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

Adsorption of a number of flavins. phenazines, phenoxazines, and phenothiaz ines on zirconium phosphate (ZP) was carried out in aqueous solution. The a dsorbed organic dyes on ZP were used to prepare modified carbon paste elect rodes. The electrochemical properties of the immobilized dyes were investig ated and also their possible use to electrocatalytically oxidize NADH. The formal potential(E-0s) of most of the adsorbed flavins;ins. phenoxazines, a nd phenothiazines shifted markedly towards more positive potentials compare d 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 pres ent good electrochemical response nor electrocatalytic activity for NADH ox idation 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.