Magnetic molecularly imprinted material for detecting various pollutants and detection method

Abstract

The present application belongs to the field of biomedical detection, and particularly relates to a magnetic molecularly imprinted material for detecting various pollutants and a detection method. The present application coats magnetic Fe3O4 material with inorganic SiO2, and then coats the inorganic SiO2 with a layer of organic-inorganic hybrid SiO2 nanoparticles. Through high-temperature treatment, pores are formed on the surface of the organic-inorganic hybrid SiO2 nanoparticles, thereby improving the adsorption of target objects. Then, the SiO2@Fe3O4 material with good dispersity is obtained through activation and dispersion treatment. Finally, a molecular imprinting layer is introduced on the surface of the modified magnetic SiO2@Fe3O4 material to form the magnetic molecularly imprinted material. The material is combined with solid-phase extraction technology to realize the extraction of pollutants in urine. Then, the pollutants are detected through high-performance liquid chromatography. The method effectively reduces the interference of impurities and improves the accuracy of quantification, so that the detection of trace pollutants is more sensitive.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of biomedical detection, and particularly relates to a magnetic molecularly imprinted material for detecting various pollutants and a detection method. BACKGROUND

[0002] Pesticides, as an efficient insecticide, have been widely used in agricultural production. With the widespread use of pollutants, many problems have been exposed. Because pollutants have a long biological half-life in the environment, there are trace amounts of pollutants in soil, water sources, etc. Although most of the pollutants do not directly pollute the water source, they will enter the water source through rainwater washing, soil penetration, etc. after being used in crops. The content of pollutants in the Yangtze River and other surface water 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 food chain, thereby causing potential harm to human health. Trace amounts of pesticide residues can often be detected in human urine. For example, neonicotinoids, traditional pesticide pyrethroid insecticides, phenoxy acid herbicides, organophosphorus insecticides, triazine herbicides, etc. Therefore, the detection of pollutants in human urine is of great significance.

[0003] Common methods for detecting pollutants include high performance liquid chromatography, enzyme-linked immunosorbent assay, surface-enhanced Raman spectroscopy, etc. However, human urine contains many impurities and the content of pollutants is low, so the sample to be detected is generally 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 target substance to be detected and separate it from impurities.

[0004] The key to efficient enrichment of the target substance to be detected lies in the adsorption of the adsorbent. The molecular imprinting technology combines the target substance to be detected with the molecular imprinting host, which has the advantage of adsorbing the target substance from a complex matrix. The magnetic molecular imprinting technology can more effectively enrich the target substance and easily separate it from impurities. Fe3O4 nanoparticles are common magnetic materials, but they have poor dispersibility and are easily oxidized, which reduces their adsorption performance of the target substance. SUMMARY

[0005] The application provides a magnetic molecular imprinting material for detecting various pollutants, which is composed of SiO2@Fe3O4 microspheres, the SiO2 microspheres are divided into two layers, the middle layer is dense and can prevent Fe3O4 from being oxidized to lose magnetism, and the outer layer of SiO2 has a large number of pores to increase the specific surface area and thus increase the adsorption of the target object.

[0006] The application solves the technical problems by adopting the technical solutions as follows:

[0007] The application provides a magnetic molecular imprinting material for detecting various pollutants, which is composed of SiO2@Fe3O4 microspheres, the SiO2 microspheres are divided into two layers, the middle layer is dense and can prevent Fe3O4 from being oxidized to lose magnetism, and the outer layer of SiO2 has a large number of pores to increase the specific surface area and thus increase the adsorption of the target object.

[0008] The outer layer of SiO2 of the Fe3O4 microspheres is composed of two layers, the inner layer has a dense structure and can prevent Fe3O4 microspheres from being oxidized to lose magnetism, and the outer layer of SiO2 has a large number of pores to increase the adsorption of the target object.

