, re-dissolve it with chromatographically pure acetonitrile, and after ultrasonic treatment and filtration, use high performance liquid chromatography to detect the concentration of triphenyl phosphate.

[0061] Among them, the preparation method of the acetic acid buffer solution in step S11 is as follows:

[0062] Take 3.9 g of ammonium acetate, add 27 mL of pure water, then add 4 mL of glacial acetic acid, then make up the volume to 55 mL with pure water, and finally add 70 μL of 85000 units / mL β-glucuronidase.

[0063] Comparative Example 3

[0064] This comparative example provides a magnetic molecularly imprinted material for detecting multiple pollutants and its preparation method, which specifically includes the following steps:

[0065] S1. Hydrothermal react 0.8 g of FeCl3·6H2O, 0.05 g of PVP and 20 mL of deionized water at 260 °C for 10 h. After the reaction, obtain monodisperse Fe2O3 microspheres by centrifugation and washing.

[0066] S2. Disperse the Fe2O3 microspheres in step S1 in 40 mL of absolute ethanol, add 1 mL of tetraethyl orthosilicate and 3 mL of ammonia water and react for 8 h, then add 0.7 mL and 0.5 mL of N-[3-(trimethoxysilyl)propyl]ethylenediamine as the silicon source and react for 8 h. After the reaction, obtain SiO2-coated Fe2O3 microspheres by centrifugation, washing and drying. Finally, calcine in 4% H2 and 96% N2 at 350 °C for 2.5 h to obtain SiO2@Fe3O4 powder. Among them, SiO2 coats Fe3O4 microspheres, the particle size of Fe3O4 is 122.5 nm, and the thickness of the SiO2 shell is 24.3 nm.

[0067] S3. Place 200 mg of bisphenol A standard in a flask, add 60 mL of acetonitrile, 8 mL of deionized water and 0.3 mL of methacrylic acid and stir for 4 h, then add 0.2 g of SiO2@Fe3O4 microsphere sol. Then add 15 mmol of trimethylolpropane trimethacrylate and 40 mg of 2,2-azobisisobutyronitrile and stir thoroughly for 18 h, then wash by centrifugation and repeatedly wash with acetonitrile until the bisphenol A standard cannot be detected and then set aside.

[0068] According to the above method, a magnetic molecularly imprinted material for detecting multiple pollutants is obtained.

[0069] Detection method:

[0070] S11. Prepare the sample to be tested: Transfer 5 mL of urine into a glass test tube, add 0.6 mol / mL acetic acid buffer solution, then add 50 μL of 100 mg / mL mixed internal standard solution, and then incubate in a 37 °C water bath for 12 h.

[0071] S12. Vortex 1.0 mL of acetonitrile evenly, add 5 mL of ethyl acetate, ultrasonicate for 40 min, oscillate for 40 min, centrifuge at a low-temperature centrifuge (4 °C, 3400 g) for 8 min, take the supernatant, and repeat twice. Combine the supernatants, blow to dryness, redissolve with 200 μL of 50% methanol-water, filter through a 0.22 μL organic filter membrane to obtain the sample to be tested;

[0072] S13. Take 60 mg of magnetic molecularly imprinted material in a centrifuge tube, add 6 mL of methanol, vortex to remove the supernatant, then add the sample to be tested in step S12, oscillate for 3 min, then separate the magnetic molecularly imprinted material and the solution by a magnet, pour out the solution, and add methanol to wash the surface twice. Finally, add 2 mL of acetonitrile as the eluent, collect the eluent, then dry it with nitrogen, redissolve it with chromatographically pure acetonitrile, and after ultrasonic treatment and filtration, use high-performance liquid chromatography to detect the concentration of bisphenol A.

[0073] Among them, take 4 g of ammonium acetate, add 30 mL of pure water, then add 5 mL of glacial acetic acid, make up the volume to 60 mL with pure water, and finally add 80 μL of 85000 units / mL β-glucuronidase.

