A general approach to the screening and confirmation of tryptamines and phenethylamines by mass spectral fragmentation.

Mass spectrometry methods—GC-EI/MS, LC-ESI/MS, and MALDI/TOFMS—were compared for analyzing 13 tryptamine and phenethylamine compounds, including AMT, DMT, 5-MeO-AMT, DET, DPT, DBT, DIPT, 5-MeO-DMT, 5-MeO-DIPT, methamphetamine, 3,4-MDA, 3,4-MDMA, and MBDB. Parent ions were difficult to obtain by GC/MS, but protonated molecular ions were clearly observed by ESI/MS and MALDI/TOFMS. Two major characteristic fragmentations occurred: alpha-cleavage (producing [3-vinylindole]+) and beta-cleavage (producing [CH2N(+)R(N1)R(N2)]). With ESI, alpha-cleavage was the major process; with MALDI, beta-cleavage dominated. The ionization efficiency and fragments from either cleavage depended on the degree of alkylation of the side chain nitrogen.

Study at a glance

Abstract

Certain characteristic fragmentations of tryptamines (indoleethylamine) and phenethylamines are described. Based on the GC-EI/MS, LC-ESI/MS and MALDI/TOFMS, the mass fragmentations of 13 standard compounds, including alpha-methyltryptamine (AMT), N,N-dimethyltryptamine (DMT), 5-methoxy-alpha-methyltryptamine (5-MeO-AMT), N,N-diethyltryptamine (DET), N,N-dipropyltryptamine (DPT), N,N-dibutyltryptamine (DBT), N,N-diisopropyltryptamine (DIPT), 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT), 5-methoxy-N,N-diisopropyltryptamine (5-MeO-DIPT), methamphetamine (MAMP), 3,4-methylenedioxyamphetamine (3,4-MDA), 3,4-methylenedioxymethamphetamine (3,4-MDMA) and 2-methylamino-1-(3,4-methylenedioxyphenyl)butane (MBDB), were compared. As a result, the parent ions of these analytes were hard to be obtained by GC/MS whereas the protonated molecular ions can be observed clearly by means of ESI/MS and MALDI/TOFMS. Furthermore, two major characteristic fragmentations, namely and alpha-cleavage ([M+H](+)-->[3-vinylindole](+)) and beta-cleavage ([M+H](+)-->[CH(2)N(+)R(N1)R(N2)]), are produced when the ESI and MALDI modes are used, respectively. In the case of ESI/MS, the fragment obtained from alpha-cleavage is the major process. In contrast to this, in the case of MALDI/TOFMS, the major fragment is produced via beta-cleavage. The ionization efficiency and fragments formed from either alpha- or beta-cleavages are closely related to the degree of alkylation of the side chain nitrogen in both cases.