Enantiomeric separation and quantification of ephedrine-type alkaloids in herbal materials by comprehensive two-dimensional gas chromatography

Min Wang, Philip J. Marriott, Wing Hong CHAN, Albert W M LEE, Carmen W K HUIE*

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

47 Citations (Scopus)


The separation of ephedrine-type alkaloids and their enantiomers in raw herbs and commercial herbal products was investigated by carrying out enantioselective separation in the first-dimension column (containing β-cyclodextrin as the chiral selector) of a comprehensive two-dimensional gas chromatography (GC × GC) system, whereas a polar polyethylene glycol capillary column was used for separation in the second dimension. Naturally occurring ephedrine-type alkaloids and their synthetic analogues (enantiomeric counterparts) were adequately resolved from each other, as well as from potential interference species in the sample matrix using GC × GC, whereas single column GC analysis was unable to separate all the alkaloids of interest. Detection limits in the order of 0.1-1.3 μg/mL and linearity of calibration with R2 ≥ 0.999 over approximately the range of 0.5-100 μg/mL for the quantitative determination of various ephedrine-type alkaloids were obtained. The commercial herbal products tested contained mostly (-)-ephedrine, (+)-pseudoephedrine, (-)-N-methylephedrine and (-)-norephedrine, with concentrations in the range of 40-2100, 0-1300, 15-300 and 0-30 μg/g of the product, respectively, and repeatability of analysis was generally in the range of 1-5%. The present GC × GC method is effective and useful for the determination of the dosage levels of the principle ephedrine-type alkaloids in commercial health supplements and complex raw herb formulations, as well the differentiation of ephedrine-containing products that were derived from natural plant or synthetic sources, e.g., simply by visualizing the presence or absence of the enantiomeric pairs of (±) ephedrine and (±)-N-methylephedrine in the GC × GC chromatograms.

Original languageEnglish
Pages (from-to)361-368
Number of pages8
JournalJournal of Chromatography A
Issue number1-2
Publication statusPublished - 21 Apr 2006

Scopus Subject Areas

  • Analytical Chemistry
  • Biochemistry
  • Organic Chemistry

User-Defined Keywords

  • Chiral separation
  • Comprehensive two-dimensional gas chromatography
  • Ephedrine alkaloids
  • Herbs


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