Catalytic Effects in the Electrochemical Analysis of Arsenic Oxo Species

Electrochemical processes of arsenic species involve a combination of electron and oxygen transfer. Obtaining a current suitable for chemical analysis requires catalysis of the electrochemical reactions. Reduction of As(V) is very difficult and is practically limited to its adsorbate species. During voltammetric oxidation of As(III) on a Pt electrode, the catalyst is generated through the formation of the lower oxide of Pt. Intentional modification of the electrode surface with a specific catalyst is exemplified by deposition of a thin film of mixed-valent oxo ruthenium(II,III) cyanide. Noble metal surfaces such as Au(0) and Pt(0) exhibit catalytic properties as well. Various electroanalytical procedures have been proposed.