Ionophoretic technique in the study of mixed complexes (Mnitrilotriacetatehistidinate systems)

Abstract

A new method involving the use of paper electrophoresis is described for the study of the equilibria in mixed-ligand complex systems in solution. This technique is based on the movement of a spot of metal ion under an electric field with the complexants added in the background electrolyte at pH 8.5. The concentration of primary ligand (NTA) was kept constant while that of secondary ligand histidine was varied. The plots of log [histidine] against mobility were used to obtain information on the formation of the mixed complex and to calculate its stability constants.The binary equilibria M(II)histidine and M(II)NTA have also been studied since it is prerequisite for the investigation of mixed complexes. The stability constants of the complexes, Metalnitrilotriacetatehistidinate have been found to be 5.61, 5.31, 3.77, 3.94 (log K values) for Cu(II), Uo(in2)(II), Co(II) and Zn(II) complexes respectively at μ = 0.1 and temperature of 35°C.