Analytical Utility of the Iridium-Based Mercury Ultramicroelectrode with Square-Wave Anodic Stripping Voltammetry

Samuel P. Kounaves* and Wen Deng
Department of Chemistry, Tufts University, Medford, Massachusetts 02155

Abstract

The characteristics of the iridium-based hemispherical mercury ultramicroelectrode (Hg-UME) in conjunction with square-wave anodic stripping voltammetry (SWASV) have been investigated. Using Hg-UMEs of 5-10 mm radii, samples were analyzed without any added electrolyte, deoxygenation, or forced convection. The peak stripping currents displayed a linear relationship with deposition times varying from 1 to 1200 s. Peak potentials and current remained substantially unchanged with electrolyte concentrations of 1-10^-5 M. The reproducibility and useful lifetime of the Hg-UME was studied and found to be excellent over several days use. The application of SWASV theory for mercury film electrodes is shown to not entirely describe the response at the Hg-UME, especially at low square-wave frequencies.