Publication . Rocha, Luciana S.; Botero, Wander G.; Alves, Nuno G.; Moreira, José; Costa, Ana M. Rosa da; Pinheiro, J. P.
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.
