title: Studies on the formation of N-methylperfluoroalkylnitrile cations from perfluoroacylphenethylamines in electron ionisation mass spectrometry: unique marker ion fragments in methamphetamine analysis.
abstract: The mass spectra of the perfluoroacyl derivatives of methamphetamine show a unique and characteristic fragment ion identified as the N-methylperfluoroalkylnitrile cation (C(n)F(2n+1)CNCH(3))(+). This ion appears at various m/z values depending on the nature of the perfluoroacyl species and is generated via rearrangement of the perfluoroacyl immonium fragment formed by loss of the benzyl-radical from the molecular ion. Analogous ions have been described in the mass spectra of other methamphetamine-like side chain substances regardless of the aromatic ring substitution pattern. The scope and limitation of this rearrangement pathway were evaluated in this study by preparing a set of substituted phenethylamines and related compounds of varying structure. The perfluoroacyl moiety leads to the formation of the highest abundance of the N-methyl nitrile cation fragment while hydrocarbon acyl groups do not show the N-methylnitrile cation as a significant peak. The N-methyl group is required for the formation of the N-methyl nitrile cation and higher N-alkyl homologues eliminate the corresponding alkene species from the acyl immonium fragment. The loss of benzaldehyde and acetone from the perfluoroacylimmonium species produces the highest relative abundance of the unique N- methylperfluoroalkylnitrile cation.
authors: Department of Pharmacal Sciences, Harrison School of Pharmacy, Auburn University, AL 36849, USA.
authors: Tamer
authors: T
authors: Awad
authors: Hadir M
authors: HM
authors: Maher
authors: Jack
authors: J
authors: DeRuiter
authors: C Randall
authors: CR
authors: Clark
mesh_terms: D000215:Acylation; D002412:Cations / Q000032:analysis / Q000737:chemistry*; D004583:Electrons; D053593:Forensic Toxicology / Q000295:instrumentation / Q000379:methods*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006801:Humans; D006845:Hydrocarbons, Fluorinated / Q000032:analysis / Q000737:chemistry; D008694:Methamphetamine / Q000032:analysis / Q000737:chemistry*; D009570:Nitriles / Q000032:analysis / Q000737:chemistry; D015813:Substance Abuse Detection / Q000295:instrumentation / Q000379:methods*
chemical_list: D002412:Cations; D006845:Hydrocarbons, Fluorinated; D009570:Nitriles; D008694:Methamphetamine