Strategies for selectivity control in capillary electrophoresis of metal species

Capillary electrophoresis has recently attracted considerable attention as a promising analytical technique for metal ion separations. Significant advances that open new application areas for capillary electrophoresis in the analysis of metal species have occurred based on exploiting various auxiliary separation principles. These are mainly due to complexation, ion pairing, solvation and micellization interactions between metal analytes and electrolyte additives which alter the separation selectivity in a broad range. Likewise, many separation studies for metal ions have been concentrated on the use of pre-electrophoresis derivatisation methodology. Approaches suitable for manipulation of selectivity for different metal species including metal cations, metal complexes, metal oxoanions and organometallic compounds, are discussed, with special attention paid to the related electrophoretic system variables using illustrative examples. Discussion also presents guidelines for optimisation of separation conditions based on basic theoretical considerations. (C) 1997 Elsevier Science B.V.