Arapid, isocratic method for the separation of 6 ephedrine-type alkaloids which may occur in dietary supplements was modified to permit quantitation and confirmation by liquid chromatography/mass spectrometry using atmospheric pressure chemical ionization. Several columns and sets of conditions were examined for suitability and the results compared. The use of ion-pairing reagents to enhance resolution is also reported. Mass spectrometric conditions were adjusted to provide sufficient fragmentation for qualitative identification of the analytes. Stable-isotope labeled ephedrine was used as an internal standard for quantitation.