The differentiation of 2,5-dimethoxy-N-(N-methoxybenzyl)phenethylamine (NBOMe) isomers using GC retention indices and multivariate analysis of ion abundances in electron ionization mass spectra
Forensic Chemistry June 1, 2019 J. T. Davidson, Glen P. Jackson
Positional isomers of the synthetic phenethylamine derivatives 25C-NBOMe and 25I-NBOMe can be reliably distinguished using retention indices and fragment ion abundances measured by gas chromatography–mass spectrometry. Retention indices for the six isomers on three different 5% diphenyl columns ranged from 2614 to 2904, with 95% confidence intervals of 12–16. Chemometric methods—principal component analysis and canonical discriminant analysis—achieved 99.5% classification accuracy across three instrumental setups and a wide concentration range, and greater than 99.9% accuracy within a single instrument when low-abundance spectra were excluded. These findings support the use of retention indices and chemometric classification for identifying unknown NBOMe isomers, aiding forensic and regulatory efforts.