AN IRIDIUM BASED MERCURY ULTRAMICROELECTRODE - FABRICATION AND CHARACTERIZATION

A mercury ultramicroelectrode (Hg-UME) has been prepared by electrochemical deposition of mercury on an iridium substrate. The iridium UMEs can be prepared with radii of 1-20-mu-m using a molten salt etching solution of NaCl and NaNO3. The Ir and Hg UMEs have been characterized by cyclic voltammetry and chronoamperometry, and microscopically, and are shown to exhibit diffusional behavior in accord with microelectrode theory and geometry. The mercury is well adhering and stable for long periods of time, with no indication of amalgam formation. The iridium based Hg-UME appears to be a stable and rugged mercury electrode with potential uses for in situ and in vivo electrochemical analysis.