Preliminary electrochemical study of phenothiazines and phenoxazines immobilized on zirconium phosphate

The electrochemical properties of one phenothiazine (Methylene Blue) and one phenoxazine (Nile Blue) dye immobilized on zirconium phosphate were investigated by incorporation into a carbon paste electrode. The dyes presented a very stable redox property. The midpoint potentials (E-m) were 150 and 50 mV vs. SCE for Methylene Blue and Nile Blue, respectively. The composition and pH of the supporting electrolyte did not affect the E-m, in contrast to those observed for the dyes in solution phase or when adsorbed on carbon. These electrodes showed a good activity in a test made for electrocatalytic oxidation of NADH. (C) 1997 Elsevier Science S.A.