Study For Simultaneous Voltammetric Determination Of Multi-Component Analytes

In recent years, the electroanalytical chemistry has made great progress in method, technology and application. At the method, the requirement of sensibility and selectivity is increasing, there are many new electrode systems appearing which are from macroscopic to microscopic scale. At the technology, the interdiscipline of surface science, nanotechnology and physics spectra etc coupled with electrochemical interface can monitor the electrode reaction at the molecular and atomic level in living organism. At the application, it was for the moment showed the potential application value of some basic processes and molecular recognition ability in many fields such as life sciences, environmental science and medicine, which has attracted extensive attention. The study of simultaneous voltammetric determination electrical activity isomers and homologues at the nano-electrode interface has showed potential application prospects and academic significance. So, the preparation and application nanoelectrode need further study. In this thesis, we developed our work focusing on this hot issue, which has been dealt in the following part: 1. Simultaneous determination of dihydroxybenzene isomers using pre-anodized inlaying ultra-thin carbon paste electrodeIn this report, electrochemically pre-anodized inlaying ultra-thin carbon paste electrode (IUCPE) was fabricated onto the nichrome substrate. The pre-anodized IUCPE (PAIUCPE) exhibited good recognition ability toward dihydroxybenzene isomers. Three well-defined oxidation peaks of catechol (CC), resorcinol (RC) and hydroquinone (HQ) could be identified entirely at the electrode. The oxidation peak potential difference between HQ and CC was 113 mV, CC and RC 427 mV. The peak currents of dihydroxybenzene isomers increased linearly with increasing the dihydroxybenzene isomer contents. The proposed method can be applied to simultaneous determination of dihydroxybenzene isomers with higher selectivity and sensitivity.2. Simultaneous determination of tyrosine and typtophan at an inlaying super-thin carbon paste electrode modified with functional single-wall carbon nanotubes compound p-aminobenzene sulfonic acid A novel single-wall nanotubes compound p-aminobenzene sulfonic acid functional electrode (SWNTs/P-(pABSA))is prepared at an inlaying ultra-thin carbon paste electrode(IUCPE), the precursor film was formed by direct inlaying carbon paste onto nichrome substrate, and was used for simultaneous determination of tryptophan(Trp) and tyrosine(Tyr). The electrochemistry response of Trp and Tyr were studied at the SWNTs/P-(pABSA) by cyclic voltammetry and semi-differential voltammogram. Experiments indicated that the electrode exhibited an excellent elecocatalysis and enhancement of the current response for Trp and Tyr. The preparation of the SWNTs/P-(pABSA) was an economical, simple and convenient way. The proposed method can be applied to simultaneously determine of Trp and Tyr in compound amino acid injection.3. Simultaneous determination of nitrophenol isomers at glassy carbon electrode modified with functional single-wall carbon nanotubes compound p-methylpyridineCombine the molecule identification ability of conducting polymer with the peculiar properties of carbon nanotubes, a novel single-wall nanotubes (SWNTs) compound poly(p-methyl pyridine) modified electrode (SWNTs/POMP) is prepared at glass carbon electrode(GCE) by cyclic Voltammetry, and was used for simultaneous determination of nitrophenol isomers,The electrochemistry response of nitrophenol isomers were studied at the SWNTs/POMP by cyclic voltammetry and multiple semi-differential voltammogram. Experiments indicated that the SWNTs/POMP exhibited an excellent elecocatalysis and enhancement of the current response for nitrophenol isomers. The electrode showed good sensitivity, selectivity and stability.4. Simultaneous determination of nitrobenzoic acid isomers at glassy carbon electrode modified with functional single-wall carbon nanotubes compound poly(para-aminophenol)a novel single-wall nanotubes (SWNTs) compound poly(p-aminophenol) modified electrode (SWNTs/p-(PAP)) is prepared at glass carbon electrode(GCE) by cyclic Voltammetry, and was used for simultaneous determination of nitrobenzoic acid isomers, cyclic voltammetry and multiple semi-differential voltammograms were used to study their electrochemistry responses. Experiment indicated that the SWNTs/p-(PAP) exhibited an excellent elecocatalysis and enhancement of the sensibility. The electrode showed good sensitivity, selectivity and stability.5. Simultaneous determination of tryptophan and DL-5-hydroxytryptophan with an inlaying ultra-thin carbon paste electrode modified with functional single-wall carbon nanotubes compound p-aminobenzoic acid The unique electrode was constructed on the surface of inlaying uitra-thin carbon paste electrode (IUCPE) modified with functional single-wall carbon nanotubes compound poly(p-aminobenzoic acid) (SWNTs/PPAA/IUCP). Scanning electron microscope (SEM), electrochemical impedance spectroscopy (EIS) and voltammetry were employed to characterize the electrode configuration and electrochemical properties. The SWNTs/PPAA/IUCP electrode exhibited excellent recognition ability toward tryptophan (Trp) and 5-hydroxytryptophan (5-HTP). Two well-defined oxidation peaks of 5-HTP and Trp were observed at 0.569V and 0.963V. The oxidation peak currents increased linearly with increasing their contents. The proposed electrode could be used for the simultaneous voltammetric determination of Trp and 5-HTP in mixture without previous separation.