[0009] The application further provides a preparation method of the magnetic molecular imprinting material for detecting various pollutants, and the preparation method comprises the following steps:

[0010] S1, 0.4-1.2g of FeCl3·6H2O, 0-0.1g of PVP and 15-30mL of deionized water are subjected to hydrothermal reaction at 120-200 DEG C for 8-12h, and then monodispersed Fe2O3 microspheres are obtained by centrifugation and washing after the reaction;

[0011] S2, the Fe2O3 microspheres in step S1 are dispersed in 30-60mL of anhydrous ethanol, 0.6-2mL of tetraethyl orthosilicate and 2-4mL of ammonia are added and reacted for 5-12h, then 0.5-1mL of N-[3-(trimethoxysilyl)propyl]ethylenediamine and 0.2-1mL of N-[3-(trimethoxysilyl)propyl]ethylenediamine are added as a silicon source and reacted for 5-12h, and then SiO2-coated Fe2O3 microspheres are obtained by centrifugation, washing and drying after the reaction; finally, the SiO2@Fe3O4 powder is obtained by calcining at 300-400 DEG C for 2-3h in 3-5% H2 and 97-95% N2;

[0012] S3, 0.2-1 g of SiO2@Fe3O4 powder obtained in step S2 is added to 5-15 mL of a 0.2-1 wt% methanesulfonic acid aqueous solution, stirred at 80-120°C for 4 h, and then SiO2@Fe3O4 powder is obtained by centrifugation, which is then added to 30-100 mL of anhydrous ethanol, followed by the addition of 0.3-2 mL of ammonia water and 0.1-1 mL of silane coupling agent KH-570, and stirring at 30-55°C for 5-10 h to obtain modified SiO2@Fe3O4 microsphere sol;

[0013] S4, 100-300 mg of a contaminant standard is placed in a flask, followed by the addition of 30-100 mL of acetonitrile, 4-12 mL of deionized water, and 0.1-0.5 mL of methacrylic acid, and stirring for 3-5 h, followed by the addition of 10-50 mL of the modified SiO2@Fe3O4 microsphere sol of step S3. Then 8-30 mmol of trimethylolpropane trimethacrylate and 20-60 mg of 2,2-azobisisobutyronitrile are sequentially added, and stirring is performed for 16-20 h, followed by washing with acetonitrile by centrifugation until the contaminant standard is not detected, and then the product is reserved.

[0014] In step S2, two different SiO2 shells are synthesized by two different hydrolysis methods, the inner layer has a dense structure, preventing the Fe3O4 microspheres from being oxidized and thus losing magnetic properties. The outer layer of SiO2 is treated at high temperature to form a large number of pores, which can improve the adsorption of the target object. In addition, the SiO2@Fe3O4 powder is obtained by H2 reduction at high temperature, and the high temperature conditions cause the SiO2@Fe3O4 microspheres to agglomerate, making it difficult to disperse. In step S3, the surface of the SiO2 shell is treated with methanesulfonic acid, so that the SiO2 surface has a large number of active hydroxyl groups. Then, modification is performed with silane coupling agent KH-570 to improve the dispersibility.

[0015] The amount of reactant added in step S2 affects 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 is reduced, resulting in a decrease in adsorption capacity. When the thickness of SiO2 is too low, the SiO2 does not wrap the Fe3O4 microspheres densely, increasing the contact surface of the Fe3O4 microspheres with oxygen. When the thickness of SiO2 is too large, the adsorption capacity of the Fe3O4 microspheres by a magnet is reduced.

[0016] Further preferred is the method for preparing a magnetic molecularly imprinted material for detecting contaminants.

[0017] Preferably, the contaminant standard in step S3 includes one or more of bisphenols, organophosphorus flame retardants, and neonicotinoids, the bisphenols are bisphenol A, the organophosphorus flame retardants are triphenyl phosphate, and the neonicotinoids are imidacloprid.

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

[0019] The application also provides a method for detecting contaminants by using magnetic molecularly imprinted materials.

[0020] The technical solutions adopted are as follows:

[0021] A method for detecting contaminants by using magnetic molecularly imprinted materials, the detection method comprising the following steps:

[0022] S11, preparing a sample to be tested: 1-5 mL of urine is moved into a glass test tube, 0.3-0.6 mol / mL of acetic acid buffer is added, 50 μL of a mixed internal standard solution of 100 mg / mL is added, and then the mixture is incubated in a 37℃ water bath for 6-12 hours;

[0023] S12, 0.5-1.0 mL of acetonitrile is vortexed uniformly, 3-5 mL of ethyl acetate is added, ultrasonic treatment is performed for 30-40 minutes, oscillation is performed for 30-40 minutes, and then low-temperature centrifugation (4℃, 3400g) is performed for 5-8 minutes; the supernatant is taken, and the operation is repeated twice. The supernatants are combined, dried by blowing, re-dissolved with 200 μL of 50% methanol water, filtered through a 0.22 μL organic filter membrane, and a sample to be tested is obtained;

[0024] S13, 30-60 mg of magnetic molecularly imprinted material is taken in a centrifuge tube, 3-6 mL of methanol is added to vortex and remove the supernatant, and then the sample to be tested in step S12 is added, oscillated for 2-3 minutes, and then the magnetic molecularly imprinted material and the solution are separated by a magnet, the solution is discarded, and the surface is washed twice with methanol. Finally, 1-2 mL of acetonitrile is added as an eluent, the eluent is collected, dried by blowing with nitrogen, dissolved with chromatographically pure acetonitrile, treated by ultrasonic treatment, filtered, and then the concentration of the contaminant is detected by using high performance liquid chromatography.

