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

Authors:
Publisher website
Google Scholar
Abstract
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 ∼48 finished products. Keywords: Ephedra; ephedrine alkaloids; synephrine; dietary supplements; cation exchange; HPLC; analysis; determination; UV spectra; fluorescence

This publication has 7 references indexed in Scilit: