Title
Abstract
Dietary supplements containing ephedra, either alone or in combination with other ingredients, have been marketed extensively in recent years for weight reduction, increasing energy, and enhancing athletic performance. The stimulant effects of ephedra are linked to the presence of six alkaloids: (-)-ephedrine, (+)-pseudoephedrine, (-)-N-methylephedrine, (+)-N-methyl-pseudoephedrine, (-)-norephedrine, and (+)-norpseudoephedrine. Each of these six compounds also has an enantiomer that does not occur naturally in the plant. Detection of the “unnatural” enantiomers would therefore suggest that the dietary supplement content had been altered through the addition of synthetic alkaloids. Hence, the enantiomeric composition of these compounds is important in verifying the natural (plant) origin of the alkaloids. We developed three complementary capillary electrophoresis (CE) methods for the determination of ephedrine and pseudoephedrine enantiomers in dietary supplements and related materials. Results were found to be comparable to data from other measurement techniques, and only minimal sample preparation was required for CE analysis. The CE methods have been applied successfully to the value assignment of the ephedrine alkaloid content of five Standard Reference Materials (SRMs) containing ephedra.
Biographical Sketch
Karen Phinney received a B.A. in chemistry from Monmouth College. She worked as a chemist for Monsanto for several years before attending graduate school. She received her Ph.D. in chemistry from University of Hawaii-Manoa in 1994, under the direction of Apryll Stalcup. She began working at NIST as an NRC Postdoctoral Research Associate, and she is now a Research Chemist in the Analytical Chemistry Division at NIST. Her research interests include chiral separations, dietary supplements, forensic analysis, and various separation techniques, including capillary electrophoresis and supercritical fluid chromatography.