Comparative study of cyclic voltammetry with potentiometric analysis for determining formation constants for polyaminocarboxylate–metal ion complexes

Abstract

Cyclic voltammetry offers a convenient route towards the determination of ligand protonation/deprotonation constants and also for metal–ligand complex stability constants in aqueous media. The utility of voltammetry is exemplified by a comparison of the metal–ligand stability constants of complexes of ethylenediamine (ED), ethylenediamine- N, N, N′, N′-tetra-acetic acid (H 4EDTA) and diethylenetriamine- N, N, N′, N″, N″-penta-acetic acid (H 5DTPA) with transition metals, with these stability constants being in good agreement with those obtained using potentiometric analysis. Further support for the usefulness of voltammetry as an analytical tool is the good correlation of the protonation constants for ( S, S)-ethylenediamine- N, N′-disuccinic acid with those determined potentiometrically.