THEORETICAL ESTIMATION OF CAPILLARY ZONE ELECTROPHORESIS BEHAVIOR OF METAL-COMPLEXES USING MULTIVARIATE REGRESSION-ANALYSIS

The migration of lanthanide metal ions complexed with aminopolycarboxylic reagents (ethylenediaminetetraacetic acid and chemically similar analogues containing varying degrees of basicity and size) in capillary zone electrophoresis was investigated. Electrophoretic mobilities were measured for a series of complexes in berate buffer electrolytes of variable pH and buffer concentration (62 different compositions). A migration model was developed to relate the electrophoretic mobility with charge density parameters of a metal complex (the net charge, the stability constant and ligand structural increments) and electrophoretic system variables such as the electrolyte pH. The predictive ability of the derived regression equation was evaluated in terms of its statistical significance. The good agreement observed between the calculated electrophoretic mobilities and experimental values demonstrates the applicability of the multivariate regression approach to the prediction of migration behaviour in capillary electrophoresis on the basis of small-number measurements. The results confirm also that the separation mechanism for metal complexes is based on the differential electrophoretic migration governed by differences in charge-to-size parameters.