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Studies on the Formation of N-Methylperfluoroalkylnitrile Cations from Perfluoroacylphenethylamines in Electron Ionisation Mass Spectrometry: Unique Marker Ion Fragments in Methamphetamine Analysis

NCJ Number
European Journal of Mass Spectrometry Volume: 18 Issue: 3 Dated: July 2012 Pages: 287-299
Date Published
July 2012
13 pages

This paper reports on research and analysis regarding the formation of unique marker ion fragments in methamphetamine which is generated through the rearrangement of the perfluoroacyl immonium fragment; it discusses the research study's analysis of the scope and limitations of the rearrangement pathway; the paper provides details of the research methodology and findings.


The mass spectra of the perfluoroacyl derivatives of methamphetamine show a unique and characteristic fragment ion identified as the N-methylperfluoroalkylnitrile cation (CnF2n+1CNCH3)+. 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 Abstract Provided)

Date Published: July 1, 2012