Moleculary Imprinted Polymer Microspheres For Solid-phase Extraction Of Organophosphorus Pesticide Residues In Milk

In this dissertation, we explore a new sample pre-treatment: the molecularly imprinted-solid phase extraction, to extract organophosphorus pesticide residues from biological sample that contain complex matrix, such as milk. In this paper, The molecularly imprinted polymeric microspheres (MIPs) was prepared by suspension polymerization, and its recognition property was characterized by static adsorption model. In the end, the MIPs was used to packing material of solid phase extraction to extract methamidophos residues from milk. Specific researchful content of this thesis as followed:(1) In order to predict the interaction between imprinted moleculary and functional monomer, Use B3LYP methods with 6-31+G(d, p) basis set to calculate, and use the AIM theory at 6-31+G(d, p) basis set to analysis charge density (ρc) and laplacian value (?2ρc) of stable system. in the result, ?2ρc>0 that was in the typical hydrogen bond range. It was obvious that the selected functional monomer was correct, and functional monomer with imprinted molecularly can form stable complex with multi-bind sets by hydrogen bond. The result also can help us research the recognition principle and mechanism.(2) The molecularly imprinted polymeric microspheres was prepared by suspension polymerization, using methamidophos (or acephate) as printing molecule,α-MAA as functional monomer and trimethylolpropane triacrylate (TMPTA) as cross-linker. The effect of the ratio of printing molecule to monomer to cross-linker on MIPs adsorption capacity, and influence of organic solvent on size distribution of the MIPs was investigated. The recognition property of the MIPs was evaluated using Langmuir model. The data obtained in equilibrium adsorption experiment was processed by Scatchard analysis, which displayed that the MIPs had two different affinity binding sets. When acephate (or methamiodophos) and isocarbophos were used as competitive molecules, the values of resolution factorαwere lager than 1.0, which exhibited MIPs had a good recognition characteristic.(3) Methamiodophos MIPs was applied for solid phase extraction (SPE) of methamidophos in milk. In the optimum conditions, methamidophos solution was extracted by MISPE (molecular imprinted polymer as stationary phase), the recovery of 96% revealed MISPE could be applied for cleaning sample and enriching the template in the complicated samples, but it was not the case with non-imprinted polymer. The milk sample was spiked with the lever of 100μg/kg of methamidophos, acephate and isocarbophos, the average recovery were 87.4%, 12.7% and 3.4%, respectively. It was found that MISPE has special affinity to methamidophos and its recovery could meet the requirement of pesticide residues detection. In the same condition, C18 cartridge was also used for pretreatment of the spiked milk sample. Comparison with C18, the MIPs had advantage for clean-up samples, especially excellent selectivity.