351. Studies on the formation of N-methylperfluoroalkylnitrile cations from perfluoroacylphenethylamines in electron ionisation mass spectrometry: unique marker ion fragments in methamphetamine analysis.
- Author
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Awad T, Maher HM, DeRuiter J, and Clark CR
- Subjects
- Acylation, Cations analysis, Electrons, Forensic Toxicology instrumentation, Humans, Hydrocarbons, Fluorinated analysis, Hydrocarbons, Fluorinated chemistry, Methamphetamine analysis, Nitriles analysis, Nitriles chemistry, Substance Abuse Detection instrumentation, Cations chemistry, Forensic Toxicology methods, Gas Chromatography-Mass Spectrometry methods, Methamphetamine chemistry, Substance Abuse Detection methods
- 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.
- Published
- 2012
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