Chiral resolution of dansyl amino acids by ligand exchange-capillary electrophoresis using Cu (II)-L-prolinamides as chiral selector

This work reports that Cu(II) complexes with L-prolinamide were used as chiral additives for the enantioseparations of dansyl amino acids by ligand exchangecapillary electrophoresis. Cu(II) complexes with L-prolinamides are present in the different forms with the change of pH, and responsible for chiral recognition with different enantioselectivity. The change of species distribution of complexes with the change of pH values was observed by visible spectrometry. The maximal wavelengths of visible absorbance curves of Cu(II)-L-prolinamide complexes gradually shift toward short wavelength with the increase of pH. D-enantiomers migrate faster than L-forms. Sodium dodecyl sulfate does not result in the reversal of enantiomer migration orders of dansyl amino acids, but improve the selectivity between analytes in this system.