Stacking and separation of enantiomers by acetonitrile-salt mixtures in micellar electrokinetic chromatography

Tom M.H. Choy, Wing Hong CHAN, Albert W M LEE, Carmen W K HUIE*

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

25 Citations (Scopus)


The feasibility of employing the "acetonitrile stacking" method in micellar electrokinetic chromatography (MEKC) for the on-line preconcentration and separation of enantiomers is demonstrated for the first time. The effects of various experimental parameters on the stacking and separation of three different pairs of optical isomers, i.e., two substituted naphthyl enantiomers and one dansylated-DL-amino acid, were examined. In particular, the effectiveness of the addition of acetonitrile and salt in the sample matrix to induce narrowing of the analyte bands was investigated in the presence of sodium cholate as the chiral surfactant micelle in the separation buffer. For example, it was found that the presence of both acetonitrile and 1% NaCl in the sample matrix (volume ratio = 2:1) led to a significant improvement of the peak height and resolution for the MEKC separation of a pair of R(-)/S(+)-1,1′-binaphthyl diyl hydrogen phosphate enantiomers when the injection sample size was relatively large (e.g., 12% capillary volume). Furthermore, the feasibility of combining salting-out solvent extraction (off-line) and acetonitrile stacking (on-line) as a novel approach for sample preconcentration in capillary electrophoresis was also demonstrated.

Original languageEnglish
Pages (from-to)3116-3123
Number of pages8
Issue number18
Publication statusPublished - Sept 2003

Scopus Subject Areas

  • Analytical Chemistry
  • Biochemistry
  • Clinical Biochemistry

User-Defined Keywords

  • Acetonitrile-salt mixtures
  • Enantiomers
  • Micellar electrokinetic chromatography
  • Stacking


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