Adsorptive square-wave voltammetry of metal complexes. Effect of ligand concentration: Part III. Theory

The theory of adsorptive stripping square-wave voltammetry is extended to the case in which the products are a reduced complex with lower ligand/metal stoichiometric ratio than the oxidised reactant and the released ligand, which can be in solution or adsorbed. The dependences of peak currents and peak potentials on the reversibility of redox reactions and on the reaction mechanism are analysed and the effect of ligand concentration and the complex stoichiometry are considered. Diagnosis criteria for the selection of optimum square-wave parameters in view of analytical applications are presented. It was found that the SW voltammetric signal of reversible redox reactions of adsorbed species can be considerably enlarged if the adsorbed product is chemically related to a soluble species.