Fabrication And Application Of Carbon Fiber Disk Ultra-microelectrode

Ultramicroelectrodes have been studied by electrochemistry and electroanalysischemistry workers over the recent years. The advantages arising from thesesmall-sized electrodes, including enhanced mass transport, reduced iR drop anddouble-layer charging effects, significantly enhance conventional electrodebehaviour. A decrease in electrode dimensions has also allowed measurements to bemade in microenvironments such as single cells and probes of this type may be usedin living tissue as they cause minimal physical damage. Ultramicro-modifiedelectrodes have a lots of good characteristics both from the ultramicro-electrodes andmodified electrodes. They can reduce detection limit,enhance sensitivity andselectivity and extend linear range. In this report, with the use of cyclic voltammetryand square wave voltammetry, Hg-Bi modified carbon fiber ultramicro-electrode andChitosan-Prussian blue modified carbon fiber ultramicro-electrode were made andwere investigated as a tool to detect Pb（II）, Cd（II） and4-nitrophenol.1.In this paper, a novel and simple method has been developed for the fabricationof carbon fiber ultramicro-disk electrode. With the use of cyclic voltammetry,westudied the voltammetry response, effective radius and stability of the carbon fiberultramicro-disk electrode. Results showed that:the voltammetry response of thecarbon fiber ultramicro-disk electrode made by us is the classic"S"; the effectiveradius are2.47μm,2.47μm and2.22μm which are close to the virtual radius; thegraphs of cyclic voltammetry almost have no change after one week, two weeks andthree weeks in the0.001mol L^-1K3Fe（CN）3.2.In this paper, a new and low cost preparation method for the determination ofPb（II） and Cd （II） in aqueous solution has been developed, based on the square wave anodic stripping response at Hg-Bi modified carbon fiber ultra-microelectrode.Thiselectrode was constructed in situ by depositing Hg, Bi and the target metals byreduction at-1.1V on the carbon fiber ultra-microelectrode. Operational parameterssuch as deposition time, deposition potential, the pH of buffer solution, the Hg-Biconcentration and the mass ratio of Hg-Bi were optimized for the determination oftrace metals. Under the optimal conditions, the detection limit, the linear range,stability, and recovery have been investigated. The detection limits were31ng L^-1forPb（II） and39ng L^-1for Cd（II）.3.In this paper, Chitosan-Prussian blue modified carbon fiber diskultramicro-electrode was made to detect4-nitrophenol in waster water. Operationalparameters such as deposition potential, deposition time, the pH of buffer solution andthe volume ratio of1mmol L^-1PB and0.1%CS were optimized for the determinationof4-nitrophenol. Under the optimal conditions, the detection limit, the linear range,stability, repeatability, interference and recovery have been investigated. Thedetection limit is0.068μmol L^-1for4-nitrophenol.