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

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

[0027] The present application has the following advantages over the prior art:

[0028] (1) The magnetic molecularly imprinted material prepared by the present application has better dispersibility, and the good dispersibility enables the magnetic molecularly imprinted material to fully contact with pollutants, increases the interaction opportunities, thereby improving the detection sensitivity and enabling detection of lower concentration of pesticide residues.

[0029] (2) The SiO2@Fe3O4 microspheres prepared in the present application have a certain matching ratio between the thickness of the SiO2 shell and the size of the Fe3O4 microspheres, which ensures that the SiO2 densely wraps the Fe3O4 microspheres and reduces the influence of the magnet on the attraction of the Fe3O4 microspheres. In addition, the size of the whole SiO2@Fe3O4 microspheres is 100-210nm, and the microspheres have a small size and a large specific surface area, and have a good effect of adsorbing target objects.

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

[0031] (4) The magnetic molecularly imprinted material synthesized in the present application can reduce the amount of adsorbent and shorten the time of separation and enrichment. Combined with the high performance liquid chromatography detection method, the analysis time and cost are greatly saved. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a flowchart of the preparation of the magnetic molecularly imprinted material for detecting pollutants and the detection method thereof;

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

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

[0035] Figure 4is a column chart of the adsorption rate of the magnetic molecularly imprinted material in 10 min on the pollutants in Comparative Example 1-3 and Example 1-3;

[0036] Figure 5 is a recovery rate curve of triphenyl phosphate at different elution volumes in Comparative Example 2 and Example 2;

[0037] Figure 6 is a recovery rate curve of acetamiprid at different elution times in Comparative Example 3 and Example 3. DETAILED DESCRIPTION

[0038] The application will be further described below in combination with the comparative examples and examples.

[0039] Comparative Example 1

[0040] The present comparative example provides a magnetic molecularly imprinted material and a detection method for detecting a plurality of pollutants, specifically comprising the following steps:

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

[0042] S2, the Fe2O3 microspheres in step S1 are dispersed in 30mL of anhydrous ethanol, 0.6mL of tetraethyl orthosilicate and 2mL of ammonia water are added and reacted for 5h, then 0.5mL and 0.2mL of N-[3-(trimethoxysilyl)propyl]ethylenediamine are added as a silicon source and reacted for 5h, and after the reaction is completed, SiO2-coated Fe2O3 microspheres are obtained by centrifugation, washing and drying. Finally, the SiO2@Fe3O4 powder is obtained by calcining at 300℃ for 2h in 3% H2 and 97% N2. The SiO2-coated Fe3O4 microspheres, the particle size of Fe3O4 is 79.3nm, and the thickness of SiO2 shell is 11.2nm;

[0043] S3, 100mg of imidacloprid standard is placed in a flask, 30mL of acetonitrile, 4mL of deionized water and 0.1mL of methacrylic acid are added and stirred for 3h, 10mL of modified SiO2@Fe3O4 microspheres sol in step S3 are added to it. Then 8mmol of trimethylolpropane trimethylacrylate and 20mg of 2,2-azobis isobutyronitrile are added in turn and stirred for 16h, then washed by centrifugation and repeatedly washed with acetonitrile until no imidacloprid standard is detected.

