Determination of formation constants of metal complexes by potentiometric stripping analysis

A method based on the data obtained from complexometric titration followed by potentiometric stripping analysis is developed. Optimization of the experimental conditions, namely: choice of the proper oxidant, deposition potential, plating time, concentration, and pH, considerably reduced the errors contributed by kinetic dissociation. This method was applied to ethylenediaminetetraacetic acid (EDTA) titration with lead and gave a formation constant for Pb‐EDTA that agreed well with literature values. The method may be applied to the determination of formation constants of 1 : 1 complexes with Kf values about 1020. The feasibility of the metal ion depends mainly on the solubility of the metal in the mercury in addition to its reversible behavior at the thin mercury film electrode.