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

• NCJ Number: 308936
• Journal: European Journal of Mass Spectrometry Volume: 18 Issue: 3 Dated: July 2012 Pages: 287-299
• Author(s): Tamer Awad; Hadir M. Maher; Jack DeRuiter; C. Randall Clark
• Date Published: July 2012
• Length: 13 pages
• Grant Number(s): 2006-DN-BX-K016
• Agencies: NIJ-Sponsored
• Publication Type: Research (Applied/Empirical)

Annotation

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.

Abstract

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)