| Pesticides are widely used as one of the important means to control pests and kill weeds,but they have always been a focus of concern because of their difficulty in degradation,long residual period and the harm to the environment and crops.Therefore,it is necessary to conduct in-depth research on pesticide residues,and to establish an effective analysis and detection method for pesticide residues.Magnetic dispersed solid phase extraction（MDSPE）has many excellent characteristics in the field of sample pretreatment.In this thesis,combined with the magnetic characteristics of magnetic nano-materials,MDSPE combined with spectroscopy/chromatography were applied to the extraction and detection of pesticide residues（bipyridine herbicide,thiazole pesticide,sulfonylurea pesticide and pyrethroid pesticide）in actual complex matrix.1.Magneticα-Zr P/Fe3O4 nanocomposites were prepared by Mechanical-chemical method and used as an extractant for MDSPE in combination with high performance liquid chromatography（HPLC-UV）for the separation and analysis of the bipyridyl herbicides diquat and paraquat.Under the optimal experimental conditions,the concentrations of both showed a good linear relationship with the liquid chromatographic peak areas in the range of 5.0×10-3-1.5μg/m L with the correlation coefficients between 0.9995 and 0.9998.The detection limits of DQ and PQ were 1.2μg/L and 2.0μg/L,and the limits of quantification were 4.0μg/L and 6.6μg/L,respectively.The method was applied to the determination of DQ and PQ in vegetable samples（Chinese cabbage and lettuce）with the spiked recoveries of 81.3%-101.5%and the relative standard deviations（RSDs）of 3.1%-6.1%.2.The novel CB[8]/α-Zr P/Fe3O4 composites were prepared by chemical co-precipitation and used as an extractant for MDSPE in combination with HPLC-UV to study the determination of tricyclazole in cereals（rice,brown rice and oats）.The factors affecting the extraction efficiency were investigated.Under the optimal conditions,a good linear relationship between the concentration and peak area of tricyclazole was observed in the linear range of 2.5×10-3-0.5μg/m L with a linear correlation coefficient of 0.9995,the limit of detection of 1.1μg/L and the limit of quantification of 3.8μg/L.The method was applied to the determination of tricyclazole in three cereals,rice,brown rice and oats,with the spiked recoveries of 76.9%-101.1%and RSDs of 4.1%-8.5%.3.Fe3O4/Mo S2 composite was prepared by combining Fe3O4 with molybdenum disulfide（Mo S2）by mechanochemical method and used as MDSPE extractant in combination with HPLC-UV for the determination of metsulfuron,a sulfonylurea pesticide,in cereals and river water,while the factors affecting the extraction efficiency of metsulfuron were optimized for the conditions.Under the optimal experimental conditions,metsulfuron showed good linearity between concentration and peak area in the range of 2.5×10-3-12.5×10-2μg/m L with a correlation coefficient of 0.9996.The limits of detection and limits of quantification of the method were 2.0μg/L and 6.9μg/L,respectively.This proposed method was applied to river water and wheat samples with spiked recoveries of 81.1%-97.3%and relative standard deviation（RSD）less than5.3%.4.Magneticβ-CDP/Fe3O4/Mo S2 composites were prepared by assembling Fe3O4 andβ-cyclodextrin（β-CD）nanoparticles on layered Mo S2,and a method was developed for the determination of pyrethroid pesticides（bifenthrin）in fruits（apple and hawthorn）by MDSPE coupled with HPLC-UV.The main factors affecting the extraction efficiency of bifenthrin were also experimentally investigated and optimized.Under the optimal conditions,the linearity of bifenthrin was good in the range of 8.0×10-3-1.0μg/m L with a correlation coefficient of 0.9995.The detection limit of the method was 3.2μg/L and the quantification limit was 10.0μg/L.The spiked recovery experiments were performed on apple and hawthorn samples,and the recoveries were in the range of 75.7%-94.2%with RSDs of 2.4%-7.5%.In this thesis,there are 72 figures,22 tables and 183 references. |
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