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

[0045] Detection method:

[0046] S11, preparing a sample to be tested: 1 mL of urine was moved into a glass test tube, 0.3 mol / mL of an acetic acid buffer was added, 50 μL of a mixed internal standard solution of 100 mg / mL was added, and then incubation was performed in a 37°C water bath for 6 h;

[0047] S12, 0.5 mL of acetonitrile was vortexed uniformly, 3 mL of ethyl acetate was added, ultrasonic treatment was performed for 30 min, oscillation was performed for 30 min, and centrifugation was performed in a low-temperature centrifuge (4°C, 3400g) for 5 min, the supernatant was taken, and the above steps were repeated twice. The supernatant was combined, dried by blowing, redissolved with 200 μL of 50% methanol water, filtered through a 0.22 μL organic filter membrane, and a sample to be tested was obtained;

[0048] S13, 30 mg of the magnetic molecularly imprinted material was taken in a centrifuge tube, 3 mL of methanol was added to vortex and remove the supernatant, and then the sample to be tested in step S12 was added, oscillated for 2 min, and then the magnetic molecularly imprinted material and the solution were separated by a magnet, the solution was discarded, and methanol was added to wash the surface twice. Finally, 1 mL of acetonitrile was added as an eluent, the eluent was collected, and then dried by blowing with nitrogen, redissolved with chromatographically pure acetonitrile, filtered after ultrasonic treatment, and the concentration of imidacloprid was detected by high performance liquid chromatography

[0049] In step S11, the preparation method of the acetic acid buffer is as follows:

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

[0051] Comparative Example 2

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

[0053] S1, 1.2 g of FeCl3·6H2O, 0.1 g of PVP and 30 mL of deionized water were subjected to hydrothermal reaction at 200°C for 12 h, and after the reaction was completed, monodisperse Fe2O3 microspheres were obtained by centrifugation and washing;

[0054] S2, the Fe2O3 microspheres in step S1 were dispersed in 60 mL of anhydrous ethanol, 2 mL of tetraethyl orthosilicate and 4 mL of ammonia water were added and reacted for 12 h, then 1 mL of N-[3-(trimethoxysilyl)propyl]ethylenediamine and 1 mL of N-[3-(trimethoxysilyl)propyl]ethylenediamine were added as a silicon source and reacted for 12 h, and after the reaction was completed, SiO2-coated Fe2O3 microspheres were obtained by centrifugation, washing, and drying. Finally, the SiO2@Fe3O4 powder was obtained by calcining at 400°C for 3 h in 5% H2 and 95% N2. The SiO2-coated Fe3O4 microspheres, with a particle size of 154.5 nm, and a SiO2 shell thickness of 32.5 nm;

[0055] S3, 300 mg of phosphotriester standard was placed in a flask, 100 mL of acetonitrile, 12 mL of deionized water and 0.5 mL of methacrylic acid were added and stirred for 5 h, then 0.3 g of SiO2@Fe3O4 microspheres sol was added. Then 30 mmol of trimethylolpropane trimethacrylate and 60 mg of 2,2-azobis isobutyronitrile were added in turn and stirred for 20 h, then washed by centrifugation and repeatedly washed with acetonitrile until no phosphotriester standard was detected.

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

[0057] Detection method:

[0058] S11, prepare the sample to be tested: move 3 mL of urine into a glass test tube, add 0.4 mol / mL acetic acid buffer, then add 100 mg / mL of mixed internal standard solution 50 μL, and 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, ultrasonic for 35 min, oscillate for 35 min, and centrifuge in a low-temperature centrifuge (4°C, 3400g) for 6 min, take the supernatant, and repeat twice. Combine the supernatants, blow to dryness, redissolve with 200 μL of 50% methanol water, pass through a 0.22 μL organic filter membrane, and obtain the sample to be tested;

[0060] S13, take 40 mg of magnetic molecularly imprinted material in a centrifuge tube, add 4 mL of methanol to vortex and 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 off the solution, and then wash the surface with methanol 3 times. Finally, add 2 mL of acetonitrile as an eluent, collect the eluent, then blow dry with nitrogen, add chromatographically pure acetonitrile to dissolve, ultrasonic treatment, and filter, and then use high performance liquid chromatography to detect the concentration of phosphotriester.

[0061] The preparation method of the acetic acid buffer 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, and then add pure water to 55 mL, and finally add 70 μL of 85000 units / mL β-glucuronidase.

[0063] Comparative Example 3

[0064] The present comparative example provides a magnetic molecularly imprinted material for detecting a plurality of pollutants and a preparation method thereof, specifically comprising the following steps:

[0065] S1, 0.8 g of FeCl3·6H2O, 0.05 g of PVP and 20 mL of deionized water are subjected to hydrothermal reaction at 260℃ for 10 h, and after the reaction is completed, monodisperse Fe2O3 microspheres are obtained by centrifugation and washing;

