Preparation And Application Of Carbaryl Magnetic Molecularly Imprinted Polymers

Carbaryl?CBR?is an N-methylcarbamate that is widely used as a broad-spectrum,high efficiency insecticide,can be used for controlling rice planthopper,leafhopper,thrips and the like.Its mechanism of action is to inhibit the activity of acetylcholine esterase,affecting the normal operation of the nervous system,producing symptoms similar to organophosphate compound poisoning.Therefore,it is extremely necessary to detect CBR residues in food.Currently,the methods for detecting CBR residues in food are complicated in sample preparation techniques,and it is difficult to achieve the purpose of rapid detection.Therefore,it is urgent to establish a rapid,accurate and simple method for detecting trace amounts of CBR in food.Magnetic nanomolecular imprinting technology combines magnetic nanoparticles?MNPs?with molecular imprinting technology?MIT?to produce magnetic nano-molecularly imprinted polymers?MMIPs?which not only have the characteristics of"selective"adsorption of molecularly imprinted polymers?MIPs?,but also have the characteristics of"dynamic"separation of MNPs,achieving rapid separation and enrichment of the detected substances.Based on this technology,in this paper,the polymers with high selectivity and excellent stability to CBR were prepared,and they were applied in rapid separation and enrichment of trace CBR in complex matrices.The main conclusions of the study are listed as follows:?1?Fe₃O₄ magnetic nanoparticles?Fe₃O₄MNPs?with good monodispersity and high magnetization were prepared by chemical coprecipitation method and surface modified with silane coupling agent.IL@MMIPs were prepared by suspension polymerization,using CBR as a template molecule,methacrylic acid?MAA?as a functional monomer,functionalized ionic liquid 1-butyl 3-methylimidazole-6-fluorophosphate?IL?as an auxiliary medium,azobisisobutyronitrile?AIBN?as an initiator,and ethylene glycol dimethyl acrylate?EGDMA?as a crosslinking agent.By investigating the effect of the different preparation conditions,got the optimal preparation conditions were:CBR0.5 mmoL,MAA4 mmoL,EGDMA8 mmoL,IL3 mL,acetonitrile as solvent,and the volume was 100 mL.?2?Characterization experiments were carried out on the synthesized IL@MMIPs to investigate the morphology,structure,magnetic properties and crystal form of the polymer.The experimental results showed that the shape of the microspheres was regular with an average diameter of approximately 400 nm,the holistic surface structure was loose.The products obtained in each step contain characteristic peaks of Fe-O,showing polymerization process didn't transform the crystal structure of Fe₃O₄MNPs,and the Fe₃O₄MNPs were successfully encapsulated in the molecularly imprinted materials.The saturation magnetization of IL@MMIPs was 31.753 emu/g.?3?Through kinetic adsorption experiments,combined with the analysis of quasi-first-order and quasi-second-order kinetic models,and the results showed that the adsorption capacity of CBR on IL@MMIPs increases significantly from 0 to 40 min,and the adsorption tended to balance after 40 min.The kinetic model fitting showed that the adsorption of CBR on the IL@MMIPs conformed to the pseudo-second-order kinetic model;The thermodynamic adsorption experiments and the Scatchard model analysis showed that there were two binding sites in the IL@MMIPs,wherein the equilibrium dissociation constant of the high affinity sites was K_d=0.9242 mg/L,and the maximum apparent adsorption was Q_max=20.22 mg/g,low affinity sites K_d=4.645 mg/L Q_max=29.08 mg/g,no specific adsorption of non-imprinted polymers?IL@MNIPs?,K_d=42.05 mg/L Q_max=7.33 mg/g;Selective adsorption experiments showed The adsorption amount of IL@MMIPs for template molecule CBR and its structural analogs was much higher than that of IL@MNIPs,but for other reference compounds,the adsorption amount of the two was not much different;Finally,MMIPs were used as adsorbents for the detection of trace CBR in food,and compared with the conventional SPE column extraction results.The results showed that the extraction effect of MMIPs was better than that of SPE column.