Differentiation of AB-FUBINACA and its five positional isomers using liquid chromatography-electrospray ionization-linear ion trap mass spectrometry and triple quadrupole mass spectrometry

Takaya Murakami; Yoshiaki Iwamuro; Reiko Ishimaru; Satoshi Chinaka; Nariaki Takayama; Hiroshi Hasegawa

doi:10.1007/s11419-018-0410-4

Differentiation of AB-FUBINACA and its five positional isomers using liquid chromatography-electrospray ionization-linear ion trap mass spectrometry and triple quadrupole mass spectrometry

Forensic Toxicol. 2018;36(2):351-358. doi: 10.1007/s11419-018-0410-4. Epub 2018 Mar 2.

Authors

Takaya Murakami^{1

2}, Yoshiaki Iwamuro¹, Reiko Ishimaru¹, Satoshi Chinaka¹, Nariaki Takayama¹, Hiroshi Hasegawa²

Affiliations

¹ 1Forensic Science Laboratory, Ishikawa Prefectural Police H.Q., 1-1 Kuratsuki, Kanazawa, Ishikawa 920-8553 Japan.
² 2Institute of Science and Engineering, Kanazawa University, Kakuma, Kanazawa, Ishikawa 920-1192 Japan.

Abstract

Purpose: Positional isomer differentiation is crucial for forensic analysis. The aim of this study was to differentiate AB-FUBINACA positional isomers using liquid chromatography (LC)-electrospray ionization (ESI)-linear ion trap mass spectrometry (LIT-MS) and LC-ESI-triple quadrupole mass spectrometry (QqQ-MS).

Methods: AB-FUBINACA, its two fluorine positional isomers on the phenyl ring, and three methyl positional isomers in the carboxamide side chain were analyzed by LC-ESI-LIT-MS and LC-ESI-QqQ-MS.

Results: Four of the positional isomers, excluding AB-FUBINACA and its 3-fluorobenzyl isomer, were chromatographically separated on an ODS column in isocratic mode. ESI-LIT-MS could discriminate only three isomers, i.e., the 2-fluorobenzyl isomer, the N-(1-amino-2-methyl-1-oxobutan-2-yl) isomer, and the N-(1-amino-1-oxobutan-2-yl)-N-methyl isomer, based on their characteristic product ions observed at the MS³ stage in negative mode. ESI-QqQ-MS differentiated all six isomers in terms of the relative abundances of the product ions that contained the isomeric moieties involved in collision-induced dissociation reactions. The six isomers were more clearly and significantly differentiated upon comparison of the logarithmic values of the product ion abundance ratios as a function of collision energy.

Conclusions: The present LC-MS methodologies were useful for the differentiation of a series of AB-FUBINACA positional isomers.

Keywords: AB-FUBINACA; Electrospray ionization; Linear ion trap mass spectrometry; Liquid chromatography; Positional isomer differentiation; Triple quadrupole mass spectrometry.