Research On The Detection Of Methyl Parathion And Mercury Ions In Food By Electrochemical Sensor Based On Carbon Nanocomposite

With the modernization of industry and agriculture,pesticide residues and heavy metal pollution have seriously threatened people’s life safety and become a major food safety problem worldwide.Therefore,there is an urgent need to develop efficient,sensitive,and low-cost strategies for the analysis of food contaminants.With the continuous development of nanotechnology,the detection performance of electrochemical sensors based on nanomaterials has been significantly improved,which are widely used in the analysis of food contaminants.In this paper,based on the research background of electrochemical sensors,combined with the advantages of carbon nanocomposites,sensitive and low-cost detection of typical organophosphorus pesticides（methyl parathion,MP）and heavy metal Hg²⁺were realized.The main research contents and results are as follows:（1）A hydrophobic carboxyl functionalized phosphonium-based ionic liquids（ILs）（（5-carboxypentyl）triphenylphosphonium bis（trifluoromethyl）sulfonyl）amide,TPP-HA[TFSI])was synthesized through a simple hydrothermal approach.Based on theπ-πand cation-πinteractions with multi-wall carbon nanotubes（MWCNTs）,a TPP-HA[TFSI]@MWCNTs composite was prepared to immobilize hemoglobin（Hb）to fabricate a simple and effective electrochemical sensing platform for the detection of MP.The TPP-HA[TFSI]@MWCNTs substrate synergistically provided a favorable biological microenvironment for Hb,the large specific surface area and high conductivity characteristics promoted the exposure of Hb electroactive centers and direct electron transfer,effectively amplifying the electrochemical signal and improving the detection sensitivityof MP.The constructed electrochemical sensor had a wide linear range(2-14ng m L^-1)and a low limit of detection(LOD,0.62 ng m L^-1)for MP with good repeatability,reproducibility,stability and anti-interference ability,and had acceptable recovery in the detection of vegetable sample,indicating that TPP-HA[TFSI]@MWCNTs was an effective immobilization substrate for biological components and had broad application prospects in the construction of electrochemical sensing interfaces.（2）An electrochemical sensing interface based on Zr O₂/nitrogen-doped three-dimensional porous carbon nanocomposites（Zr O₂/N-3DPC）was constructed by drop casting and electrochemical deposition methods for trace detection of heavy metal Hg²⁺.N-3DPC had an open pore structure,large specific surface area,multiple continuous mass transfer channels and active sites,which facilitated the diffusion and transport of electrons and ions at the sensing interface,and provided a strong attachment platform for the electrochemical deposition of Zr O₂.Benefiting from the good adsorption and catalysis for Hg²⁺,Zr O₂/N-3DPC/GCE had a lower LOD(0.062μg L^-1),a wide linear range of 0.1-220μg L^-1,good repeatability,reproducibility,stability and anti-interference,and has been successfully used for the detection of Hg²⁺in seafood and tap water,with low relative standard deviation（≤4.3%）and satisfactory recovery（97.1-103.1%）,providing a new idea for the application of Zr O₂/N-3DPC in the field of heavy metal ion detection.