Studies On Multiwalled Carbon Nanotubes Modified Electrodes And Their Application In Pesticide Determination

Carbon nanotubes(CNTs) are arrangements of carbon hexagons that are formed into tiny tubes,and both ends of each single tube are closed with caps formed by carbon rings, CNTs can be used as electrode materials with useful properties for electrochemical and bioelectrochemical applications.The extraordinary electronic property of CNTs enables them to facilitate the electron transfer when they act as electrode materials.Furthermore, the properties include excellent adsorption capability,great specific surface and various functional groups linked on CNTs have endued them with special electrocatalytie effect to the electrochemical behavior of some species.Thus,CNTs modified electrodes exhibit superior electrochemical properties to many other electrodes.And increasing attention is focused on their application in pesticide determination.In this thesis,we studied on fabricating different multiwalled carbon nanotubes modified electrodes which have been successfully used to determine pesticide.The main researches were summarized as follows:(1) We demonstrated SPE of nitroaromatic OP compounds to MWCNTs using electroactive methyl parathion(MP) as a model analyte and MWCNTs as sorbent. Combining the SPE and the SWV opens new opportunities for fast,simple,and sensitive analysis of OP compounds.And the detection limit isμg·mL^-1.(2) A new enzyme biosensor based on immobilization of AChE onto a multiwalled carbon nanotube(MWCNTs) modified electrode is prepared by controllable adsorption of the MWCNTs onto the hexyl mercaptan(C₆H₁₃SH) self-assembled monolayers (SAMs) through hydrophobic interaction.It has been successfully used to determine the carbaryl,a model of carbamate compounds.The proposed biosensor shows acceptable stability and sensitivity,and has potential application in AChE-inhibitors (organophosphate or carbamate compounds) analysis and environmental monitoring.(3) We have explored a new strategy to deposit gold nanoparticles on the side wall of MWCNTs as multiwalled carbon nanotubes/gold(MWCNTs-Au) nanocomposites by one stepreaction with NaBH₄ as reductant and stabilized with sodium citrate.Then a new amperometric acetylthiocholine sensor is devised for immobilization of acetylcholinesterase (ACHE) to the MWCNTs-Au nanocomposites modified glassy carbon electrode(GCE). The developed biosensor exhibits good reproducibility and acceptable stability,thus providing a new promising tool for analysis of enzyme inhibitors.(4) Multiwall carbon nanotubes(MWCNTs)-β-cyclodextrin(β-CD) composites have been successfully synthesized through combining polymer wrapping and layer-by-layer self-assembly techniques.Then a new amperometrie acetylthiocholine sensor was devised for immobilization of acetylcholinesterase(ACHE) to the MWCNTs-β-CD composites modified glassy carbon electrode(GCE).It has been successfully used to determine the dimethoate,a model of organophosphate pesticides. The developed biosensor exhibits good reproducibility and acceptable stability,thus providing a new promising tool for analysis of enzyme inhibitors.