Fabrication Of New Types Of Electrochemical Sensing Surface Base On Self-Assembly Technology And Its Recognition Analysis Application

Fabrication of new types of electrochemical sensing surface is currently an activearea of electrochemistry. The most prominent feature is that it can be designed accordingto our demand, and has shown splendid prospects in sensitivity and selectivity. With thedeepening research of nano-material, nano-material modified electrode has become a hottopic in electrochemitry in recent years.This thesis focused on designing and application of new electrochemical sensingsurface. Self-assembly technology was used to construct electrochemical sensing surface.Three new electrochemical sensors were fabricated. Based on which, new analyticalmethods were provided and applied to detect environmental pollutants, biologicalmolecules and drug. More details are as follows:In chapter one, a detailed summarization was given on the fabrication,modification and analytical application of chemically modified electrode.In chapter two, a self-assembled monolayer of captopril was fabricated on a goldelectrode. Cyclic voltammetry (CV) and A.C. Impedance were used to study the ionicrecognition property of captopril modified gold electrode. Research showed that therewas specific recognition between captopril self-assembled film and Pb2+. Base on this, ahigh sensitive and selective method for the determination of Pb2+was proposed, and wasappied in the analysis of Pb2+in tap water with satisfied results.In chapter three, a monolayer of2,2’-Dithiodipyridine was prepared on a goldelectrode through self-assembly technique. Characterization of the modified electrode wasperformed by using CV and A.C. Impedance. The electrochemical behavior ofdopamine(DA) and ascorbic acid (AA) on the modified electrode were studied.Well-separated DA and AA voltammetric peaks were observed at the2,2’-Dithiodipyridine self-assembled electrodes in the acetate solution at pH4, with thedifference of peak potentials of0.35V. Therefore, a high selectivite method wasestablished for determination of DA in present of high concentration of AA. The detectionlimit was8.0×10-7mol/L. The apparent charge transfer rate constants (kapp) of AA and DAon the modified electrode were evaluated by using EIS measurements as1.65×10-8and8.11×10-8cm.s-1, respectively. In chapter four, nickel oxide/multi-walled carbon nanotubes composite modifiedelectrode was constructed on the glassy carbon electrode by ion exchange andelectrodeposition. The electrochemical methods and SEM were used to characterize thecomposite modified electrode. It was found that the modified electrode could catalyze theoxidation of melamine in basic solution, and the oxidation peak potential was+0.6V.Based on the catalytic behavior, a new amperometric method for the determination ofmelamine was established, with the detection limit of5.0×10-7mol/L. Furthermore,catalytic oxidation performance of modified electrode was also observed when sulfhydrylcompound captopril. A rapid method for captopril detemination was provided with thedetection limit of1.2×10-7mol/L, and was appied for the analysis of content of captoprilin uric and serum samples with satisfied results.