22 巻 (2017) 2 号 p. 133-143
We present herein a practical methodology for elucidating the o-, m-, or p-fluorine substitution pattern of indazole-type synthetic cannabinoids containing a fluorobenzyl group at the N-1 position and a carbonyl group at the C-3 position via electron ionization-triple quadrupole mass spectrometry. We synthesized, as model compounds of the synthetic cannabinoids, the o-, m-, and p-fluorine positional isomers: 1-[1-(2-, 3-, and 4-fluorobenzyl)-1H-indazol-3-yl]ethanone (o-, m-, and p-FUBINAE). Mass spectral analyses showed that the three isomers differed significantly in the logarithmic values of the abundance ratios of the product ion at m/z 109 to the precursor ion at m/z 253 (ln(A109/A253)), following the order of meta<ortho<para. In addition, the relationships between ln(A109/A253) and collision energy were linear with high correlation coefficients. Comparing the ln(A109/A253) plots of the FUBINAE isomers versus collision energy with similar plots of AB-FUBINACA and its o- and m-fluorobenzyl isomers showed that the three AB-FUBINACA isomers behaved as the FUBINAE isomers did with the same fluorine substitution pattern on the phenyl ring. Moreover, other synthetic cannabinoids with a p-fluorobenzyl group (ADB-FUBINACA, FUB-AMB, FUB-APINACA, FUB-NPB-22, and FU-PX-2) also exhibited behavior similar to p-FUBINAE. These results indicated that the fluorine substitution position on the phenyl ring can be differentiated by collating the model compounds according to the logarithmic plots of their mass spectral abundance ratios as a function of the collision energy.