Studies on metal-diethylenetriamine pentaacetic acid complexes as ligands

Potentiometric studies have been carried out on H3ML complexes where M represents divalent metal ions Cd, Hg, Co, Ni, Cu, Ca and Ba and L represents Diethylenetriamine pentaacetic acid (DTPA) using pH-titration technique. The protonation constants of H3ML complexes in solution have been determined at an ionic strength µ= 0.1 M KNO3 at 200C and 400C.The values of overall changes in free energy (?G), enthalpy (?H) and entropy (?S) accompanying complex formation have also been evaluated.These values are found quite favourable for the systems under study.