Electrochemical study of flavins, phenazines, phenoxazines and phenothiazines immobilized on zirconium phosphate

Adsorption of a number of flavins. phenazines, phenoxazines, and phenothiazines on zirconium phosphate (ZP) was carried out in aqueous solution. The adsorbed organic dyes on ZP were used to prepare modified carbon paste electrodes. The electrochemical properties of the immobilized dyes were investigated and also their possible use to electrocatalytically oxidize NADH. The formal potential(E-0s) of most of the adsorbed flavins;ins. phenoxazines, and phenothiazines shifted markedly towards more positive potentials compared with their values in solution. The pH of the contacting solution did not affect their E-0-values between pH I and 9. The phenazines did neither present good electrochemical response nor electrocatalytic activity for NADH oxidation and their E-o'-values remained pH dependent. In contrast. adsorbed flavins, phenoxazines. and phenothiazines presented good electron transfer rates between the: electrode and the adsorbed molecule dye at pH 7.0.