| Project/Area Number |
02670979
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Physical pharmacy
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| Research Institution | Osaka University |
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Principal Investigator |
OHMORI Hidenbu Osaka University. Faculty of Pharm. Sci., Professor, 薬学部, 教授 (90028845)
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| Co-Investigator(Kenkyū-buntansha) |
OZAKI Shigeko Osaka University. Faculty of Pharm. Sci., Assistant, 薬学部, 助手 (00028854)
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| Project Period (FY) |
1990 – 1991
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| Project Status |
Completed (Fiscal Year 1991)
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| Budget Amount *help |
¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1991: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1990: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Keywords | Micro-macro composite electrode / voltammetry / dopamine / ascorbic acid / electrochemical analysis |
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| Research Abstract |
With a composite plane electrode constructed by compressing a micro-electrode between two macro-electrodes placed in close proximity to each other, the environment of solution near the surface of micro-electrode is expected to depend on the potential applied to the macro-electrodes. The experiments based on this expectation gave the following results.
(1)Fabrication of the micro-macro composite electrode : A platinum wire of 25mum phi was compressed between two glassy-carbon plates(area, ca. 0.08cm^2x 2)placed parallel to each other in a distance of about 75mum. Among more than 30 composite electrodes fabricated in this way, those electrodes in which the distance between the platinum wire and the glassycarbon plates is less than 25mum showed the expected electrochemical characteristics(see below).
(2)Electrochemical characteristics of the composite electrode : Cyclic voltammetry of[Fe(CN)_6]^<2+> (Fe(II))in aqueous solution was performed with the composite electrode. When the potential a
… More
pplied to the macro-electrodes was more positive than the oxidation potential of Fe(II), cyclic voltammetry of the solution with the micro-electrode showed a reduction wave due to FE(III)but essentially no oxidation wave of Fe(II). These results strongly suggest that the micro-electrode is located in the diffusion layer of the macro-electrodes and the composite electrode is adequate for the present purpose.
(3)Voltammetric determination of dopamine(DA)in the presence of ascorbic acid(AA) : Differential pulse voltammetry of DA at the micro-electrode was examined in the presence of AA with various applied potentials at the macro-electrode. With the composite electrode polished by a conventional method, the applied potential required for the macro-electrode to remove AA effectively from the surface of the micro-electrode was +0.40V(vs. Ag/AgCl) ; the lower limit of determination of DA was found to be 0.5mM in the presence of 10mM AA. When the surface of the macro-electrodes was treated by anodic oxidation in dilute sulfuric acid, AA in the system was removed by the macro-electrodes with applied potential as low as +0.10V ; under this condition, the lower limit for the determination of DA was 0.2mM in the presence of 20 mM AA. Less
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