ELECTROCATALYSIS OF POLY-THIONINE MODIFIE D MICROBAND GOLD ELECTRODE FOR OXIDATION OF REDUCED NICOTINAMIDE ADENINE-DINUCLEOTIDE

The electrocatalytic oxidation of NADH in phosphate buffer solution (p H = 7.0) by poly-thionine modified microband gold electrode was invest igated. The electrochemical polymerization of thionine in acetonitrile solution and the properties of the resulting films were studied. It w as found that the addition of acids such as CF3COOH to the medium mark edly facilitates the film formation. The poly-thionine film was charac terized by IR spectra. Two redox couple of poly-thionine in the potent ial range of -0.7-+0.5 V (vs. SCE) were observed, one of them possesse s the monomer-type activity. The peak potentials are E(pc)(I) = -0.03 V, E(pa)(I) = 0.05 V; E(pc)(I) = -0.24 V and E(pc)(I) = -0.17 V (vs. S CE, 25 degrees C). A slope of -29 mV/pH for the plot of E(o') vs. pH w as observed in acidic solution, whereas in alkaline solution the slope was -56 mV/pH.