Differentiation of FUB-JWH-018 positional isomers by electrospray ionization–triple quadrupole mass spectrometry

Abstract

Analytical differentiation of the positional isomers of synthetic cannabinoids (SCs) is a notable issue in forensic drug analysis, because only one or two of the imaginable isomers are controlled legally in most cases. Two series of fluorine-substituted SCs, differing in the substituent positions, were examined by electrospray ionization–triple quadrupole mass spectrometry (ESI-QqQ MS) to assess the capabilities of this technique to differentiate their positional isomers. The mass spectra of (1-(4-fluorobenzyl)-1H-indol-3-yl)(naphthalen-1-yl)methanone (FUB-JWH-018) and its positional isomers were recorded while the collision energy was varied (5–90 eV), and the fragment ions of the protonated precursor ions [M+H]+ were characterized. The applicability of ESI-QqQ MS in the positive mode was demonstrated by analyzing the naphthalen-2-yl derivative of FUB-JWH-018 and its positional isomers. The statistical analysis of the principal fragment ions in the 80 eV spectra of each synthetic cannabinoid allowed the authors to significantly differentiate its isomers based on their m/z (127:109) ratio.