Study On Detection Of Organophosphorus Pesticide Residues By Biomimetic Immunoassay Based On Fluorescence Labeling

In order to prevent organophosphorus pesticide residues from threatening human health,it is very important to establish a simple,rapid and accurate method for the detection of organophosphorus pesticide residues.Immunoassay is widely used in the detection of organophosphorus pesticide residues due to its high specificity,no expensive instruments and high cost effectiveness.However,it is difficult for the traditional immunoassay method to prepare antibodies,and the stability and accuracy of the determination results are relatively low.In this study,three new biomimetic immunoassay methods for the detection of organophosphorus pesticide residues were established.The main findings are as follows:1.Study on detection of trichlorfon residues in vegetables by combining biomimetic immunoassay based on quantum dot labeling with capillary electrophoresis.A molecularly imprinted polymer with selective recognition for trichlorfon was synthesized.Based on the molecularly imprinted polymer as the biomimetic antibody,a novel biomimetic immunoassay method with high sensitivity for the detection of trichlorfon residues was established.Under the optimal conditions,the limit of detection(LOD,IC₁₅)and sensitivity(IC₅₀)of this method was 0.35±0.021?g L^-1 and 0.81±0.025 mg L^-1,respectively.In order to evaluate the accuracy of the method,the recovery experiments of carrot and zucchini samples were carried out,and the recoveries were 80.1%-95.3%.After that,the method was used to determine the residues of trichlorfon in rape and leek samples,and there was no significant difference between the results obtained by this method and those obtained by gas chromatography.2.Study on biomimetic fluorescence immunoassay based on quantum dot labeling for the simultaneous determination of three organophosphorus pesticide residues in fruits.Based on 2-?diethoxyphosphoric acid?acetic acid as template molecule and Fe₃O₄@SiO₂as carrier,a superparamagnetic core-shell molecularly imprinted polymer with multiple recognition sites and high adsorption capacity was prepared.Based on this molecularly imprinted polymer as biomimetic antibody and quantum dot as label,a biomimetic fluorescence immunoassay was developed for the simultaneous determination of methyl parathion,chlorpyrifos and trichlorfon.Under the optimal conditions,the LOD of the method was 0.21±0.021?g L^-1,0.44±0.069?g L^-1,and 0.32±0.033?g L^-1 for methyl parathion,chlorpyrifos,and trichlorfon,respectively.In order to evaluate the accuracy of the method,apple and orange samples spiked with methyl parathion,chlorpyrifos,and trichlorfon were detected,and the recoveries ranged from 73.1%to 119.3%.Finally,this method was applied to detect three kinds of pesticides in pear,kiwifruit,and banana samples,and there was no significant difference between the results of this method and results of gas chromatography.3.Study on the determination of multiple organophosphorus pesticide residues in agricultural products based on magnetic assisted fluorescence probe.Based on 6-carboxyfluorescein?6-FAM?labeling aptamer as the probe and functionalized magnetic nanoparticles as the separation carrier,a rapid and sensitive fluorescence assay for the determination of multiple organophosphorus pesticides was successfully developed.The conditions affecting the competitive binding reaction were optimized.Under the optimal conditions,the LOD for trichlorfon,glyphosate,and malathion was 72.20 ng L^-1,88.80 ng L^-1,and 195.37 ng L^-1,respectively.Additionally,the method was applied for the detection of trichlorfon,glyphosate,and malathion spiked in lettuce and carrot samples.The recoveries were in the range of 79.4%-118.6%,and the relative standard deviations?RSDs?were less than 4.9%.The method has high sensitivity and low limit of detection,so it can provide a new method for the determination of organophosphorus pesticides.