[0074] Example 1

[0075] This example provides a magnetic molecularly imprinted material and a detection method for detecting multiple pollutants, which specifically include the following steps:

[0076] S1. Hydrothermally react 0.4 g of FeCl3·6H2O and 15 mL of deionized water at 120 °C for 8 h. After the reaction, obtain monodisperse Fe2O3 microspheres by centrifugation and washing;

[0077] S2. Disperse the Fe2O3 microspheres in step S1 in 30 mL of absolute ethanol, add 0.6 mL of tetraethyl orthosilicate and 2 mL of ammonia water and react for 5 h, then add 0.5 mL and 0.2 mL of N-[3-(trimethoxysilyl)propyl]ethylenediamine as the silicon source and react for 5 h. After the reaction, obtain SiO2-coated Fe2O3 microspheres by centrifugation, washing and drying. Finally, calcine in 3% H2 and 97% N2 at 300 °C for 2 h to obtain SiO2@Fe3O4 powder. Among them, SiO2 coats Fe3O4 microspheres, the particle size of Fe3O4 is 79.3 nm, and the thickness of the SiO2 shell is 11.2 nm;

[0078] S3. Add 0.2 g of the SiO2@Fe3O4 powder obtained in step S1 into 5 mL of an aqueous methanesulfonic acid solution with a mass ratio of 0.2 wt%, stir at 80 °C for 4 h, then obtain the SiO2@Fe3O4 powder by centrifugation, add it into 30 mL of absolute ethanol, then add 0.3 mL of ammonia water and 0.1 mL of silane coupling agent KH-570, and stir at 30 °C for 5 h to obtain a modified SiO2@Fe3O4 microsphere sol;

[0079] S4. Place 100 mg of imidacloprid standard in a flask, add 30 mL of acetonitrile, 4 mL of deionized water and 0.1 mL of methacrylic acid, stir for 3 h, and then add 10 mL of the modified SiO2@Fe3O4 microsphere sol obtained in step S2. Then add 8 mmol of trimethylolpropane trimethacrylate and 20 mg of 2,2'-azobisisobutyronitrile in sequence, stir thoroughly for 16 h, and then wash repeatedly by centrifugation with acetonitrile until no imidacloprid standard can be detected and set aside.

[0080] According to the above method, a magnetic molecularly imprinted material for detecting multiple pollutants is obtained.

[0081] Detection method:

[0082] S11. Prepare the sample to be tested: Transfer 1 mL of urine into a glass test tube, add 0.3 mol / mL acetic acid buffer solution, and then add 50 μL of a 100 mg / mL mixed internal standard solution, and then incubate in a 37 °C water bath for 6 h;

[0083] S12. Vortex 0.5 mL of acetonitrile evenly, add 3 mL of ethyl acetate, ultrasonicate for 30 min, oscillate for 30 min, centrifuge at a low-temperature centrifuge (4 °C, 3400 g) for 5 min, take the supernatant, and repeat twice. Combine the supernatants, blow to dryness, re-dissolve with 200 μL of 50% methanol water, and filter through a 0.22 μL organic filter membrane to obtain the sample to be tested;

[0084] S13. Take 30 mg of the magnetic molecularly imprinted material in a centrifuge tube, add 3 mL of methanol, vortex to remove the supernatant, then add the sample to be tested in step S12, oscillate for 2 min, then separate the magnetic molecularly imprinted material and the solution by a magnet, pour out the solution, and then wash the surface with methanol twice. Finally, add 1 mL of acetonitrile as the eluent, collect the eluent, then dry it with nitrogen, re-dissolve it with chromatographically pure acetonitrile, and after ultrasonic treatment and filtration, use high-performance liquid chromatography to detect the concentration of imidacloprid

[0085] Among them, the preparation method of the acetic acid buffer solution in step S11 is as follows:

[0086] Take 3.85 g of ammonium acetate, add 25 mL of pure water, then add 3 mL of glacial acetic acid, and then make up the volume to 50 mL with pure water. Finally, add 60 μL of β-glucuronidase at 85000 units / mL.

