Identification and quantitation of 5-fluoro-ADB, one of the most dangerous synthetic cannabinoids, in the stomach contents and solid tissues of a human cadaver and in some herbal products

Since late September 2014, there have been approximately 10 cases in Japan where people have died from inhaling smoke from herbal blends containing a newly emerged synthetic cannabinoid. Although the drug was tentatively identified by some drug-monitoring institutions as 5-fluoro-ADB, to our knowledge, its data have not been published in any scientific context. We recently encountered an autopsy case in which 5-fluoro-ADB was involved. The deceased was a 34-year-old man who was found dead in his room. The postmortem interval was estimated at 35–40 h. The direct cause of the death was asphyxia due to aspiration of stomach contents into the trachea, which likely took place during vomiting under low-consciousness conditions provoked by inhalation of the 5-fluoro-ADB smoke. The cadaver was subjected to autopsy at our department. Femoral vein blood, right heart blood, left heart blood, urine, stomach contents, and nine solid tissues including the adipose tissue were collected and frozen until analysis. The extraction of 5-fluoro-ADB and internal standard 5-fluoro-AMB was performed using a modified QuEChERS method plus filtration through Captiva ND Lipids cartridges, followed by liquid chromatography–tandem mass spectrometry (LC–MS–MS) analysis. Because this study dealt with various kinds of human matrices, we used the standard addition method for quantitation to overcome the matrix effects. The levels of 5-fluoro-ADB in the cadaver specimens were generally low; it could not be detected from blood or urine specimens. The levels of 5-fluoro-ADB in solid tissues were 1.17–7.95 ng/g. Because the highest levels were found for the adipose tissue and heart muscle, the final extracts of the adipose tissue and/or heart muscle were concentrated 10- and 200-fold to obtain product ion mass spectra of 5-fluoro-ADB using LC–MS–MS and its mass spectrum by gas chromatography–mass spectrometry, respectively. Both spectra completely coincided with those obtained from the reference standard 5-fluoro-ADB, confirming that the target compound was 5-fluoro-ADB. The quantitative results obtained by selected reaction monitoring of LC–MS–MS showed the highest level, at 7.95 ng/g, in the adipose tissue, followed by stomach contents, brain, heart muscle, pancreas, and spleen. For the lung, liver, kidney, and skeletal muscle, levels were below the quantitation limit (about 0.5 ng/g), although very small peaks above the detection limit (about 0.1 ng/g) could be observed for all of the above solid tissues. The low levels of 5-fluoro-ADB in the solid tissues were likely as a result of only a small amount of 5-fluoro-ADB incorporated into the body via the lungs due to the short period from the beginning of smoking the herb to the fatal asphyxia resulting from aspiration of a massive amount of stomach contents into the trachea under low-consciousness conditions. In addition, we measured the content of 5-fluoro-ADB in three packages, all of which were opened, that were found under a pillow near the deceased; their levels of 5-fluoro-ADB were 49.2 mg/g, 12.2 μg/g, and 0.77 μg/g. To our knowledge, this is the first reported identification and quantitation of 5-fluoro-ADB in human specimens and herbal products.