Study Electrochemical Sensors For The Detection Of Organophosphorus Pesticides

People pay more attention to Food Safety,especially the security problems caused by pesticides which are absolutely necessary for agricultural production.Organophosphorus pesticides were widely used pesticides and the largest amount of pesticide production.Vegetables are delivered to vegetable market which often sprayed with organophosphorus pesticides and had not been fully degraded,then the vegetables are processed into food that harm on human body.Meteorological chromatographic and other traditional detection technologies were hardly to satisfy the increasing requirements of the detection,electochemical biosensors provided a promising way to detection of organophosphorus pesticide.In the paper,graphite and iron phosphide were prepared to composite electrodes by thick-film technology.The conditions of the making an composite electrodes was studied,such as cellulose acetate,graphite and phosphorus iron,were discussed.The electrode had good the resistivity of the electrode and electrocatalytic activity of composite electrode.chemical stability?reproducibility.In potassium ferrocyanide solution or hydroquinone solution,the activities of composite electrode were characterized by cyclic voltammetry,and the detection limits was 9.76×10-7mol/L.Disposable electrodes were made of graphite which blended with TCNQ and cellulose acetate binder,the nickel foam has good conductivity and plasticity,it played a huge part in conduction of electricity.Enzymatic electrode biosensors were prepared by immobilizing acetylcholinesterase with the cross-linking agent named glutaraldehyde.The conditions of the making an enzymatia electrode was discussed.And then different factors which had effects on enzymatic electrodes were investigated.Chitosan was used to immobilize enzymes and modified carrier electrodes with TCNQ,in order to have good working conditions for biosensor.Chitosan 3d structure and good biocompatibility greatly reducing the loss of enzyme activity,And then different factors which had effects on enzymatic electrodes were investigated.Using two kinds of cholinesterase electrode used for the detection of chlorpyrifos,the linear relationship between the percentage of inhibition and the logarithm of the concentration of chlorpyrifos were excellent.Using glutaraldehyde crosslinking method and chitosan embedding method of cholinesterase electrode for organophosphorus pesticide detection limits were respectively 5.67x10-11mol/L and 6.95x10-11mol/L.