Investigation of quality in ephedrine-containing dietary supplements.

Ephedra alkaloids in 47 dietary supplements were measured to examine variability within and between products as well as for comparison of actual constituents with label claims of manufactured products. Samples were analyzed for (-)-ephedrine, (+)-pseudoephedrine, (-)-methylephedrine, (+)-methylpseudoephedrine,(-)-norephedrine, and (+)-norpseudoephedrine without derivatization using gas chromatographic mass spectrometry (GC/MS). Samples were then screened for pharmaceutically derived chiral contaminants.