Abstract
GC separation of the methylenedioxybenzyl analogues of the 25X-NBOMe drugs.
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•The analytical properties of ten 25X-NBOMe analogues are described.•The isomeric molecules have a methylenedioxybenzyl ring substitution pattern.•Capillary GC yields excellent resolution of these compounds.•EI-MS yields fragment ions characteristic of substituted phenethylamines.•EI-MS fragmentation mechanisms are described.
In this study, the oxygenated benzyl aromatic ring of the classic NBOMe drugs such as 25B-NBOMe and 25I-NBOMe (with N-methoxybenzyl) were modified to contain the 2,3- and 3,4-methylenedioxy group in both phenethylamine and phenylisopropylamine molecular scaffolds. The aromatic ring of the phenethylamine core structural skeleton was held constant as the 2,5-dimethoxy substitution pattern with the 4-position group varied yielding the 4-bromo (25B), the 4-iodo (25I) as well as the 25H unsubstituted subsets. The 25H and 25B subsets for the phenylisopropylamine skeleton were also included and the resulting ten compounds were evaluated in GC–MS studies. The ten compounds were baseline resolved using a 30 m column containing a silarylene film phase (Rxi®-17Sil MS) eluting over a period of about eleven minutes. The 2,3-methylenedioxybenzyl substituted isomer eluted before the corresponding 3,4-methylenedioxybenzyl substituted regioisomer for each subset and the branched chain phenylisopropylamine analogues eluted before the phenethylamines having identical aromatic ring substituents.
Initial ionization at the amine nitrogen followed by iminium cation formation (m/z 164 or m/z 178) via loss of the various substituted (H, Br, or I)-2,5-dimethoxybenzyl radicals allows the phenethylamines to be distinguished from the phenylisopropylamine analogues. The m/z 135 ion can form directly from the molecular radical cation and as the product ion of the iminium cation. A series of less prominent high mass ions in the halogenated dimethoxyphenyl substituted compounds occur via a common pathway yielding the halogenated dimethoxybenzyl cation and radical cation.