METAL-ION CAPILLARY ELECTROPHORESIS WITH DIRECT UV DETECTION EFFECT OF A CHARGED SURFACTANT ON THE MIGRATION BEHAVIOR OF METAL-CHELATES

The migration behaviour of anionic metal 4-(2-pyridylazo)resorcinol (P AR) and Arsenate III complexes was investigated in capillary electroph oresis (CE) using micellar solutions of sodium dodecyl sulphate. The s eparation mechanism of arsenate complexes is governed by the electroph oresis in the bulk carrier electrolyte without any observable interact ion with the micellar phase. For less hydrophilic PAR complexes, the r esolution can be additionally explained in terms of differential parti tioning into the micelle. It was also found that ion-pair formation be tween anionic solutes and the cationic component of the electrophoreti c buffer contributes to the retention mechanism and permits the separa tion of closely migrating PAR complexes. Both chelating systems have b een applied to the CE separation and determination of various metal io ns with enhanced selectivity and sensitivity relative to previously re ported metal complexation CE techniques. Application to the analysis o f complex sample matrices, containing high levels of acids and complex ing agents, was demonstrated.