Metal Speciation in Polyelectrolytic Systems by Differential Pulse Anodic Stripping Voltammetry

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Abstract
The differential pulse anodic stripping voltammetry (DPASV) of a number of metal/polyelectrolyte complexes is studied, taking into account the (large) differences between the diffusion coefficients of the free and complexed metal. Zinc polymethacrylate, cadmium polymethacrylate and zinc polyacrylate systems are found to be labile under stripping voltammetric conditions. Over a wide range of metal-to-ligand ratios, their DPASV peaks are successfully analyzed in terms of a mean diffusion coefficient D. This D reflects the speciation of the metal over free and complexed form as governed by the stability of the metal/polyanion complex. For lead and cadmium polyacrylates, the variation of the DPASV peak height with polyion concentration is more involved since it cannot be explained on the basis of differences in diffusion coefficients and finite rates of complex association/dissociation.