[0066] S2, the Fe2O3 microspheres in step S1 are dispersed in 40 mL of anhydrous ethanol, 1 mL of tetraethyl orthosilicate and 3 mL of ammonia water are added and reacted for 8 h, then 0.7 mL and 0.5 mL of N-[3-(trimethoxysilyl)propyl]ethylenediamine are added as a silicon source and reacted for 8 h, and after the reaction is completed, SiO2-coated Fe2O3 microspheres are obtained by centrifugation, washing and drying. Finally, the SiO2@Fe3O4 powder is obtained by calcining at 350℃ for 2.5 h in 4% H2 and 96% N2. Among them, the SiO2-coated Fe3O4 microspheres, the particle size of Fe3O4 is 122.5 nm, and the thickness of the SiO2 shell is 24.3 nm;

[0067] S3, 200 mg of bisphenol A standard is placed in a flask, 60 mL of acetonitrile, 8 mL of deionized water and 0.3 mL of methacrylic acid are added and stirred for 4 h, then 0.2 g of SiO2@Fe3O4 microsphere sol is added. Then 15 mmol of trimethylolpropane trimethylacrylate and 40 mg of 2,2-azobis isobutyronitrile are added in turn and stirred for 18 h, then washed by centrifugation and repeatedly washed with acetonitrile until no bisphenol A standard is detected.

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

[0069] Detection method:

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

[0071] S12, 1.0 mL of acetonitrile was vortexed uniformly, 5 mL of ethyl acetate was added, ultrasonic was performed for 40 min, oscillation was performed for 40 min, centrifugation was performed in a low-temperature centrifuge (4℃, 3400g) for 8 min, the supernatant was taken, and the above steps were repeated twice. The supernatants were combined, blown to dryness, re-dissolved with 200 μL of 50% methanol water, filtered through a 0.22 μL organic filter membrane, and a sample to be detected was obtained;

[0072] S13, 60 mg of the magnetic molecularly imprinted material was taken in a centrifuge tube, 6 mL of methanol was added to remove the supernatant by vortexing, then the sample to be detected in step S12 was added, oscillation was performed for 3 min, then the magnetic molecularly imprinted material and the solution were separated by a magnet, the solution was poured out, and methanol was added to wash the surface twice. Finally, 2 mL of acetonitrile was added as an eluent, the eluent was collected, then blown dry with nitrogen, re-dissolved with chromatographically pure acetonitrile, and after ultrasonic treatment and filtration, the concentration of bisphenol A was detected by high performance liquid chromatography.

[0073] In the formula, 4 g of ammonium acetate was taken, 30 mL of pure water was added, 5 mL of glacial acetic acid was added, the volume was made up to 60 mL with pure water, and finally 80 μL of 85000 units / mL β-glucuronidase was added.

[0074] Example 1

[0075] The embodiment provides a magnetic molecularly imprinted material and a detection method for detecting a plurality of pollutants, and specifically comprises the following steps:

[0076] S1, 0.4 g of FeCl3·6H2O and 15 mL of deionized water were subjected to hydrothermal reaction at 120℃ for 8 h, and after the reaction was completed, single-dispersed Fe2O3 microspheres were obtained by centrifugation and washing;

[0077] S2, the Fe2O3 microspheres in step S1 were dispersed in 30 mL of anhydrous ethanol, 0.6 mL of tetraethyl orthosilicate and 2 mL of ammonia water were added and reacted for 5 h, then 0.5 mL and 0.2 mL of N-[3-(trimethoxysilyl)propyl]ethylenediamine were added as a silicon source and reacted for 5 h, and after the reaction was completed, SiO2-coated Fe2O3 microspheres were obtained by centrifugation, washing and drying. Finally, the SiO2@Fe3O4 powder was obtained by calcining at 300℃ for 2 h in 3% H2 and 97% N2. The SiO2-coated Fe3O4 microspheres, the particle size of Fe3O4 was 79.3 nm, and the thickness of the SiO2 shell was 11.2 nm;

[0078] S3, 0.2 g of SiO2@Fe3O4 powder obtained in step S1 was added to 5 mL of 0.2 wt% methanesulfonic acid aqueous solution, stirred at 80℃ for 4 h, then SiO2@Fe3O4 powder was obtained by centrifugation, and then added to 30 mL of anhydrous ethanol, then 0.3 mL of ammonia water and 0.1 mL of silane coupling agent KH-570 were added, and stirred at 30℃ for 5 h to obtain modified SiO2@Fe3O4 microsphere sol;

[0079] S4, 100 mg of imidacloprid standard was placed in a flask, 30 mL of acetonitrile, 4 mL of deionized water and 0.1 mL of methacrylic acid were added and stirred for 3 h, then 10 mL of modified SiO2@Fe3O4 microsphere sol in step S2 was added. Then 8 mmol of trimethylolpropane trimethacrylate and 20 mg of 2,2-azobis isobutyronitrile were added in turn and stirred for 16 h, then washed by centrifugation and repeatedly washed with acetonitrile until no imidacloprid standard was detected.