[0087] Example 2

[0088] This example provides a magnetic molecularly imprinted material and a detection method for detecting multiple pollutants, which specifically include the following steps:

[0089] S1. Hydrothermal react 1.2 g of FeCl3·6H2O, 0.1 g of PVP and 30 mL of deionized water at 200 °C for 12 h. After the reaction is completed, obtain monodisperse Fe2O3 microspheres by centrifugation and washing.

[0090] S2. Disperse the Fe2O3 microspheres in step S1 in 60 mL of absolute ethanol, add 2 mL of tetraethyl orthosilicate and 4 mL of ammonia water and react for 12 h. Then add 1 mL of N-[3-(trimethoxysilyl)propyl]ethylenediamine as the silicon source and react for 12 h. After the reaction is completed, obtain Fe2O3 microspheres wrapped with SiO2 by centrifugation, washing and drying. Finally, calcine in 5% H2 and 95% N2 at 400 °C for 3 h to obtain SiO2@Fe3O4 powder. Among them, Fe3O4 microspheres are wrapped with SiO2, the particle size of Fe3O4 is 154.5 nm, and the thickness of the SiO2 shell is 32.5 nm.

[0091] S3. Add 1 g of the SiO2@Fe3O4 powder obtained in step S1 to 15 mL of an aqueous methanesulfonic acid solution with a mass ratio of 1 wt%, stir at 120 °C for 4 h, then obtain the SiO2@Fe3O4 powder by centrifugation, and then add it to 100 mL of absolute ethanol. Then add 2 mL of ammonia water and 1 mL of silane coupling agent KH-570 and stir at 55 °C for 10 h to obtain a modified SiO2@Fe3O4 microsphere sol.

[0092] S4. Place 300 mg of triphenyl phosphate standard in a flask, add 100 mL of acetonitrile, 12 mL of deionized water and 0.5 mL of methacrylic acid and stir for 5 h. Then add 50 mL of the modified SiO2@Fe3O4 microsphere sol obtained in step S2. Then add 30 mmol of trimethylolpropane trimethacrylate and 60 mg of 2,2-azobisisobutyronitrile and stir thoroughly for 20 h. Then wash by centrifugation and repeatedly wash with acetonitrile until the triphenyl phosphate standard cannot be detected and then set aside.

[0093] According to the above method, a magnetic molecularly imprinted material for detecting multiple pollutants is obtained.

[0094] Detection method:

[0095] S11. Prepare the sample to be tested: Transfer 3 mL of urine into a glass test tube, add 0.4 mol / mL acetic acid buffer solution, then add 50 μL of 100 mg / mL mixed internal standard solution, and then incubate in a water bath at 37 °C for 8 h;

[0096] S12. Vortex 0.8 mL of acetonitrile evenly, add 4 mL of ethyl acetate, ultrasonicate for 35 min, oscillate for 35 min, centrifuge at a low-temperature centrifuge (4 °C, 3400 g) for 6 min, take the supernatant, and repeat twice. Combine the supernatants, blow to dryness, re-dissolve with 200 μL of 50% methanol-water, and filter through a 0.22 μL organic filter membrane to obtain the sample to be tested;

[0097] S13. Take 40 mg of magnetic molecularly imprinted material in a centrifuge tube, add 4 mL of methanol and vortex to remove the supernatant, then add the sample to be tested in step S12, oscillate for 2.5 min, then separate the magnetic molecularly imprinted material and the solution by a magnet, pour out the solution, and then add methanol to wash the surface 3 times. Finally, add 2 mL of acetonitrile as the eluent, collect the eluent, then dry it with nitrogen, and then dissolve it with chromatographically pure acetonitrile. After ultrasonic treatment and filtration, use high-performance liquid chromatography to detect the concentration of triphenyl phosphate.

