The Synthesis And Performance Of Separation And Enrichment Of Magnetic Dummy Template Molecularly Imprinted Polymers For Organophosphorus Pesticides

Organophosphorus pesticides?OPPs?are commonly used as pesticides in agriculture,most of which show high acute toxicity.And they are suspected to be mutagens,carcinogens,endocrine disruptors and important environmental pollution.In recent years,the threat of pesticide residues in the environment to humans and wildlife has increased dramatically.Therefore,to prevent these uncontrollable influences on human health and environmental pollution,and at the same time,to provide a good ecological environment and safe products,the development of efficient organophosphorus pesticide adsorbent is pretty essential.However,the concentration of the residual organophosphorus pesticides in the environment is extremely low,and the samples to be measured need to be separated and enriched before the measurement.Therefore,it is necessary to develop separation and enrichment materials with high adsorption rate,high adsorption capacity,good selectivity and high reuse efficiency.For this purpose,the preparation,characterization,separation and enrichment of magnetic dummy template molecular imprinted polymers for organophosphorus pesticides were studied on the basis of literature review.The magnetic dummy template molecularly imprinted polymer of organophosphorus pesticides was synthesized and used as a new material for magnetic solid phase extraction in the separation and enrichment of trace organophosphorus pesticide residues in practical samples.A new method for the determination of trace organophosphorus pesticides in wine by magnetic dummy template molecular imprinting-magnetic solid phase extraction-high performance liquid chromatography was established.The specific findings are as follows:The surface imprinted polymer of magnetic dummy template was synthesized directly on the surface of the magnetic Fe₃O₄ nanoparticles by using diethyl?4-methylbenzyl?phosphonate as the dummy template molecule.The structure and morphology of the materials were characterized by X-ray diffraction?XRD?,vibrating sample magnetometer?VSM?,scanning electron microscopy?SEM?,transmission electron microscopy?TEM?and Fourier transform infrared spectroscopy?FT-IR?.At the same time,the preparation conditions of the polymer materials were optimized,including the amount of catalyst?ammonia?,the ratio of solvent?methanol and water?and mechanical stirring time.Under the optimal experimental conditions,the obtained polymer materials have uniform morphology and size and good dispersion.Moreover,the dummy template technology is used to synthesize the surface molecularly imprinted polymer,which avoids the measurement error caused by the leakage of template molecule in quantitative analysis,and improves the accuracy of the analysis results.A simple and effective sol-gel method combined with surface molecular imprinting technique were used to synthesize the magnetic dummy template surface molecularly imprinted polymer of organophosphorus pesticides?Fe₃O₄@DMMIPs?directly.We used Fe₃O₄ with excellent magnetic properties as the carrier,ethyl paraoxon as the dummy template molecule,3-aminopropyltriethoxysilane as the functional monomer and tetraethylorthosilane?TEOS?as a crosslinking agent,to synthesize the DMMIP polymerization layer.The selective separation and enrichment of methyl parathion and phoxim were realized.Meanwhile,the structure and morphology of Fe₃O₄@DMMIPs were characterized and analyzed by scanning electron microscopy?SEM?,transmission electron microscopy?TEM?,Fourier transform infrared spectroscopy?FT-IR?,and vibrating sample magnetometer?VSM?.Moreover,the effects of the composition of solvent?methanol and water?,the ratio of crosslinking agent to functional monomer and the prepolymerization time on the morphology of the synthesized polymer were investigated.Under the optimal experimental conditions,the adsorption performance,selectivity and recycling performance of the polymer materials were explored.The results showed that Fe₃O₄@DMMIPs had a good selective adsorption capacity for methyl parathion and phoxim.It can not only reach the kinetic adsorption equilibrium for 15 minutes,but also have a high equilibrium adsorption capacity of 195.7 mg g-1.Further more,it has good recycling and affinity.The method was efficient and simple,which avoided the tedious modification process of functional groups on the nuclear surface and simplified the synthesis steps of the traditional method and greatly reduced the polymerization reaction time.The organophosphorus pesticide magnetic dummy template molecularly imprinted polymer materials were used as magnetic solid-phase extraction?MSPE?adsorbent for the enrichment and separation of practical samples.And the conditions of magnetic solid-phase extraction were optimized,mainly including the type of eluent.elution time and the pH value of solution.In addition,Fe₃O₄@DMMIPs-MSPE-HPLC method was established for the separation,enrichment and determination of organophosphorus pesticide residues in practical samples.The results showed that the method had a good linear range.And the recoveries of methyl parathion and phoxim were between 90.8 and 92.9%with relative standard deviations of 4.7%and 5.1%,respectively.The limit of detection was 0.56 ng mL-1 and 0.08 ng mL-1.