EQUILIBRIUM STUDIES OF THE TERNARY COMPLEX-SYSTEMS M(N-(2-ACETAMIDO)IMINODIACETIC ACID OR AMINO-ACIDS() PLUS DIPICOLINIC ACID PLUS N)

Complex formation in the ternary systems M(n+) + dipicolinic acid + am ino acids or N-(2-acetamido)-iminodiacetic acid (H(2)ADA), where M(n+) = Cu-II, Zn-II, Ni-II, Co-II, Hg-II, Cd-II, Pb-II, UO2II, Y-III, and Ce-III, have been investigated pH-metrically in aqueous media at 25 de grees C and at ionic strength I = 0.10 mol dm(-3) (KNO3). The stabilit y constants of the different binary and ternary complexes formed in su ch systems have been determined and discussed in terms of the nature o f both metal ion and secondary ligand (amino acids or H(2)ADA). It was deduced that, except in the case of dicarboxylic amino acid, the stab ility of the ternary complex is lower than that of the corresponding b inary M(n+) + amino acid or H(2)ADA.