Collect. Czech. Chem. Commun. 1982, 47, 1802-1806

Isotachophoresis of complex ions

Petr Gebauer and Petr Boček

Institute of Analytical Chemistry, Czechoslovak Academy of Sciences, 611 42 Brno


The present paper quantitatively describes four fundamental types of the migration of complex anions in an isotachophoretic arrangement, observed experimentally, and suggests the possibilities of utilizing the differences in the migration behaviour for analytical separations. Kinetically inert complexes form stable zones under isotachophoretic conditions and their migration behaviour does not differ from isotachophoresis of simple ions. Kinetically labile complexes are in the dissociation equilibrium with the free metal cations and the free ligand and their progressive decomposition occurs in the course of the migration, i.e., the zone of the complex is not migrationally stable. By selecting operating conditions properly, in the first place the pH of the leading electrolyte, the migration stability of the zones of complexes can be influenced selectively in such a way that the decomposition of one of the complexes will be suppressed to a negligible extent while another complex will decompose totally in the course of the migration and will provide an equivalent zone of the free ligand. Various migration behaviour of the complexes can be applied in order that both required analytical separation may be obtained and the isotachophoregram may be evaluated quantitatively.