The impact of intermetallic compounds Cu_xZn in the determination of free Zn~(2+) concentration with AGNES

摘要

Intermetallic compounds can interfere the determination of free Zn with AGNES (Absence of Gradients and Nernstian Equilibrium Stripping). The "trajectory" (plot of the retrieved currents in front of the deposition times) diverges from the "reference current" (i.e. that unaffected by the interference) at a critical time and eventually reaches steady state. Most experimental AGNES results are interpreted with a thermodynamic model, while others require kinetic considerations. We identify safe conditions for AGNES measurements and show that free Zn can be determined with the simplest implementation provided that total Cu concentration is less than 45 times that of free Zn.