Enantioseparation of α-amino acids by means of Cinchona alkaloids as selectors in chiral ligand-exchange chromatography

S. KEUNCHKARIAN, C. FRANCA, L. GAGLIARDI, C. B. CASTELLS

JOURNAL OF CHROMATOGRAPHY - A

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2013 vol. 1298 p. 103 - 108

0021-9673

A conventional nonchiral column was used for the enantioseparation of several racemic α-amino acids (native and derivatized) through the use of Cinchona alkaloids as chiral selectors along with Cu(II)  ions  in  chiral  ligand-exchange  chromatography.  The mobile  phase  composition  (i.e.,  the organic  modifier  content  and  pH)  was  studied  in  order  to  modulate  retention  and enantioselectivity. Good enantioseparation of many amino acids was obtained using  equimolar amounts of Cu(II) and either cinchonidine, quinine or quinidine as chiral selectors  in  the mobile phase.  The  molecular  geometry  of  the  diastereomeric  complexes  formed  was  modelled  and energetic  differences  between  both  compounds  were  calculated  by  methods  based  on  semi-empirical  force-field.  Good  correlations  were  obtained  between  experimental  enantioselectivity factors and calculated energetic differences.