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.