LIGAND SIZE POLYDISPERSITY EFFECT ON SSCP SIGNAL INTERPRETATION

The present study aims to establish unambiguously the conditions required for the validity of the average diffusion (D¯) approximation in fully labile systems with significant ligand size polydispersity. The average diffusion coefficient is a key parameter in mass transfer that affects signal interpretation in dynamic electroanalytical techniques. To achieve this goal, the binding of Cd(II) and Pb(II) to binary and ternary mixtures containing chemically homogenous (PSS)n-COOH polymers (ligand excess conditions were required) of different sizes (4, 10 and 30 KDa) was evaluated. It was experimentally evidenced that the average diffusion coefficient (D¯), can indeed be computed as the weighted average of several metal-polymer complexes of diverse sizes.