APPLICATION OF MULTIVARIATE CURVE RESOLUTION TO VOLTAMMETRIC DATA .1.STUDY OF ZN(II) COMPLEXATION WITH SOME POLYELECTROLYTES

Multivariate curve resolution is applied to the study of Zn(II) comple xation with anions of polymethacrylic acid and polyacrylic acid in aqu eous solution containing 0.01 M KNO3. Data matrices obtained by differ ent electrochemical techniques (normal pulse polarography, reverse pul se polarography, differential pulse polarography and differential puls e anodic stripping voltammetry) and for different ligand deprotonation degrees have been analysed individually and simultaneously by a proce dure which consists of using several chemometrical techniques based on factor analysis: principal component analysis, evolving factor analys is and multivariate curve resolution with alternating least-squares op timization. These techniques were used to investigate the number of sp ecies present in the systems, their concentration profiles at increasi ng ligand concentration and their individual voltammograms together wi th the global (apparent) stability constants K and the ratio of diffus ion coefficients of the individual species. The comparison of the resu lts obtained by soft (model free) and hard (model postulated a priori) modelling for the systems investigated is discussed.