Determination of ephedrine compounds in nutritional supplements by cyclodextrin-modified capillary electrophoresis.

Capillary electrophoresis was utilized for the separation, identification, and quantitation of ten stereoisomers in the ephedrine family. Chiral discrimination was accomplished through the use of hydroxypropyl-beta-cyclodextrin, and separation was enhanced at pH 2 in the presence of tetramethylammonium chloride and sodium dodecyl sulfate. Calibration plots of the ephedrines were linear over the range 4-100 micrograms/ml. This method was used in the analysis of nutritional supplements that contain Ma Huang, a Chinese herbal preparation that is made from plants in the genus Ephedra.