Comparison of enantioseparation of amino acid derivatives in aqueous and mixed aqueous-organic media by capillary zone electrophoresis

The chiral separation of dansyl-amino acids has been performed by capillary zone electrophoresis using beta-cyclodextrin as a chiral selector, urea as an additive and 2-propanol and methanol as organic modifiers. The enantiomeric separations of dansyl-amino acids were investigated in aqueous medium and compared with the separation in mixed aqueous-organic medium as background electrolytes. The separation conditions, (concentration of buffer, beta-cyclodextrin, methanol, urea and the pH value of buffer) were optimized. In the absence of organic modifier, only five pairs of 8 separated dansyl-amino acids were resolved when run separately. A mixture of up to eight chiral amino acids can be baseline resolved in less than 19 min by beta-cyclodextrin-modified capillary zone electrophoresis with a buffer of 60 mmol L-1 H3BO3-KCl/40 mmol L-1 NaOH (pH 9.0), 4 mol L-1 urea, 100 mmol L-1 beta-cyclodextrin and 10% (v/v) methanol.