[0098] Among them, the preparation method of the acetic acid buffer solution in step S11 is as follows:

[0099] Take 3.9 g of ammonium acetate, add 27 mL of pure water, then add 4 mL of glacial acetic acid, then make up the volume to 55 mL with pure water, and finally add 70 μL of 85000 units / mL β-glucuronidase.

[0100] Example 3

[0101] This example provides a magnetic molecularly imprinted material and a detection method for detecting multiple pollutants, specifically including the following steps:

[0102] S1. Hydrothermal react 0.8 g of FeCl3·6H2O, 0.05 g of PVP and 20 mL of deionized water at 260 °C for 10 h. After the reaction is completed, obtain monodisperse Fe2O3 microspheres by centrifugation and washing;

[0103] S2. Disperse the Fe2O3 microspheres in step S1 in 40 mL of absolute ethanol, add 1 mL of tetraethyl orthosilicate and 3 mL of ammonia water and react for 8 h, then add 0.7 mL and 0.5 mL of N-[3-(trimethoxysilyl)propyl]ethylenediamine as the silicon source and react for 8 h. After the reaction, obtain the Fe2O3 microspheres wrapped with SiO2 by centrifugation, washing and drying. Finally, calcine at 350 °C in 4% H2 and 96% N2 for 2.5 h to obtain the SiO2@Fe3O4 powder. Among them, the Fe3O4 microspheres are wrapped with SiO2, the particle size of Fe3O4 is 122.5 nm, and the thickness of the SiO2 shell is 24.3 nm;

[0104] S2. Add 0.5 g of the SiO2@Fe3O4 powder obtained in step S1 to 10 mL of an aqueous methanesulfonic acid solution with a mass ratio of 0.5 wt%, stir at 100 °C for 4 h, then obtain the SiO2@Fe3O4 powder by centrifugation, add it to 60 mL of absolute ethanol, then add 1 mL of ammonia water and 0.5 mL of the silane coupling agent KH-570 and stir at 40 °C for 6 h to obtain the modified SiO2@Fe3O4 microsphere sol;

[0105] S3. Place 200 mg of bisphenol A standard in a flask, add 60 mL of acetonitrile, 8 mL of deionized water and 0.3 mL of methacrylic acid and stir for 4 h, then add 30 mL of the modified SiO2@Fe3O4 microsphere sol in step S2. Then add 15 mmol of trimethylolpropane trimethacrylate and 40 mg of 2,2-azobisisobutyronitrile and stir thoroughly for 18 h, then wash repeatedly by centrifugation with acetonitrile until the bisphenol A standard cannot be detected and set aside.

[0106] According to the above method, a magnetic molecularly imprinted material for detecting multiple pollutants is obtained.

[0107] Detection method:

[0108] S11. Prepare the sample to be tested: Transfer 5 mL of urine into a glass test tube, add 0.6 mol / mL acetic acid buffer solution, then add 50 μL of the 100 mg / mL mixed internal standard solution, and then incubate in a 37 °C water bath for 12 h;

[0109] S12. Vortex 1.0 mL of acetonitrile evenly, add 5 mL of ethyl acetate, ultrasonicate for 40 min, oscillate for 40 min, centrifuge at a low-temperature centrifuge (4 °C, 3400 g) for 8 min, take the supernatant, and repeat twice. Combine the supernatants, blow to dryness, re-dissolve with 200 μL of 50% methanol water, and filter through a 0.22 μL organic filter membrane to obtain the sample to be tested;

[0110] S13. Take 60 mg of the magnetic molecularly imprinted material in a centrifuge tube, add 6 mL of methanol, vortex to remove the supernatant, then add the sample to be tested in step S12, shake for 3 min, then separate the magnetic molecularly imprinted material and the solution by a magnet, pour out the solution, and add methanol to wash the surface twice. Finally, add 2 mL of acetonitrile as the eluent, collect the eluent, then dry it with nitrogen, add chromatographically pure acetonitrile to dissolve it, after ultrasonic treatment and filtration, use high performance liquid chromatography to detect the concentration of bisphenol A.

