Study of cadmium complexation at high ligand concentrations

Abstract

Using square-wave voltammetry, cadmium complexation with chloride ions and small organic molecules has been studied at high ligand concentrations and high ionic strengths, i.e. conditions that can be found or expected in nature (seawater, body fluids, etc.) Over a relatively wide range of ionic strengths ( I = 0.5–6 mol l −1) the number of chloride complexes found and their stability constants were in a very good agreement with the literature data. With all organic ligands (glycine, diglycine and triglycine), three consecutive complex species have been found at I = 0.1 mol l −1 instead of two as published previously. The first stability constants were in satisfactory agreement with literature values. All measurements have been performed over ligand concentration ranges as wide as possible. Only in such a case can all the complexes be detected and their stability constants calculated.