|Budget Amount *help
¥2,100,000 (Direct Cost : ¥2,100,000)
Fiscal Year 1994 : ¥600,000 (Direct Cost : ¥600,000)
Fiscal Year 1993 : ¥1,500,000 (Direct Cost : ¥1,500,000)
1.Copper oxide (CuO) on electrode surface has been found to be essential for catalytic oxidation of carbohydrates under strongly alkaline conditions. In this catalytic reaction, alkoxide formation between highly oxidized Cu (III) and acid-dissociated alcolate groups and the intra-complex electron transfer from alcolate to Cu (III) play important roles. During the present catalytic oxidation, glucose for example is oxidized into formate via 12-electron transfer. The fact that copper oxide is such effective catalyst for multiple electron oxidation of carbohydrates means that CuO modified electrodes can be expected as devices for highly sensitive detection of carbohydrate under constant potential amperometry, in which adsorptive inhibition of electrocatalytic activity encountered for Au and Pt electrodes will not observed.
2.In order to fabricate highly active CuO-modified electrode, several pretreatments for the surface oxidation of Cu electrode have been examined, which has revealed the
followings. (1) : thoroughly polished metallic Cu electrode is inactive for carbohydrate oxidation, (2) : electrochemical oxidation of Cu results in the formation of a reticulated cracked structure over the electrode surface, in which copper oxide formation occurs, and the micro-structure remains to some extent by slight polishing, and (3) : mild air-oxidation of the slightly repolished electrode at 100ﾟC arrows sufficiently active and smooth copper oxide formation, which is suitable for a flow-through detector.
3.The air-oxidized Cu electrode arrows highly sensitive detection down to 100 fmole as glucose in HPLC,which is the best sensitivity as direct detection of carbohydrates. The electrode has long-time stability over 1 month without significant decrease in the catalytic activity.
4.Problems to be solved in future would be (1) : to elucidate microscopic reaction process catalyzed by copper oxide, (2) : characterization of the micro-structure of copper oxide-modified electrodes, (3) : improvement for highly sensitive detection of origosaccarides, and (4) : improvement for selective detection of carbohydrate in the presence of amines which are also oxidized at copper oxide electrodes. Less