Electrochemical Sensor Sensitized With Graphene And Hollow Gold Nanoparticles For Quantification Of Methyl Parathion And Parathion

Organophosphorus pesticides（OPs）play an important role in controlling plant diseases and insect pests.Considerable economic benefits have been created because of the use of pesticides in agriculture.However,with the increasing of the number and variety of pesticides,the adverse effects of pesticides on social development are increasingly apparent.On the one hand,when the pesticides are absorbed to the body through skin and respiratory tract,the people are inclined to show acute and chronic poisoning symptoms.And some studies have shown that pesticides may have potential teratogenic,carcinogenic and mutagenic effects.On the other hand,the presence of pesticide residues in atmosphere,water,soil has caused serious environmental pollution problems.As awareness of environmental protection and public security has increased,rapid and efficient analysis techniques for the detection of pesticide residues have attracted attentions.In this work,an electrochemical sensor based on graphene and hollow gold nanoparticles（HAuNPs）was constructed for the rapid detection of methyl parathion and parathion.The performances of the sensor including selectivity,stability,fabrication reproducibility and repeatability were evaluated.The practicality of the electrochemical sensor for fruit and vegetable samples were also analyzed.The main results were shown as follows:（1）Graphite oxide was prepared referring to the modified Hummers methods,and exfoliated via ultrasonic treatment to obtain graphene oxide（GO）dispersion.According to one-step electrodeposition method,the GO was coated on the surface of the electrode and concurrently reduced to graphene（rGO）.HAuNPs were synthesized by chemical reduction method and a drop-coating method was used to form a sensing film on the surface of the electrode.Therefore,the electrochemical sensor based on graphene and hollow gold nanoparticles（HAuNPs）was developed.（2）Methyl parathion and parathion were selected as model targets,and the electrochemical behaviors of them on sensor were evaluated using cyclic voltammetry（CV）and square wave voltammetry（SWV）measurements.Meanwhile,to achieve better sensitivity for the presented sensor,various experimental parameters were optimized in detail,such as concentrations of GO,amount of HAuNPs,pH,accumulation potential and accumulation time.Under optimal conditions,this sensor offered good linear current responses to methyl parathion concentrations in the range from 3.0×10^-77 to 1.0×10^-55 mol L^-11 and parathion concentrations from 1.0×10^-77 to 5.0×10^-55 mol L^-1.The limit of detection（signal to noise,S/N=3）was1.18×10^-77 mol L^-11 for methyl parathion and 2.32×10^-88 mol L^-11 for parathion.What’s more,this sensor was applied to the determination of methyl parathion in spiked fruit samples with satisfactory recoveries ranging from 76.7%to 106.0%,as well as parathion in spiked vegetable samples with recoveries ranging from 81.7%to 112.1%.