ANALYTICAL APPLICATIONS OF MODIFIED LEAD DIOXIDE ELECTRODES

Electrochemical activity and stability of pure lead dioxide(PbO2) and lead dioxide incorporated with metal ions (As5+, B3+, Cr3+, Fe3+ and N i2+) were studied. Heterogeneous rate constants for oxidation of numer ous inorganic and organic compounds at PbO2 were compared with those a t mixed lead dioxide electrodes. Among the tested metal ions, it turns out that arsenic is one of the promising elements. The electrochemica l stability of he mixed oxide electrode prepared in an optimum conditi on, i.e., As5+/Pb2+ in the deposition solution, was increased compared to that of PbO2. For the application of the electrode material to ele ctroanalysis, detection of thiourea, for example, at PbO2, and As inco rporated lead dioxide electrodes(As/PbO2) as working electrodes in a t hin layer electrochemical cell for flow injection analysis(FIA) was in vestigated by a constant-potential amperometry. Sensitive detection of thiourea with a detection limit of 1.4 x 10(-7) M was achieved with P bO2 and As/PbO2 electrodes.