Fast enantioseparation of arylglycine amides by capillary electrophoresis with highly sulfated-β-cyclodextrin as a chiral selector

Nine racemic arylglycine amides were synthesized and successfully enantioseparated by capillary electrophoresis (CE) using highly sulfated β-cyclodextrin (HS-β-CD) as a chiral selector. Baseline enantioseparation of the analytes was obtained around neutral pH but not in the acidic conditions that are commonly used. HS-β-CD content, buffer pH, type and concentration, and organic modifier concentration were studied and optimized for fast and efficient separation. A chiral CE separation system composed of 1.5% (w/v) HS-β-CD, 0 to 10% (v/v) methanol and 20 mM 3-(N-morpholino)propanesulfonic acid at pH 6.5 was shown suitable for baseline enantioseparation of the mentioned amides within 6 min, including simultaneous enantioseparation of three positional isomer series (methyl-, methoxyl or chloro-substituted). By using this system, d-enantiomers migrated ahead of the l-enantiomers and the enantiomeric resolution order of arylglycine amides was more or less parallel to the pKa order of the analytes.