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GC-MS and GC-IRD Studies on Dimethoxyamphetamines (DMA): Regioisomers Related to 2,5-DMA

NCJ Number
255298
Journal
Forensic Science International Volume: 192 Issue: 1-3 Dated: November 2009 Pages: 115-125
Author(s)
Hadir. M. Maher; Tamer Awad; Jack DeRuiter; C. R. Clark
Date Published
November 2009
Length
11 pages
Annotation
This article reports on GC-MS and GC-IRD studies on dimethoxyamphetamines (DMA).
Abstract
The mass spectrum of the drug of abuse 2,5-dimethoxyamphetamine (2,5-DMA) is characterized by an imine fragment base peak at m/z 44 and additional fragments at m/z 151/152 for the dimethoxybenzyl cation and radical cation, respectively. Five positional ring isomers of dimethoxyamphetamines (DMA) have an isomeric relationship to 2,5-DMA. All six compounds have the same molecular weight and produce similar EI mass spectra. This lack of mass spectral specificity for the isomers in addition to the possibility of chromatographic coelution could result in misidentification. The lack of reference materials for the potential imposter molecules constitutes a significant analytical challenge. Perfluoroacylation of the amine group reduced the nitrogen basicity and provided individual fragmentation pathways for discrimination between these compounds based on some unique fragment ions and the relative abundance of common ions. GC-IRD studies provided additional structure-IR spectra relationships and yielded confirmation level identification for each of the six regioisomeric dimethoxyamphetamines. The amines and their perfluoroacylated derivatives were resolved by capillary gas chromatography and the amines showed excellent resolution on the more polar stationary phase, Rtx-200. (publisher abstract modified)