[0111] Among them, take 4 g of ammonium acetate, add 30 mL of pure water, then add 5 mL of glacial acetic acid, and then make up the volume to 60 mL with pure water. Finally, add 80 μL of 85000 units / mL β-glucuronidase.

[0112] Figure 1 It is a process schematic diagram for preparing a magnetic molecularly imprinted material for detecting pollutants and its detection method.

[0113] Figure 2 (a) is a transmission electron microscope photograph of the SiO2@Fe3O4 microspheres synthesized in Example 1. It can be seen that the Fe3O4 microspheres are wrapped by SiO2. Figure 2 (b) is a Gaussian fitting curve for statistically analyzing the size of the Fe3O4 microspheres. It is calculated that the particle size of the Fe3O4 microspheres is 79.3 nm. The thickness of the SiO2 shell is about 11.2 nm obtained by the same statistical method. In addition, it can be seen that the SiO2@Fe3O4 microspheres have good dispersibility. This will increase their specific surface area, thereby improving their ability to adsorb the target substance.

[0114] Figure 3 It is the result obtained by a vibrating sample magnetometer for the magnetic molecularly imprinted materials prepared in Comparative Example 1 and Example 1. Both materials are paramagnetic, and the example with better dispersion has stronger magnetism.

[0115] Figure 4 It is a bar chart of the adsorption rates of the magnetic molecularly imprinted materials for pollutants within 10 min in Comparative Examples 1-3 and Examples 1-3. It can be seen that the adsorption rates in Examples 1-3 are higher than those in Comparative Examples 1-3, which shows that the dispersion of the magnetic molecularly imprinted material directly affects its adsorption effect. In addition, the amount of the magnetic molecularly imprinted material also affects the adsorption rate. The more the magnetic molecularly imprinted material, the better the adsorption effect.

[0116] Figure 5 It is the recovery rate curve of triphenyl phosphate in Comparative Example 2 and Example 2 under different elution volumes. It can be seen that Example 2 only needs less eluent to recover triphenyl phosphate to the greatest extent. This is because the magnetic molecularly imprinted material with better dispersion has a larger contact area, and only less eluent is needed to make the target substance fall off the magnetic molecularly imprinted material.

[0117] Figure 6 It is the recovery rate curve of bisphenol A for Comparative Example 3 and Example 3 at different elution times. It can be seen that the elution time of Example 3 is shorter than that of Comparative Example 3, which indicates that the magnetic molecularly imprinted material with better dispersibility has a better elution effect.

[0118] From the experimental results of the above Comparative Examples 1-3 and Examples 1-3, it can be shown that the present invention provides a magnetic molecularly imprinted material and a detection method for detecting multiple pollutants.

[0119] Those skilled in the art should understand that the above are only several specific embodiments of the present invention, rather than all embodiments. It should be pointed out that many modifications and improvements can be made by those of ordinary skill in the art, and all modifications or improvements that do not exceed the scope of the claims shall be regarded as the protection scope of the present invention.

Claims

1. A magnetic molecular imprinting material for detecting multiple pollutants, comprising: Magnetic Fe3O4 microspheres, SiO2 shells and molecular imprinting templates, characterized in that the size of the magnetic Fe3O4 microspheres is 79.3-154.5nm, the SiO2 shell is divided into two layers, the outer layer contains a large number of pores, and the inner layer has a dense structure. The overall thickness is 11.2-32.5nm, wherein the SiO2 shell wraps the magnetic Fe3O4 microspheres, and the molecular imprinting template is attached to the surface of the SiO2 shell.

