ELECTROCATALYSIS OF ANODIC OXYGEN-TRANSFER REACTIONS - ALIPHATIC-AMINES AT MIXED SILVER-LEAD OXIDE-FILM ELECTRODES

Results are described from research directed to the discovery of new anode materials suitable for obtaining stable and sensitive response when applied at constant potential for the amperometric detection of organic amines. Voltammetric and amperometric results are compared for detection of selected organic amines in carbonate buffer (pH 10) at,mixed silver-lead oxide films prepared by electrodeposition on platinum substrates and by anodization of Ag-Pb alloys. Anodic response is observed at both electrodes for ethylamine, N-ethylmethylamine, trimethylamine, ethanolamine, and L-alanine. However, data indicate that the oxide electrode formed by anodization of Ag-Pb alloys is superior with regard to stability of response. On the basis of flow-injection detection using constant applied potential in carbonate buffer, linear dynamic ranges (r(2) > 0.99) are at least three decades for selected primary secondary, tertiary, alkanolamine, and amino acids in carbonate buffer (pH 10), with detection limits (S/N = 3) of ca. 0.3 mu M (i.e., 6 pmol per 20 mu l injection). Results are presented for the characterization of these films using x-ray diffractometry, x-ray photoelectron spectroscopy, and scanning electron microscopy.