Voltammetric study of bathocuproine disulphonate/copper system

The cathodic stripping voltammetry of copper in the presence of a Cu(I) ligand probe (bathocuproine disulfonate - BCS) is investigated. The Cu(I)-BCS and Cu(II)-BCS complexes formed are reduced, at approximately −0.55 V and −0.90 V against Ag/AgCl, respectively. The reduction of Cu(I)-BCS is accompanied by disproportionation to Cu(0) and Cu(II) and Cu(II)-BCS reduction to Cu(0) at potentials of about −0.55 V and −0.90 V vs. Ag/AgCl, respectively. The reduction mechanism of both complexes was recognized as an irreversible redox reaction followed by a chemical dissociation reaction (EC mechanism). The BCS ligand shows strong adsorption on the mercury drop electrode and is a selective ligand for Cu(I) ions, especially when EDTA is added to the solution. By extending the applied accumulation time, adsorptive cathodic stripping voltammetry offers the possibility to study Cu(I) and Cu(II) redox speciation in the nmol concentration range in the environment and in biological matrices.