Croatica Chemica Acta, Vol. 79 No. 1, 2006.
Original scientific paper
Comparative Evaluation of Scanned Stripping Techniques: SSCP vs. SSV
Raewyn M. Town
Herman P. van Leeuwen
Abstract
The characteristic features of scanned deposition potential curves constructed from stripping chronopotentiometry (SSCP) and various modes of stripping voltammetry (SSV) are critically evaluated. The strengths and weaknesses of each method for identification of metal ion speciation features and susceptibility to typical interferences are described for conventional (HMDE) and microelectrodes, i.e. irreversibility in the electron transfer reaction, multi-metal resolution, intermetallic compound formation, homogeneous kinetics, induced metal adsorption, and requirement for excess ligand to avoid saturation at the electrode surface during reoxidation. The most advantageous stripping modes are those in which practically complete depletion of the accumulated metal is achieved during the reoxidation step, i.e. SCP with low stripping current and DC-SV with slow potential scan rate. Under these conditions there is a straightforward quantitative relationship between the amount of metal accumulated and the analytical signal. The slow rate of oxidation with these modes renders them practically immune to induced metal adsorption; they have a lower requirement for excess ligand in the sample solution and greater resistance to both irreversibility in the electrochemical oxidation and to interference from intermetallic compounds. Even in the case of nonreversible electrode processes, or for systems limited by complex formation/dissociation kinetics, depletive scanned deposition potential stripping curves allow complexation parameters to be determined from the shift in half-wave deposition potential, analogous to the DeFord-Hume approach for conventional voltammetry. SSCP has greater sensitivity, and provides greater resolution in multi-metal systems than does depletive DC-SSV, while SSV provides useful complementary information in some cases.
Keywords
stripping chronopotentiometry; stripping voltammetry; metal speciation; microelectrode; irreversibility; heterogeneity
Hrčak ID:
2596
URI
Publication date:
22.4.2006.
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