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GC-MS Analysis of Regioisomeric Substituted N-Benzyl-4-Bromo-2,5-Dimethoxyphenethylamines

NCJ Number
Forensic Chemistry Volume: 14 Dated: June 2019
Date Published
June 2019
10 pages

This study describes six N-(dimethoxybenzyl)-4-bromo-2,5-dimethoxyphenethylamine regioisomers, which are potential designer compounds related to the common NBOMe drug N-(2-methoxy)benzyl-4-bromo-2,5-dimethoxyphenethylamine (25B-NBOMe).


These six compounds represent the incorporation of one additional methoxy-group into the common NBOMe molecular framework. The compounds were prepared from commercially available precursor materials and their electron ionization mass spectra (EI-MS) are quite similar yielding nearly identical fragment ions. The 2,3-dimethoxybenzyl regioisomer gave a unique fragment ion of significant abundance in the EI-MS at m/z 136. Baseline gas chromatographic resolution of the six regioisomers was achieved using a midpolarity phase of 50 percent phenyl and 50 percent dimethyl polysiloxane and the more crowded dimethoxy substitution patterns eluted first under temperature programming conditions. The EI mass spectra for the TFA-derivatives of these six regioisomers gave a molecular ion of significant abundance at m/z 505/507, unlike the parent compounds. Differentiation and specific identification of all six of the regioisomers was possible based on a combination of different base peak ions (m/z 151 or 242/244), unique fragment ions (m/z 136 and m/z 263), and differences in the relative abundance of ions at m/z 121 and m/z 91. (publisher abstract modified)

Date Published: June 1, 2019