Determination of stability constants by semi-integral analysis of voltammograms obtained with a computerized electrochemical system

A versatile computerized electrochemical system is used for the determination of stability constants of lead(II) propanoate and 2-hydroxypropanoate complexes by semi-integral linear sweep voltammetry. Semi-integral voltammograms are analogous in characteristics to d.c. polarograms, and the half-wave potentials (E_{$\text{1}\text{2}$}) and limiting currents (i₁) for a depolarizer can be obtained by nonlinear least-squares fitting of semi-integrally transformed voltammograms. An advantage of the proposed method is that E_{$\text{1}\text{2}$} and i₁ values are obtained from a single mercury drop (hanging or dropping mercury electrode); working time is reduced while accuracy and precision are maintained. The computer-controlled system provides automated reagent addition, signal generation, response measurement and sampling, data evaluation, etc. The results agree well with those obtained by the usual d.c. polarographie method.