Electrochemical Detection of Cadmium and Lead Complexes with Low Molecular Weight Organic Acids

The Cd and Pb complexes with oxalic (OA) and citric acid (CA) were detected in model and soil solutions using cyclic and stripping voltammetry. A mixed complex consisting of Cd, Pb, and OA was found; its peak potential varied from -582.0 to -542.5 mV (vs. Ag/AgCl/KCl(3 mol L-1)). For mixed complex formation, the presence of PbOH+ species and Cd 21 in oxalic acid solution was necessary. Only the 'simple' complexes of CA with Pb and Cd were found in the model solution. The existence of all investigated metal complexes is confined to neutral pH range. ne mixed complex was also found in real soil solutions.