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

[0081] Detection method:

[0082] S11, prepare the sample to be tested: 1 mL of urine was moved into a glass test tube, 0.3 mol / mL of acetic acid buffer was added, then 100 mg / mL of mixed internal standard solution 50 μL was added, and then incubated in a 37℃ water bath for 6 h;

[0083] S12, 0.5 mL of acetonitrile was vortexed uniformly, 3 mL of ethyl acetate was added, ultrasonic was performed for 30 min, oscillation was performed for 30 min, and low-temperature centrifugation (4℃, 3400g) was performed for 5 min, the supernatant was taken, and the operation was repeated twice. The supernatant was combined, blown to dryness, re-dissolved with 200 μL of 50% methanol water, passed through a 0.22 μL organic filter membrane, and the sample to be tested was obtained;

[0084] S13, 30 mg of magnetic molecularly imprinted material was taken in a centrifuge tube, 3 mL of methanol was added to vortex and remove the supernatant, then the sample to be tested in step S12 was added, shaken for 2 min, then the magnetic molecularly imprinted material and the solution were separated by a magnet, the solution was poured out, and methanol was added to wash the surface twice. Finally, 1 mL of acetonitrile was added as an eluent, the eluent was collected, then blown dry with nitrogen, dissolved in chromatographically pure acetonitrile, treated by ultrasonic, filtered, and then the concentration of imidacloprid was detected by high performance liquid chromatography

[0085] In step S11, the preparation method of the acetic acid buffer is as follows:

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

[0087] Example 2

[0088] The present embodiment provides a magnetic molecularly imprinted material and a detection method for detecting a plurality of pollutants, which specifically comprises the following steps:

[0089] S1, 1.2g FeCl3·6H2O, 0.1g PVP and 30mL of deionized water were subjected to hydrothermal reaction at 200℃ for 12h, and after the reaction was completed, monodisperse Fe2O3 microspheres were obtained by centrifugation and washing;

[0090] S2, the Fe2O3 microspheres in step S1 were dispersed in 60mL of anhydrous ethanol, 2mL of tetraethyl orthosilicate and 4mL of ammonia were added and reacted for 12h, then 1mL of N-[3-(trimethoxysilyl)propyl]ethylenediamine was added as a silicon source and reacted for 12h, and after the reaction was completed, SiO2-coated Fe2O3 microspheres were obtained by centrifugation, washing and drying. Finally, the SiO2@Fe3O4 powder was obtained by calcining at 400℃ for 3h in 5% H2 and 95% N2. The SiO2-coated Fe3O4 microspheres, the particle size of Fe3O4 was 154.5nm, and the thickness of the SiO2 shell was 32.5nm;

[0091] S3, 1g of SiO2@Fe3O4 powder obtained in step S1 was added to 15mL of 1wt% methanesulfonic acid aqueous solution, stirred at 120℃ for 4h, and then SiO2@Fe3O4 powder was obtained by centrifugation, and then it was added to 100mL of anhydrous ethanol, then 2mL of ammonia and 1mL of silane coupling agent KH-570 were added and stirred at 55℃ for 10h to obtain modified SiO2@Fe3O4 microspheres sol;

[0092] S4, 300mg of triphenyl phosphate standard was placed in a flask, 100mL of acetonitrile, 12mL of deionized water and 0.5mL of methacrylic acid were added and stirred for 5h, then 50mL of modified SiO2@Fe3O4 microspheres sol in step S2 was added. Then 30mmol of trimethylolpropane trimethylacrylate and 60mg of 2,2-azobis isobutyronitrile were added in turn and stirred for 20h, then washed by centrifugation and repeatedly washed with acetonitrile until no triphenyl phosphate standard was detected.

