Pseudopolarography at the Mercury Hemisphere Ultramicroelectrode. Theory and Experiment

Samuel P. Kounaves
Department of Chemistry, Tufts University, Medford, Massachusetts 02155

Abstract

The theoretical expressions for pseudopolarography at a hemispherical mercury ultramicroelectrode are derived and compared with experimental data at varying deposition times and low and high electrolyte concentrations and with previous theory for other electrodes. It is shown that, even though several of the physical conditions are different, the behavior of both the pseudopolarographic half-wave potential and the limiting peak stripping current is similar to that for the HMDE. The fit between the theory and the experimental data was excellent. A correction term for the increase in the limiting current due to the deposition occurring at the ultramicroelectrodes during a slow scan is described. The deviation of the limiting peak stripping current with increasing negative deposition potentials seen in this and precious works is discussed and attributed to adsorption of trace organics on the mercury electrode surface.