| New neonicotinoid insecticides that possess broad spectrum, high efficiency, low toxicity, low residue and it is safe for human, animals, plants and natural enemies, and have a contact poisoning, stomach poisoning and systemic effect for pests, are widely used to prevent pests in rice, vegetables, fruits and other crops. Among them, the quantity of clothianidin, inidacloprid, imidaclothiz and thiacloprid were larger in controlling pests. Their residues are easy leaching into groundwater and river water in the field with the rainwater. They are "very highly toxic" to bees and aquatic invertebrates. Although new neonicotinoid is lower in toxicity toward mammals, it poses a threat to human if it is present in excessive amounts in foods. So it is necessary for the real-time monitoring their residues in agriculture crops and environment. In this research, the clothianidin and thiacloprid molecularly imprinted polymers were synthesized and characterized.In this study, A molecularly imprinted polymer for the selective solid phase extraction of clothianidin was prepared using clothianidin as a template, methacrylic acid and styrene as functional monomers, ethylene glycol dimethacrylate as a cross-linker, acetonitrile as a porogen and 2,2-azobisisobutyronitrile as an initiator. The structure of polymer were characterized using scanning electron microscopy and fourier transform infrared spectroscopy. Dynamic adsorption tests and selective adsorption tests indicated that the molecularly imprinted polymers exhibited good recognition ability and fast adsorption-desorption dynamics toward clothianidin. Scathcard analysis showed that the maximum adsorption of MIP for clothianidin is 48.26 mg/g. Using this imprinted polymer as a sorbent, a new method of molecularly imprinted solid phase extraction coupled to high performance liquid chromatography for the determination of clothianidin residues was developed. The molecularly imprinted solid phase extraction procedure was optimized to clean up and enrich clothianidin residue in tap water, river water, paddy water, soil, tomato, grape The average recoveries of clothianidin spiked at 0.005 to 0.05 mg/L were 84.32% to 97.68% in water samples with a relative standard deviation 1.46% to 4.79%(n=3) The average recoveries of clothianidin spiked at 0.01 to 0.1 mg/kg were 87.19% to 96.74% in soil, rice, grape and tomato, with a relative standard deviation 1.78% to 6.02%(n=3) Overall, this study provides a sensitive and effective method for the accurate determination of clothianidin residues in environment samples.A molecularly imprinted polymers was synthesized with thiacloprid as template, methacrylic acid and styrene as functional monomer, and ethylene glycol dimethyl acrylate as the cross-linker, azodiisobutyronitrile as initiator, acetonitrile as the pore, and the polymerization took place in a water bath at 55℃ for 24h. The proper ratio of the functional monomers to the template in polymerization was selected as 1:4:6 in which the best specific affinity Static adsorption and dynamic adsorption test showed that the synthesis of thiacloprid molecularly imprinted polymer can rapidly absorb, and have good selectivity and specificity for imidacloprid, imidaclothiz, thiacloprid. Scatchard analysis showed that the maximum adsorption capacity of the molecularly imprinted polymers were 31.67 mg/L, 36.73 mg/L,45.33 mg/L. As solid phase extraction adsorbents, the optimized extraction conditions were 5mL methanol activated the cartridge followed by 5mL water,10 ml of 20% methanol washing,5 mL 5% acetic acid methanol to elute the targets. Under optimized conditions, the paddy water, soil, brown rice, tomato and grape spiked with three concentration, were separated and enriched by the MIP-SPE The recoveries of imidacloprid, imidaclothiz, thiacloprid were 80.21～96.36%,81.28～97.53% and 83.42～98.78%, with RSD 1.24%～3.78%,2.36%～4.52%, and 1.42%～3.97%(n=3), the results was satisfied. |
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