The Preparation And Application In Analysis Of Modified Electrode Based On Nanomaterials And Polymer Film

Chemically modified electrode (CMEs) is a hot area of research in the field ofelectrochemistry and electroanalysis, owing to its outstanding advantages such as highsensitivity, feasible operation, low cost and so on. Applications of nanometermaterials in CMEs effectively improve the performance of the electrodes and extendthe application area of the nanometer materials. Graphene, as a new type of carbonnanomaterials with two-dimensional lattice, due to its unique structure and perfectproperties, has attracted much attention in the field of electrochemical sensor. Withthe help of the polymers that bear good conduction and stable chemical properties,graphene can be absord firmly to the surface of the electrodes, which not onlymagnitudes the surface area, but also strengthens signals of the current response andthe sensitivity of CMEs. In this thesis, three novel modified electrodes based ongrapheme, functionalized graphene and nanometer materials were fabricated and theirpotential applications in food and medicine analyses were also studied. The mainresults are expressed as follows:1. A newly-typed PNAI/GR-FA composite film modified electrode was successfullyprepared with ferrocenecarboxylic acid (FA), polyaniline (PANI) and chemicallysynthesized grapheme(GR) as modified materials. The morphology and structure ofthe prepared electrode were observed by scanning electron microscopy(SEM). Inoptimal reaction conditions, the electrochemical behavior of nitrite (NO2-) on themodified electrode was investigated by cyclic voltammograms (CV) and differentialpulse voltammertry (DPV). The results showed that the PNAI/GR-FA modifiedelectrode has excellent electrochemical catalytic behavior for the oxidation of NO2-inthe pH4.0Britton-Robinson buffer solution (BR) and the oxidation peak current wasdirectionally proportional to the concentration of NO2-in the range of4~300μmol·L-1with a detection limit down to1.2μmol·L-1(S/N=3). At the same time, the modifiedelectrode had high reproducibility and stability.2. A sulfanilic acid functionalized graphene sheets (AS-GS) was prepared bydiazonium sulfanilic acid and graphene oxide. AS-GS can alter the surface propertiesof graphene and prevent its agglomeration. Using AS-GS and Nafion as modified agents, a new type of composite film modified electrode was obtained. Theelectrochemical behaviors of caffeine(CAF) on the modified electrode wasinvestigated by the cyclic voltammetry (CV) and the differential pulse voltammetry(DPV). The prepared modified electrode displayed excellent electrochemical catalyticactivities toward the oxidation of caffeine under the optimum condition. The peakcurrent was linearly dependent on the CAF concentrations in the range of1～500μmol·L-1with a detection limit of5.31×10-7mol·L-1(S/N=3). The AS-GS/Nafioncomposition film modified electrode showed high sensitivity, favorable stability andreproducibility. It had been successfully applied in quick determination of CAF in thecola and functional beverages.3. AuNP-PGA/SGNF modified electrode was prepared by electrochemicalpolymerization in5mmol·L-1L-glutamate solution containing2mmol·L-1goldchloride acid and characterized by SEM. The modified electrode showed an efficientelectrocatalytic activity for the oxidation of acetaminophen (AC) in0.1mol·L-1PBSsolution of pH6.0and increased greatly the peak current and decreased apparently theredox potential of AC. Under the optimum condition, a good linear relationshipbetween the peak current and AC concentration was acquired in the range of2-73.33μmol·L-1with a detection limit of6.24×10-7mol·L-1(S/N=3). The modifiedelectrode could be used to simultaneously determine ascorbic acid(AA) andacetaminophen(AC) in real medicines with a satisfactory results.