Determination of stability constants of complexes of M_iK_jH_kL type in concentrated solutions of mixed salts

摘要

This paper suggests a non-conventional approach towards the correct determination of stability constants K_(ijk) of mixed complexes from the results of potentiometric titrations. The method is based on inaccurate (in principle) results of titrations made in isomolar titrand-titrtant systems. The data thus obtained are validated on the basis of relationships between log K_(ijk) and relative error (%e) of the determination of an analyte concentration. Accurate values for K_(ijk) are calculated for the set (ijk) of possible complexes. The accuracy depends on the degree of linearity between the variables considered. The model obtained was thoroughly tested on the system containing malonic acid together with sodium and potassium nitrates.