title: β-Methylphenylethylamines: common fragmentation pathways with amphetamines in electrospray ionization collision-induced dissociation.
abstract: β-Methylphenylethylamines are positional isomers of amphetamines and have been discovered in sporting supplements. Although the fragmentation of the β-methylphenylethylamine and N-methyl-β-methylphenylethylamine in gas chromatography-electron ionization-mass spectrometry (GC-EI-MS) systems is significantly different to their amphetamine and methylamphetamine isomers, under electrospray ionization commonly used in liquid chromatography-mass spectrometry (LC-MS) systems, the fragmentation of each of the isomeric pairs is almost identical. The similarities in fragmentation make it possible for the misidentification of the β-methylphenylethylamines as the illicit amphetamines. It is proposed that the similarities are due to a fragmentation pathway involving a common phenonium ion intermediate. By careful control of fragmentation energies in liquid chromatography-tandem mass spectrometry (LC-MS/MS) systems and/or close examination of the relative abundances of product ions formed by collision-induced dissociation (qualifier ratios), it is possible to distinguish the β-methylphenylethylamines from the amphetamines, even if significant retention time separation is not achieved. In liquid chromatography-electrospray ionization-quadrupole time of flight (LC-ESI-QTOF) systems the mass spectra of the β-methylphenylethylamines are identical to their amphetamine isomers. In such systems, retention time separation of the isomers is critical to avoid misidentification. During this study β-methylphenylethylamine and N-methyl-β-methylphenylethylamine have been identified in commercially available sporting supplements and oral fluid samples taken during the course of road-side drugs-in-drivers and workplace testing programmes. Copyright © 2015 John Wiley & Sons, Ltd.
authors.affiliation: Forensic Toxicology Section, Forensic Science Laboratory, ChemCentre, Western Australia.|Department of Chemistry, Curtin University, GPO Box U1987, Perth, WA 6845, Australia.
authors.forename: David H
authors.initials: DH
authors.lastname: Brown
authors.affiliation: Forensic Toxicology Section, Forensic Science Laboratory, ChemCentre, Western Australia.
authors.forename: Robert
authors.initials: R
authors.lastname: Hansson
authors.affiliation: Forensic Toxicology Section, Forensic Science Laboratory, ChemCentre, Western Australia.
authors.forename: Francois
authors.initials: F
authors.lastname: Oosthuizen
authors.affiliation: Forensic Toxicology Section, Forensic Science Laboratory, ChemCentre, Western Australia.
authors.forename: Nathan
authors.initials: N
authors.lastname: Sumner
mesh_terms: D000662:Amphetamines / Q000032:analysis* / Q000737:chemistry; D002849:Chromatography, Gas / Q000379:methods; D002853:Chromatography, Liquid / Q000379:methods*; D019587:Dietary Supplements / Q000032:analysis*; D007536:Isomerism; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D015813:Substance Abuse Detection / Q000379:methods; D053719:Tandem Mass Spectrometry / Q000379:methods
chemical_list: D000662:Amphetamines; C000600517:beta-methylphenyl-ethylamine
keywords: amphetamines; beta-methylphenylethylamines; sporting supplements; stimulants