title: Electron ionization mass spectra of ephedrines in a doping confirmatory procedure: a curious migration of the trimethylsilyl group in the N-acetyl-O-trimethylsilyl derivatives.
abstract: Ephedrines have central nervous system stimulating properties and, for this reason, some of them are forbidden in sport by the World Antidoping Agency (WADA). They are screened and quantitated in urine by several published techniques and confirmed by gas chromatography/mass spectrometry (GC/MS). In this paper, a simple confirmation procedure for norpseudoephedrine, norephedrine, ephedrine and pseudoephedrine in human urine by GC/electron ionization (EI)-MS is described. After the addition of levallorphane as internal standard, a liquid-liquid extraction procedure under alkaline conditions with tert-butyl methyl ether was applied to the samples. The analytes were derivatized with acetic acid anhydride and N-methyl-N-trimethylsilyltrifluoroacetamide to form N-acetyl-O-trimethylsilyl derivatives. The EI mass spectra of all the studied substances have many diagnostic ions with relative abundance in accordance with WADA requirements and show great structural information content. A curious migration of the trimethylsilyl group is proposed.
authors.affiliation: Instituto de Medicina del Deporte, Laboratorio Antidoping, Calle 100 y Aldabó, CP 10800, Ciudad de la Habana, Cuba. rodnylad@yahoo.com
authors.forename: Rodny Montes
authors.initials: RM
authors.lastname: de Oca Porto
authors.forename: Arístides Rosado
authors.initials: AR
authors.lastname: Pérez
authors.forename: Margarita Teresa
authors.initials: MT
authors.lastname: Correa Vidal
mesh_terms: D000697:Central Nervous System Stimulants / Q000737:chemistry / Q000652:urine; D004300:Doping in Sports / Q000379:methods*; D004809:Ephedrine / Q000031:analogs & derivatives / Q000737:chemistry / Q000652:urine; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006801:Humans; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D014297:Trimethylsilyl Compounds / Q000737:chemistry*
chemical_list: D000697:Central Nervous System Stimulants; D014297:Trimethylsilyl Compounds; D004809:Ephedrine