2. A method for preparing a magnetic molecular imprinted material according to claim 1, characterized in that: The following steps are involved: S1, 0.4-1.2 g FeCl3·6H2O, 0-0.1 g PVP and 15-30 mL deionized water were subjected to hydrothermal reaction at 120-200 °C for 8-12 h, and monodispersed Fe2O3 microspheres were obtained by centrifugation and washing after the reaction. S2, dispersing the Fe2O3 microspheres in step S1 in 30-60 mL of anhydrous ethanol, adding 0.6-2 mL of tetraethyl orthosilicate and 2-4 mL of ammonia water to react for 5-12 h, then adding 0.5-1 mL and 0.2-1 mL of N-[3-(trimethoxysilyl)propyl]ethylenediamine as silicon sources, reacting for 5-12 h, and after the reaction, obtaining SiO2-coated Fe2O3 microspheres by centrifugation, washing, and drying, and finally calcining at 300-400° C. in 3-5% H2 and 97-95% N2 for 2-3 h to obtain SiO2@Fe3O4 powder; S3, adding 0.2-1 g of the SiO2@Fe3O4 powder obtained in step S2 to 5-15 mL of a 0.2-1 wt% methanesulfonic acid aqueous solution, stirring at 80-120° C. for 4 h, then centrifuging to obtain SiO2@Fe3O4 powder, adding it to 30-100 mL of anhydrous ethanol, then adding 0.3-2 mL of ammonia water and 0.1-1 mL of a silane coupling agent KH-570, stirring at 30-55° C. for 5-10 h, to obtain a modified SiO2@Fe3O4 microsphere sol; S4. Place 100-300 mg of the pollutant standard in a flask, add 30-100 mL of acetonitrile, 4-12 mL of deionized water and 0.1-0.5 mL of methacrylic acid and stir for 3-5 hours, then add 10-50 mL of the modified SiO2@Fe3O4 microsphere sol in step S3, then add 8-30 mmol of trimethylolpropane trimethacrylate and 20-60 mg of 2,2-azobisisobutyronitrile in sequence and stir thoroughly for 16-20 hours, then wash repeatedly with acetonitrile by centrifugation until the pollutant standard is undetectable and set aside.

3. The method for preparing a magnetic molecular imprinted material for detecting pollutants according to claim 2, characterized in that: The pollutant standard in step S3 includes one or more of bisphenols, organophosphorus flame retardants and neonicotinoids, wherein the bisphenol is bisphenol A, the organophosphorus flame retardant is triisostyrene phosphate, and the neonicotinoid is imidacloprid.

4. A method for detecting pollutants using the magnetic molecular imprinting material according to claim 1, characterized in that: The following steps are involved: S11. Prepare the sample to be tested: transfer 1-5 mL of urine into a glass test tube, add 0.3-0.6 mol / mL acetic acid buffer, then add 50 μL of 100 mg / mL mixed internal standard solution, and then incubate in a 37°C water bath for 6-12 h; S12, vortex 0.5-1.0 mL of acetonitrile evenly, add 3-5 mL of ethyl acetate, ultrasonicate for 30-40 min, oscillate for 30-40 min, centrifuge in a low-temperature centrifuge (4°C, 3400g) for 5-8 min, take the supernatant, repeat twice, combine the supernatants, blow to dryness, re-dissolve with 200 μL of 50% methanol water, filter through 0.22 μL of organic filter membrane, and obtain the sample to be tested; S13, take 30-60 mg of magnetic molecular imprinting material into a centrifuge tube, add 3-6 mL of methanol, vortex to remove the supernatant, then add the sample to be tested in step S12, shake for 2-3 minutes, then separate the magnetic molecular imprinting material and the solution by a magnet, pour out the solution, add methanol to wash the surface twice, and finally add 1-2 mL of acetonitrile as eluent, collect the eluent, and then blow dry with nitrogen, then add chromatographic pure acetonitrile to dissolve, after ultrasonic treatment and filtration, use high performance liquid chromatography to detect the concentration of pollutants.

5. The method for detecting pollutants using magnetic molecular imprinting materials according to claim 4, characterized in that: The preparation method of the acetate buffer in step S11 is as follows: Take 3.85-4 g of ammonium acetate, add 25-30 mL of purified water, then add 3-5 mL of glacial acetic acid, and then make up to 50-60 mL with purified water, and finally add 60-80 μL of 85000 units / mL β-glucuronidase.

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