Comparison of enantioseparations using Cu(II) complexes with l-amino acid amides as chiral selectors or chiral stationary phases by capillary electrophoresis, capillary electrochromatography and micro liquid chromatography

In this paper we report that Cu(II) complexes with l-amino acid amides were used as chiral selectors for enantioseparation by capillary electrophoresis, capillary electrochromatography (CEC) and micro liquid chromatography using chemically modified monolithic columns. The enantioselectivity, enantiomer migration order, and the performance have been compared when different chiral selectors were used in these modes. l-Enantiomers showed longer retention times than d-forms in both CEC and LC modes. However, it has interestingly been observed that the migration order of Dns-dl-Ser showed an exception in CEC using l-prolinamide-modified column that Dns-l-Ser was eluted as the first peak. On the basis of proposed structures of complexes in the chiral recognition, differences in migration orders and recognition mechanism were discussed.