Addressing temperature effects on metal chemodynamics studies using stripping electroanalytical techniques. Part 1: Lability of small complexes

• SSCP is used to analyse the temperature effects on the metal speciation dynamics.
• The metal complexes with small ligand become more labile upon the increase of T.
• The diffusion layer thickness and the association rate constant increase with T.
• For thin film Hg electrode, a calibration is required for each T of interest.

Temperature effects on metal speciation dynamics were studied using Stripping Chronopotentiometry at Scanned deposition Potential (SSCP). The temporal and spatial scales of this study are respectively O(10−1 s) and O(10−5 M), characteristics of the thin mercury film rotating disk, used as working electrode. The lability degree and the association rate constant were evaluated in the temperature interval of 15–40 °C for a significantly non-labile system, cadmium binding by nitrilotriacetic acid, and a quasi-labile system, lead binding by iminodiacetic acid. The results for both systems reveal that the lability of the metal complex significantly increases with temperature. This lability gain results from the thermal augmentation of the association rate constant and the broadening of the diffusion layer thickness.An evaluation of the metal calibration methodology for SSCP at different temperatures was conducted. It was found that although the variation of diffusion layer thickness can be correctly predicted, changes in standard reduction potential of the metals cannot, thus a calibration must be performed for each temperature studied.This work constitutes a first step toward the comprehension of the effect of temperature on metal chemodynamics.