Study On Detection Of Organophosphorus Pesticides Based On Molecularly Imprinted Electrochemical Sensors

Organic phosphorus pesticide is a kind of broad spectrum and efficient contain organic phosphate insecticide, including methyl parathion(MP), which is a highly toxic organophosphate insecticides. The residues of MP in the human body would cause various diseases damaging to human health throughout the food chain. The traditional method of electrochemical instrumentation conditions require a highly pre-treatment operation, relatively complicated process and could not be recognized selectively from complex matrices methyl parathion. To overcome these problems, the Graphene/Au NPs nanoparticles composites, which combined the advantages of electrochemical sensors and molecular imprinting technique, synthesized as the electrocatalysis conductive material to modified on the electrode. The molecularly imprinted polymer was modified on the electrode surface as a sensitive membrane element to detect methyl parathion for a high sensitivity and selectivity detection.First of all, the Graphene/Au NPs composites were prepared using the Na BH4 reduction method. The MIPs were prepared with Zn MOTPP and MAA respectively as function monomer using suspension polymerization method. The MIPs and Graphene/Au NPs composites were characterized by scanning electron microscopy and infrared spectroscopy.Secondly, for the preparation of Graphene/Au NPs/GCE electrochemical sensor, the Graphene/Au NPs composites were dropped on the GCE and dried in vacuum. Subsequently, the MIPMs-MAA and MIPMs-Zn were also coated on the surface of above GCE and dried in vacuum. The MIPMs-MAA/Graphene/Au NPs/GCE and MIPMs-Zn/GCE electrochemical sensors were obtained.Finally, cyclic voltammetry(CV) and different pules voltammetry(DPV) were used to investigate the response of the electrochemical redox reaction of between the sensors and MP. The results showed a highly electrocatalytic activity and st ronger adsorption toward MP. The single-factor variables including adsorption tim e, p H value, amount of composites modified electrodes, selective of different pes ticides and anti-interference were considered via DPV. Compared with different r esponse of the electrochemical sensors in MP solutions, MIPMs-Zn molecularly i mprinted electrochemical sensor exhibited a shortest adsorption time, widest linear range and lowest detection limit. The MIPs were washed in solution to removethe MP and the surface of MIPMs-Zn was left efficiency of molecularly recogn ition cavities. The MIPMs-Zn was prepared by using MP as the temple and porp hyrins as the monomer. Due to the coordination between the metal porphyrins an d MP, the imprinting cavity sites of MIPMs-Zn were increased. Finally, the sele ctive adsorption experiment was also studied in this paper. The results showed th at the MIPMs-Zn and MIPMs-MAA electrochemical sensors exhibited a higher a dsorption capacity toward MP than the other similar structure to pesticides. Com pared with the Graphene/Au NPs/GCE and the MIPMs-MAA/Graphene/Au NPs/GC E, the MIPMs-Zn/Graphene/Au NPs/GCE showed higher sensitivity; higher selectiv ity and shorter response time, which can be quickly respond to the content of m ethyl parathion, the MIPMs-Zn/Graphene/ Au NPs/GCE was proved to be a kind of extremely potential application value of detection method.