Potential and limitations of an optically active crown ether for chiral separation in capillary zone electrophoresis.

Capillary zone electrophoresis using optically active 18-crown-6 tetracarboxylic acid (18C6H4) as chiral selector was studied for the enantiomeric separation of primary amines. From the separation of a variety of pharmaceutical drug substances, amino alcohols and amino acids, conclusions could be made concerning the influence of the chemical structure of the analytes on the separation. In addition, the effects of experimental parameters such as pH, proportion of organic modifier and buffer composition on the separation are discussed. A synergistic effect obtained by the joint application of 18C6H4 and a cyclodextrin was exploited to resolve analytes which were separated neither by the crown ether nor by the cyclodextrin.