COMPLEX EQUILIBRIA IN CAPILLARY ZONE ELECTROPHORESIS AND THEIR USE FOR THE SEPARATION OF RARE-EARTH-METAL IONS

The separation of lanthanides by capillary zone electrophoresis is carried out by addition of a complex forming agent to the separation buffer, thus generating charge and mobility differences between the species. The choice of a suitable ligand and especially the precalculation of the optimum ligand concentration is possible if the stability constants of the complexes are known. In this paper the relation between the calculated concentrations and the quality of separation at these concentrations is demonstrated. Furthermore, the influence of pH on the separation with hydroxyisobutyric acid is investigated as an example.