Voltammetric techniques are powerful tools for the determination of heavy metal ions in different media. They find wide application in some metal-ion speciation schemes, particularly those used for aquatic systems and sediments. Furthermore, they are appropriate for the study of the interactions between metal ions and either natural or synthetic polyelectrolytic macromolecular ligands at very low concentrations. Electrode adsorption is a typical complication in such studies. In order to cope properly with this problem, theoretical and experimental efforts are necessary. In this article, some guidelines and procedures are given to account for the adsorption of macromolecules on a mercury electrode and the induced adsorption of the metal ion, and on how to minimize the effects on the voltammetric response of variations in pH (and other protolytic parameters) and the adsorption of metal ions by cell components.
