Direct chiral separation of amino acids derivatized with 2-(9-anthryl)ethyl chloroformate by capillary electrophoresis using cyclodextrins as chiral selectors - Effect of organic modifiers on resolution and enantiomeric elution order

Direct chiral separation of amino acids derivatized by 2-(9-anthryl)ethyl chloroformate (AEOC) has been performed by capillary electrophoresis in capillary zone electrophoretic (CZE) mode and micellar electrokinetic (MEKC) mode using cyclodextrins (CDs) as chiral selectors. The concentrations of chiral selector, surfactant and organic modifier were optimized. Application of beta- and gamma-CD as chiral selectors in MEKC, resulted in D/L separation of 12 and 13 amino acids, respectively. In CZE, chiral separation was obtained only with gamma-CD, 8 amino acids were chirally separated in this mode. Separation in the MEKC mode resulted in higher resolutions of the enantiomers than in the CZE mode. Addition of 2-propanol to the buffer caused reversal of the enantiomeric elution order for some amino acids in MEKC mode.