Enantioseparation of alpha-amino acids and dipeptides by ligand-exchange capillary electrophoresis of various L-4-hydroxyproline derivatives

The principle of ligand exchange has been applied to the enantioseparation of underivatized aromatic and aliphatic amino acids as well as dipeptides. Two non commercially available N-alkyl-L-4-hydroxyproline derivatives were compared to underivatized L-4-hydroxyproline for their ability to resolve c r-amino acids and dipeptides. N-(2-hydroxyoctyl)-L-4-hydroxyproline and N-( 2-hydroxypropyl)-L-4-hydroxyproline were used as their copper(II) complexes as chiral selectors. With these selectors, several aliphatic amino acids a nd dipeptides, in addition to aromatic amino acids, were resolved. The pH o ptimum was found to be 4.3 for amino acids and 6.0 for dipeptides. (C) 1999 Elsevier Science B.V. All rights reserved.