Preparation Of Graphene-Based Molecularly Imprinted Electrochemical Sensor And Its Detection Of Chlorpyrifos

With the worldwide ban on the production of highly toxic and residual pesticides,organophosphorus pesticides and chlorpyrifos have been widely used in agricultural production as excellent substitutes for herbicides and insecticides.However,these molecules pose significant health risks because they can be transferred to humans through bioaccumulation or indirect contact.Exposure to organophosphorus pesticide molecules can cause a range of health problems,including breathing difficulties,convulsions,and even death.Therefore,the use of organophosphorus pesticides has become a topic of concern for researchers and regulatory agencies worldwide.Currently,the methods for detecting chlorpyrifos include enzyme biosensors,high-performance liquid chromatography（HPLC）,and other methods.However,the detection methods are relatively cumbersome and not convenient enough.Therefore,a simple and rapid trace detection method for chlorpyrifos in environmental food is urgently needed.Firstly,this article mainly introduces the residues and detection methods of chlorpyrifos（CP）organophosphorus pesticide molecules,as well as the working principles of molecular imprinting technology and electrochemical sensors,and their feasibility analysis for the detection of residual pesticide molecules.Secondly,this article combines molecular imprinting technology and electrochemical sensor analysis methods to detect trace residues of CP pesticide molecules.With the high sensitivity and specificity of molecular imprinting technology,it also has the convenience,visualization,and miniaturization characteristics of electrochemical sensors.Through the synthesis of bifunctional monomer molecular imprinted films,it can improve the coagulability of polymer modified electrodes while increasing the density of imprinted sites.SEM,FT-IR,UV,and DPV techniques were used to characterize the surface morphology,elemental characteristic peaks,interaction between functional monomers and template molecules,and electrochemical characteristics of graphene based molecular imprinting of bifunctional monomers.A three-electrode system was constructed by modifying the glassy carbon electrode with graphene based molecular imprinting.The detection limit concentration for the target analyte reached 10^-9 mol·L^-1,A control group experiment was conducted to further verify the experimental results.After 8 days of testing,the bifunctional monomer modified chlorpyrifos electrochemical sensor retained 87.4%of the original current response.The experimental results show that the prepared modified electrode has good stability in the determination of template molecules（CP）.Thirdly,this article uses the high porosity and specific surface area of MOFs materials and graphene to prepare composite materials.Hydrogen bonds can be formed between the amino group of NH₂-Ui O-66 and chlorpyrifos to prepare higher density imprinted cavities.The composite materials prepared with GO have both high porosity and specific surface area,making it easier to form molecular imprinted cavities on the surface,adjusting the number of deposition circles,and optimizing the elution incubation time,The NH₂-Ui O-66/GO/GCE under the optimal conditions was prepared and tested by XRD and SEM,which proved that the preparation of the material was successful.Trace detection of chlorpyrifos was performed using a modified electrode,with a minimum detection limit of 10^-9 mol·L^-1 for template molecules.The electrochemical active areas of blank GCE and MOFs/GO materials electrodeposited glassy carbon electrodes were investigated.Finally,the Randles-Sevcik equation confirmed that the prepared NH₂-Ui O-66/GO/GCE had a higher electrochemical active area than blank GCE.Finally,Fe₃O₄ nanoparticles used in this paper have a large specific surface area,high surface activity,and strong adsorption capacity,which make them have great potential in electrochemical detection.At the same time,graphite powder is a fluffy fine powder with a large surface area,and has a strong combination of conductivity and chitosan adhesion,improving the conductivity and adhesion of modified electrodes.By preparing composite materials of Fe₃O₄/GO and GP-CS,while enhancing adsorption capacity and specific surface area,increasing the conductivity of the modified electrode and the adhesion between the material and the electrode,accelerating electron transfer,Fe₃O₄/GO and GP-CS modified electrodes were prepared under optimal conditions,and then MIPs electrochemical sensors were prepared by electrodeposition of p-phenylenediamine.SEM and electrochemical characterization showed that the preparation of the material was successful.The minimum detection limit for chlorpyrifos in a three-electrode system was 10^-9 mol·L^-1.In this paper,molecular imprinting technology,electrodeposition methods,and electrochemical sensor technology are combined to prepare three types of sensors,namely graphene modified MIPs,NH₂-Ui O-66/GO electrodeposited MIPs,Fe₃O₄/GO,and GP-CS electrodeposited MIPs modified electrodes.By optimizing the experimental scheme and exploring electrochemical characterization analysis,specific trace detection of chlorpyrifos pesticide residues was achieved.