Fragmentation Pathways of Trifluoroacetyl Derivatives of Methamphetamine, Amphetamine, and Methylenedioxyphenylalkylamine Designer Drugs by Gas Chromatography/Mass Spectrometry

Takeshi Kumazawa,Seisaku Uchigasaki,Chika Hasegawa,Osamu Suzuki,Hiroshi Seno,Xiao-Pen Lee,Keizo Sato,Kenji Hara

doi:10.1155/2011/318148

Abstract

Methamphetamine (MA), amphetamine (AM), and the methylenedioxyphenylalkylamine designer drugs, such as 3,4‐methylenedioxymethamphetamine (MDMA), 3,4‐methylenedioxyethylamphetamine (MDEA), N‐methyl‐1‐(3,4‐methylenedioxyphenyl)‐2‐butanamine (MBDB), 3,4‐methylenedioxyamphetamine (MDA), and 3,4‐(methylenedioxyphenyl)‐2‐butanamine (BDB), are widely abused as psychedelics. In this paper, these compounds were derivatized with trifluoroacetic (TFA) anhydride and analyzed by gas chromatography/mass spectrometry using electron ionization in positive mode. Gas chromatographic separation for TFA derivatives of all compounds was successfully resolved using an Equity‐5 fused silica capillary column with a poly (5% diphenyl‐95% dimethylsiloxane) stationary phase. Base peaks or prominent peaks of MA, AM, MDMA, MDEA, MBDB, MDA, and BDB appeared at m/z 154, 140, 154, 168, 168, 135, and 135, respectively. These occurred due to α‐cleavage from the amide nitrogen, splitting into the TFA imine species and benzyl or methylenedioxybenzyl cations. Further prominent fragment ions at m/z 118 for MA and AM, m/z 162 for MDMA, MDEA, and MDA, and m/z 176 for MBDB and BDB were produced by cleavage of the phenylpropane or methylenedioxypropane hydrocarbon radical cation via a hydrogen rearrangement. These fragmentation pathways for the TFA derivatives of all the compounds are summarized and illustrated in this paper.

Highlights

Extensive attention in clinical and forensic toxicology has focused on the increasing abuse of methamphetamine (MA), amphetamine (AM), and methylenedioxyphenylalkylamine derivatives, such as 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyethylamphetamine (MDEA), N-methyl-1-(3,4-methylenedioxyphenyl) -2-butanamine (MBDB), 3,4-methylenedioxyamphetamine (MDA), and 3,4-(methylenedioxyphenyl)-2-butanamine (BDB)
We present mass spectra and detailed fragmentation pathways for MA, AM, MDMA, MDEA, MBDB, MDA, and BDB using gas chromatography (GC)/mass spectrometry (MS) in electron ionization (EI) mode after acylation derivatization
Excess TFA and byproducts such as, trifluoroacetic acid, are produced in reactions with the target compounds [24]. These have to be removed from the extract prior to the GC/MS analysis, in order to avoid damaging to the GC column [25]

Summary

Introduction

Extensive attention in clinical and forensic toxicology has focused on the increasing abuse of methamphetamine (MA), amphetamine (AM), and methylenedioxyphenylalkylamine derivatives, such as 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyethylamphetamine (MDEA), N-methyl-1-(3,4-methylenedioxyphenyl) -2-butanamine (MBDB), 3,4-methylenedioxyamphetamine (MDA), and 3,4-(methylenedioxyphenyl)-2-butanamine (BDB). Several gas chromatographic methods to analyze MA, AM, MDMA, MDEA, MBDB, MDA, and BDB in doping control and toxicological analysis have been reported [5,6,7,8]. Because of their relatively low molecular weights, high. Quantitative analysis of MA, AM, and the methylenedioxyphenylalkylamine designer drugs has been frequently performed in clinical and forensic toxicology by GC/MS-EI with derivatization [8, 12,13,14,15,16,17], systematic studies of mass spectrometric behavior for these compounds have been limited [9, 18, 19]. We present mass spectra and detailed fragmentation pathways for MA, AM, MDMA, MDEA, MBDB, MDA, and BDB using GC/MS in EI mode after acylation derivatization

Experimental Part

H5 N CF3

Results and Discussion

Conclusions