Investigation On The Construction And Application Of Electrochemical Sensors For Fenitrothion

In response to the increasing contamination situation of pesticides and metabolites,it is urgent to establish a method for rapid and convenient detection of pesticides in water.Electrochemical sensors have proven to be a promising detection method due to their low detection limits,in-situ detection,fast response,miniaturization,low cost,simplicity of operation and high selectivity.In this paper,two electrochemical sensors were prepared for the detection and analysis of the organophosphorus pesticide fenitrothion（FT）and applied to environmental water samples with good results.The main studies in the paper include:（1）Hydrothermal preparation of magnesium-iron layered bimetallic hydroxide（Mg-Fe-LDH）,which was immobilized on the surface of glassy carbon electrode by perfluorosulfonic acid-based polymer（nafion）solution to prepare the working electrode of the electrochemical sensor.Mg-Fe-LDH was analyzed by scanning electron microscopy（SEM）,fourier transform infrared spectroscopy（FT-IR）,X-ray diffraction（XRD）and X-ray photoelectron spectroscopy（XPS）for characterization.Cyclic voltammetry（CV）,differential pulse voltammetry（DPV）and electrochemical impedance spectroscopy（EIS）for studying the electrochemical properties.The influencing factors of electrode preparation（loading of Mg-Fe-LDH）and fenitrothion analysis（enrichment potential and enrichment time,p H）as well as the effect of scan rate on the experimental results were investigated.Under the optimal conditions,the differential pulse voltammetry（DPV）response currents showed good linearity in the range of 2×10^-7mol·L^-1to 2×10^-5mol·L^-1and 2×10^-5mol·L^-1to 1×10^-4mol·L^-1with low detection limits(0.05μmol·L^-1)for the concentration of fenitrothion.The method was applied to the determination of fenitrothion in real samples,with a spike recovery of 99.34%-103.3%.（2）Molecularly imprinted polymers（MIP）were synthesized by sol-gel method using fenitrothion,3-aminopropyltriethoxysilane and tetraethyl orthosilicate as template molecules,functional monomers and cross-linking agents.The electrochemical sensor working electrode was prepared by immobilizing MIP on the surface of silver nanoparticle modified glassy carbon electrode by nafion solution.MIP was characterized by FT-IR and SEM.Electrochemical properties were investigated by EIS and CV.The results showed that the MIP electrode exhibited typical electrochemical differences and electrochemical sensor based on the prepared MIP electrode showed good performance for fenitrothion analysis.The factors influencing electrode preparation（loading of MIP,elution time）and fenitrothion analysis（incubation time）were investigated.Under the optimal conditions,the response current of DPV showed a good linear relationship with the concentration of fenitrothion in the range of 3.45×10^-11mol·L^-1-3.45×10^-7mol·L^-1with a very low detection limit(0.005 nmol·L^-1).The method was applied to the determination of fenitrothion in real samples,with a spike recovery of 95.8%-102%.Figure[23]Table[8]Senate[145]...