Electrochemical Sensing Of Hydrogen Peroxide And Carbendazim Residues In Agricultural Products

As a source of food,agricultural products directly affect the safety of food.The harmful substances in agricultural products directly affect the safety of agricultural products,such as hydrogen peroxide(H2O2)as an efficient,non-toxic,tasteless and environmentally friendly disinfectant,is widely used as a disinfectant and fungicide in the processing and manufacturing of various foods such as milk,juice,beer,and aseptic packaging for drinking water,aquatic products,fruits and vegetables.The residue caused by the excessive addition of H2O2 poses a serious threat to human health;as a widely used high-efficiency systemic fungicide,carbendazim(CBZ)has a good control effect on crop diseases and insect pests.But excessive use can also pose a threat to the ecological environment and human health.Therefore,the detection of H2O2 and CBZ residues is of great significance.However,the current conventional detection methods are expensive,complicated in operation,and cumbersome in the pretreatment process of the sample.For the reason of that,the development of new and efficient residue detection methods has become a research hotspot in recent years.In this thesis,H2O2 and CBZ were used as the detection objects,and electrochemical methods based on carbon-based nanomaterials were developed to develop low-cost,high-sensitivity,high-specificity and easy-to-use electrochemical sensors for the efficient detection of H2O2 and CBZ residues in agricultural products.The main work includes the following parts:1)Electrochemical reduction of graphene oxide(ERGO)-loaded Hemin-containing nanocomposite(H-ERGO)was prepared by a simple method,and a high-performance H2O2 biosensor was constructed,which exhibited a wide linear range,good stability and high selectivity for H2O2 detection,which mainly due to the high conductivity and large specific surface area of ERGO,which can enhance the catalytic performance and improve the current response.The linear range for detecting H2O2 was 25~8850 ?M and 8850~28850 ?M with a detection limit of 8.33 ?M(S/N = 3).The H2O2 biosensor was applied to the detection of H2O2 in milk samples.The recoveries were between 94.6 and 98.1% and the relative standard deviations(RSD)were between 2.8 and 6.5%,which provided a feasible detection strategy for H2O2 residue detection.2)N,S double-doped carbon nanofibers(N,S-CNFs)were successfully prepared by high temperature pyrolysis using bacterial cellulose as the C source and melamine and trimeric thiocyanate as the N and S sources.Benefiting from the unique structure of N and S double doping and their synergistic effects,N,S-CNFs not only have a large specific surface area but also have excellent electrical conductivity,so that the electrocatalytic activity of the carbon nanofibers is improved.The carbon material was used to construct a sensor for the detection pesticide of CBZ,which has a wide linear range of 0.523~104.60 ?M and a detection limit of 0.17 ?M(S/N = 3),showing excellent analytical performance.And successfully applied to the detection and analysis of CBZ in actual samples,the recoveries ware between 93.6~98.7% and the RSD ware lower than 6.66%.