Recent innovation in capillary electrokinetic chromatography with replaceable charged pseudostationary phases or additives

Recent developments of separation of neutral analytes in capillary systems with the mobile phase driven by the electroosmotic flow (EOF) and charged additives acting as a pseudostationary phase are reviewed. As pseudostationary phases a number of additives are used. Soluble polymers, either anionic or cationic, were applied as alternatives to micelles. Monomeric charged additives are also intended to form associates with the analytes, leading to selective retention and separation in a similar way as the polymeric pseudostationary phases. Dendrimers, spherical macromolecules with highly branched chains and charged terminal groups, are successfully applied for the separation of lipophilic analytes. Polymers with covalently stabilized structures are introduced in the form of permanent micelles and are therefore insensitive to the mobile phase composition, enlarging the applicability of micellar electrokinetic capillary chromatography (MEKC).