Separation of enantiomers in microemulsion electrokinetic chromatography using chiral alcohols as cosurfactants

Zhi Xia Zheng, Jin Ming Lin, Wing Hong CHAN, Albert W M LEE, Carmen W K HUIE*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

39 Citations (Scopus)

Abstract

A novel chiral microemulsion, which involved the use of chiral alcohols as cosurfactants, was demonstrated for the enantiomeric separation of a number of pharmaceutical drugs in microemulsion electrokinetic chromatography (MEEKC). The chiral alcohols investigated were optically active 2-alkanols, with the alkyl chain length having carbon number ranging from 4 to 7. The data indicated that, except for R-(-)-2-butanol, the use of R-(-)-2-pentanol, R-(-)-2-hexanol or R-(-)-2-heptanol as the chiral cosurfactant resulted in the baseline or partial resolution of most of the test solutes, i.e., (± -norephedrine, (±)-ephedrine, DL-nadolol, and DL-propranolol. In addition to the chain length of the chiral 2-alkanols, the effects of other experimental conditions, such as the concentration and chirality of the 2-alkanols, as well as the pH of the run buffer and the oil phase of the microemulsion, on the enantiomeric separation of the test solutes were also investigated. An interesting finding was that the water-immiscible organic solvent (oil core) within the microemulsion droplets appeared to play an important role in the chiral separation mechanism. Also, the importance of hydrogen bonding between the test solutes ((±)-ephedrine and related compounds) and the chiral microemulsion was demonstrated, as it was not possible to resolve a pair of enantiomers which lacked a β-amino proton (i.e., (± -N-methyl ephedrine) under optimized run buffer conditions (e.g., 5.0% R-(-)-2-hexanol, 0.8% n-octane, and 3.5% SDS in 90.7% borate buffer at pH 9.2).

Original languageEnglish
Pages (from-to)3263-3269
Number of pages7
JournalElectrophoresis
Volume25
Issue number18-19
DOIs
Publication statusPublished - Oct 2004

Scopus Subject Areas

  • Analytical Chemistry
  • Biochemistry
  • Clinical Biochemistry

User-Defined Keywords

  • Chiral alcohols
  • Chiral separation
  • Cosurfactant
  • Enantiomer
  • Microemulsion electrokinetic chromatography

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