Ionophoretic studies on mixed metal--nitrilotriacetate--penicillamine complexes.

Paper ionophoresis is described for the study of equilibria in a mixed ligand complex system in solution. This method is based on the movement of a spot of metal ion in an electric field with the complexants added in the background electrolyte at pH 8.5. The concentration of the primary ligand (nitrilotriacetate) was kept constant, while that of the secondary ligand (penicillamine) was varied. The stability constants of the metal-nitrilotriacetate-penicillamine complexes have been found to be 6.26 +/- 0.09 and 6.68 +/- 0.13 (log K values) for Al3+ and Th4+ complexes, respectively, at 35 degrees C and ionic strength 0.1 M.

Paper electrophoresis in the study of mixed ligand complexes in solution. The system Fe(III)- and Cr(III)-methyl cysteine-penicillamine.

A method involving use of paper electrophoresis is described for the study of equilibria in mixed ligand [methyl cysteine-penicillamine] complex systems in solution. The concentration of the primary ligand methyl cysteine was kept constant, while that of secondary ligand penicillamine was varied. The plots of -log [penicillamine] against mobility were used to obtain information on the formation of mixed complex and to calculate its stability constants. The binary equilibria M(III)-methyl cysteine have also been studied since this is a pre-requisite for the investigation of mixed complexes. The stability constants of [Fe(III)- methyl cysteine-penicillamine] and [Cr(III)-methyl cysteine-penicillamine] complexes were found to be 7.40 +/- 0.13 and 4.80 +/- 0.07 (log K values) for Fe(III) and Cr(III) complexes, respectively, at mu = 0.1 mol/L and at a temperature of 35 degrees C.