High-resolution mass spectrometry and accurate mass measurement by liquid chromatography/quadrupole-time of flight mass spectrometry (LC/Q-TOFMS) was applied to postmortem plasma and urine specimens from an autopsy of a fatal case involving synthetic cannabinoid use, resulting in the detection of three synthetic cannabinoids: MAM-2201, AM-1220, and AM-2232. We searched for their metabolites existing in postmortem plasma or urine by LC/Q-TOFMS and were able to detect N-dealkylated metabolites, defluorinated and further oxidized metabolites of MAM-2201, and some hydroxylated metabolites. Postmortem plasma concentrations of the parent drugs, N-dealkylated metabolites, and fluorinated and further oxidized metabolites of MAM-2201 were measured, and quantitation results revealed site differences between heart and femoral postmortem plasma concentrations of parent drugs and some metabolites, suggesting postmortem redistribution of the synthetic cannabinoids and their metabolites. Quantitation results suggest that defluorination is a major metabolic pathway for MAM-2201, and N-dealkylation is a common but minor pathway for the naphthoylindole-type synthetic cannabinoids in human.
Keywords: LC/Q-TOFMS; Metabolism; Potential postmortem redistribution; Synthetic cannabinoid.