Chronopotentiometric stripping analysis as a probe for copper(II) and lead(II) complexation by fulvic acid: Limitations and potentialities

Fulvic acid exerts its influence only in the stripping step of chronopotentiometric stripping analysis (CPSA). Oxidation of reduced metal accumulated at a mercury-drop electrode is facilitated in the presence of fulvic acid, thus causing a reduction in the stripping time relative to that for a ligand-free solution, even when the same total amount of metal is oxidised. Data must be interpreted with caution; use of the term `labileʹ metal can be very misleading. CPSA is a potentially powerful tool to probe metal ion complexation over a wide range of ligand-to-metal ratios, allowing independent variation of both the total amount of metal oxidised and its rate of oxidation. The characteristic stripping peak parameters (stripping time, peak potential, and peak half-width) give information on the apparent stability and heterogeneity of the complexes formed by fulvic acid with copper(II) and lead(II).