Determination of ephedrine alkaloids and synephrine in dietary supplements by column-switching cation exchange high-performance liquid chromatography with scanning-wavelength ultraviolet and fluorescence detection.
An HPLC method with on-line cleanup coupled to the separation column is described for determination of (-)-norephedrine, (+)-norpseudoephedrine, (-)-ephedrine, (+)-pseudoephedrine, (-)-N-methylephedrine, (+)-N-methylpseudoephedrine, and (+/-)-synephrine in finished dietary supplement products. Test portions were extracted in acidified aqueous acetone. A filtered aliquot was cleaned up on a strong cation exchange (SCX) precolumn that later was automatically coupled to the SCX analytical column. Measurement was by full-scan UV spectra for confirmation of identity by spectral matching and real-time integration of three wavelength signals for multiple quantitation. (+/-)-Synephrine was also quantitated by native fluorescence. Recovery averaged 95-100%. Determination of the major ingredients (-)-ephedrine, (+)-pseudoephedrine, and (+/-)-synephrine compared favorably to findings by an independent LC-MS analysis for a set of 25 samples. The results of a survey were reported for total ephedrine alkaloid and synephrine content and were compared to content declaration, for approximately 48 finished products.
Niemann
Richard A
RA
Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, 5100 Paint Branch Parkway, College Park, MD 20740, USA. rniemann@cfsan.fda.gov
Gay
Martha L
ML
D000470:Alkaloids / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D019587:Dietary Supplements / Q000032:analysis*; D004809:Ephedrine / Q000032:analysis*; D005453:Fluorescence; D013056:Spectrophotometry, Ultraviolet; D013578:Synephrine / Q000032:analysis*
D000470:Alkaloids; D004809:Ephedrine; D013578:Synephrine