USAGE OF A BISMUTH ALLOY ELECTRODE FOR VOLTAMMETRIC ANALYSIS

摘要

Liquid mercury and liquid diluted mercury amalgams have been the major electrode systems employed in voltammetry and related methods. This is mainly due to their high overvoltage to hydrogen, which enables the determination of heavy metals (zinc, nickel and cobalt etc.) and other species with high negative half wave potentials. The toxicity of mercury and liquid diluted mercury leads to ever increasing restrictions in the their use. The use of such systems may even be forbidden in the future at least in online systems for work in the field. Recent work, carried out in our laboratory, has demonstrated that a non-toxic solid dental amalgam may be used as the electrode material, conveniently replacing mercury. An extension of this work has shown that electrode materials comprising a metal or a compound with low hydrogen overvoltage change their hydrogen overvoltage properties substantially when contaminated with even small amounts of metals or compounds which show high hydrogen overvoltage. This extends greatly the range of potentially available electrode systems and thereby analytical possibilities of voltammetry.