Fabrication Of Novel Carbon Nanomaterial-based Electrodes And Their Applications In The Analysis Of Foods And Drugs

New facile approaches have been successfully developed for the rapid preparation of new carbon-based nanocomposite electrodes for electrochemical sensing. In our study, novel methods have been employed for the synthesis of the new carbon-based composites as well as the fabrication of electrodes. The analytical performance of these carbon-based electrodes have been demonstrated by measuring food or drug samples in connection with capillary electrophoresis (CE) and electrochemical detection (ED).In Chapter One, the types and characteristics of the current carbon-based nanocomposites were briefly reviewed. Recent studies and developments on the preparation methods of these composites and electrochemical applications of these composite electrodes were mainly discussed.In Chapter Two, a facile approach based on water-vapor-initiated polymerization of ethyl2-cyanoacrylate (ECA) has been successfully developed for the rapid preparation of carbon nanotube/poly (ethyl2-cyanoacrylate)(CNT/PECA) composite for electrochemical sensing. The novel electrodes were fabricated based on in situ polymerization of the CNT/EC A mixture packed in the bore of fused silica capillaries. The morphology and structure of the composite were investigated by scanning electronmicroscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The results indicated that the CNTs were well dispersed and embedded throughout the PECA matrix to form an interconnected CNT network. The analytical performance of this unique CNT-based detector has been demonstrated by separating and detecting six flavones and Fructus Sophoraein sample in combination with capillary electrophoresis (CE). The advantages of the CNT/PECA composite detector include lower operating potential, higher sensitivity, low expense of fabrication, satisfactory resistance to surface fouling, and enhanced stability; these properties indicate great promise for a wide range of applications.In Chapter Three, a facile approach based on in situ chemical reduction has been successfully developed for the facile preparation of graphene-copper nanoparticle composite for electrochemical sensing. This novel composite was prepared by the in situ chemical reduction of a mixture containing graphene oxide and copper(II) ions using potassium borohydride as a reductant. Then it was mixed with paraffin oil and packed into one end of a fused capillary to fabricate microdisc electrodes. The morphology and structure of the graphene-copper nanoparticle composite were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fouriertransform-infrared spectroscopy (FT-IR). The results indicated that copper nanoparticles were successfully deposited on graphene nanosheets to form a well interconnected hybrid network. The analytical performance of these unique graphene-copper nanoparticle composite paste electrodes was demonstrated by sensing five carbohydrates and food samples in combination with cyclic voltammetry (CV) and capillary electrophoresis (CE). The advantages of the composite detectors include higher sensitivity, satisfactory stability, surface renewability, bulk modification, and low expense of fabrication. They should find applications in microchip CE, flowing-injection analysis, and other microfluidic analysis systems.In Appendix One, a CE-ED system was established for food and drug study. Details about the system, such as its configuration, apparatus parameters, installation, working conditions, and operation procedures were introduced.In Appendix Two, a self-assembly three-dimensionally adjustable device for the amperometric detection of capillary electrophoresis was described. Details about the device, such as its schematics, configuration, and operation procedures were introduced.