Characterization of diastereomeric and enantiomeric ephedrines by gas chromatography combined with electron impact mass spectrometry and isobutane chemical ionization mass spectrometry.

Article abstract of DOI:10.1002/bms.1200040407

The diastereomeric hydroxyamines, ephedrine and psi-ephedrine, were well differentiated by gas chromatography of their N-acetyl O-trimethylsilyl derivatives. For the analytical separation of enantiomers, conversion into N-(R)-alpha-phenylbutyryl O-trimethylsilyl derivatives was effective in the cases of ephedrine, psi-ephedrine and nor-psi-ephedrine (but not that of nor-ephedrine, on the two stationary phases used). Electron impact mass spectra showed structurally diagnostic fragmentations, but the two diastereomeric amides from each pair of enantiomers yielded generally similar spectra. Molecular ions were of low abundance, but under chemical ionization conditions (isobutane) abundant protonated molecular ions were produced.