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

[0094] Detection method:

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

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

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

[0098] In step S11, the preparation method of the acetic acid buffer is as follows:

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

[0100] Example 3

[0101] The embodiment provides a magnetic molecularly imprinted material and a detection method for detecting a plurality of pollutants, and specifically comprises the following steps:

[0102] S1, 0.8g of FeCl3·6H2O, 0.05g of PVP and 20mL of deionized water are subjected to hydrothermal reaction at 260℃ for 10h, and then single-dispersed Fe2O3 microspheres are obtained by centrifugation and washing after the reaction is completed;

[0103] S2, the Fe2O3 microspheres in step S1 were dispersed in 40 mL of anhydrous ethanol, 1 mL of tetraethyl orthosilicate and 3 mL of ammonia were added and reacted for 8 h, then 0.7 mL and 0.5 mL of N-[3-(trimethoxysilyl)propyl]ethylenediamine were added as a silicon source and reacted for 8 h, and after the reaction was completed, SiO2-coated Fe2O3 microspheres were obtained by centrifugation, washing, and drying. Finally, the SiO2@Fe3O4 powder was obtained by calcining at 350℃ for 2.5 h in 4% H2 and 96% N2. Among them, the SiO2-coated Fe3O4 microspheres, the particle size of Fe3O4 was 122.5 nm, and the thickness of the SiO2 shell was 24.3 nm;

[0104] S2, 0.5 g of the SiO2@Fe3O4 powder obtained in step S1 was added to 10 mL of a 0.5wt% methanesulfonic acid aqueous solution, stirred at 100℃ for 4 h, then centrifuged to obtain SiO2@Fe3O4 powder, which was then added to 60 mL of anhydrous ethanol, then 1 mL of ammonia and 0.5 mL of silane coupling agent KH-570 were added and stirred at 40℃ for 6 h to obtain modified SiO2@Fe3O4 microspheres sol;

[0105] S3, 200 mg of bisphenol A standard was placed in a flask, 60 mL of acetonitrile, 8 mL of deionized water and 0.3 mL of methacrylic acid were added and stirred for 4 h, then 30 mL of modified SiO2@Fe3O4 microspheres sol in step S2 was added. Then 15 mmol of trimethylolpropane trimethacrylate and 40 mg of 2,2-azobis isobutyronitrile were added in turn and stirred for 18 h, then washed by centrifugation and repeatedly washed with acetonitrile until no bisphenol A standard was detected. The prepared product was used as a standard sample.

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

[0107] Detection method:

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

[0109] S12, 1.0 mL of acetonitrile was vortexed uniformly, 5 mL of ethyl acetate was added, ultrasonic was performed for 40 min, oscillation was performed for 40 min, and centrifugation was performed in a low-temperature centrifuge (4℃, 3400g) for 8 min. The supernatant was taken and repeated twice. The supernatant was combined, blown to dryness, redissolved with 200 μL of 50% methanol water, passed through a 0.22 μL organic filter membrane, and the sample to be tested was obtained;

[0110] S13, take 60 mg magnetic molecularly imprinted material in a centrifuge tube, add 6 mL of methanol 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 off the solution, and then add methanol to wash the surface twice. Finally, add 2 mL of acetonitrile as an eluent, collect the eluent, then dry it with nitrogen, add chromatographically pure acetonitrile to dissolve, ultrasonically treat, filter, and then use high performance liquid chromatography to detect the concentration of bisphenol A.

[0111] wherein 4 g of ammonium acetate is taken, 30 mL of pure water is added, 5 mL of glacial acetic acid is added, and then the pure water is added to 60 mL, and finally 80 μL of 85000 units / mL β-glucuronidase is added.

[0112] Figure 1 is a flowchart of the preparation of the magnetic molecularly imprinted material for detecting pollutants and the detection method thereof.

[0113] Figure 2 (a) is a transmission electron microscope photo of the SiO2@Fe3O4 microspheres synthesized in Example 1, and it can be seen that the SiO2 wraps the Fe3O4 microspheres. Figure 2 (b) is a Gaussian fitting curve for counting the size of the Fe3O4 microspheres, and the particle size of the Fe3O4 microspheres is calculated to be 79.3 nm. The thickness of the SiO2 shell is about 11.2 nm 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 target substances.

[0114] 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. Both materials are paramagnetic, and the better dispersed example has stronger magnetism.

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

[0116] Figure 5 is a recovery rate curve of phosphorus acid triphenyl ester for Comparative Example 2 and Comparative Example 2 under different elution volumes. It can be seen that Example 2 only needs less eluent to maximize the recovery of phosphorus acid triphenyl ester. This is because the better dispersed magnetic molecularly imprinted material has a larger contact area, and only needs less eluent to make the target substance fall off from the magnetic molecularly imprinted material.

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

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

[0119] Those skilled in the art should understand that the above description is only several specific embodiments of the present application, not all embodiments. It should be noted that many modifications and improvements can also be made by those of ordinary skill in the art, and all modifications and improvements that do not exceed the scope of the claims should be considered as the protection scope of the present application.

Claims

1. A method for preparing a magnetic molecularly imprinted material for detecting a plurality of pollutants, characterized in that, Comprising the following steps: S1, 0.4~1.2 g FeCl3·6H2O, 0~0.1 g PVP and 15~30 mL of deionized water are subjected to hydrothermal reaction at 120~200 ℃ for 8~12 h, and after the reaction is completed, monodisperse Fe2O3 microspheres are obtained by centrifugation and washing; S2, the Fe2O3 microspheres in step S1 are dispersed in 30~60 mL of anhydrous ethanol, 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-(trihydroxysilyl)propyl]ethylenediamine are added as a silicon source, and reacted for 5~12 h, and after the reaction is completed, SiO2-coated Fe2O3 microspheres are obtained by centrifugation, washing and drying, and finally calcined at 300~400 ℃ for 2~3 h in 3~5% H2 and 97~95% N2 to obtain SiO2@Fe3O4 powder; S3, 0.2~1 g of SiO2@Fe3O4 powder obtained in step S2 is added to 5~15 mL of a 0.2~1 wt% methanesulfonic acid aqueous solution, stirred at 80~120 ℃ for 4 h, and then SiO2@Fe3O4 powder is obtained by centrifugation, and then added to 30~100 mL of anhydrous ethanol, then 0.3~2 mL of ammonia water and 0.1~1 mL of silane coupling agent KH-570 are added, and stirred at 30~55 ℃ for 5~10 h to obtain modified SiO2@Fe3O4 microspheres sol; S4, 100~300 mg of a contaminant standard is placed in a flask, 30~100 mL of acetonitrile, 4~12 mL of deionized water and 0.1~0.5 mL of methacrylic acid are added, stirred for 3~5 h, then 10~50 mL of modified SiO2@Fe3O4 microspheres sol in step S3 is added, then 8~30 mmol of trimethylolpropane trimethylacrylate and 20~60 mg of 2,2-azobis isobutyronitrile are added in turn, and stirred for 16~20 h, then washed by centrifugation and repeatedly washed with acetonitrile until no contaminant standard is detected, and then stored.

2. The method for preparing magnetic molecularly imprinted material for detecting various pollutants according to claim 1, wherein, The contaminant standard in step S3 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.

3. A method for detecting pollutants using the magnetic molecularly imprinted material prepared by the method of claim 1, characterized in that, Comprising the following steps: S11, prepare the sample to be tested: 1~5 mL of urine is moved into a glass test tube, 0.3~0.6 mol / mL of acetic acid buffer is added, 100 mg / mL of mixed internal standard solution 50 µL is added, and then incubated in a 37 ℃ water bath for 6~12 h; S12, 0.5-1.0 mL of acetonitrile was vortexed uniformly, 3-5 mL of ethyl acetate was added, ultrasonic was performed for 30-40 min, oscillation was performed for 30-40 min, low-temperature centrifuge was performed for 5-8 min, the supernatant was taken, the above steps were repeated twice, the supernatant was combined, and was blown to dryness, 200 µL of 50% methanol water was used for redissolution, 0.22 µL of an organic filter membrane was used for filtration, and a sample to be detected was obtained; S13, 30-60 mg of the magnetic molecularly imprinted material was taken in a centrifugal tube, 3-6 mL of methanol was added to remove the supernatant by vortexing, then the sample to be detected in step S12 was added, oscillation was performed for 2-3 min, then the magnetic molecularly imprinted material and the solution were separated by a magnet, the solution was poured out, methanol was added to wash the surface twice, finally, 1-2 mL of acetonitrile was added as an eluent, the eluent was collected, then was blown dry with nitrogen, was dissolved in chromatographically pure acetonitrile, was treated by ultrasonic, and was filtered, and the concentration of the pollutant was detected by using high performance liquid chromatography.

4. The method of detecting pollutants according to claim 3, wherein, The preparation method of the acetic acid buffer in step S11 is as follows: 3.85-4 g of ammonium acetate was taken, 25-30 mL of pure water was added, 3-5 mL of glacial acetic acid was added, the volume was made up to 50-60 mL with pure water, and finally 60-80 µL of 85000 units / mL β-glucuronidase was added.

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