Acetyl fentanyl is an illicit fentanyl analog recently appearing in forensic casework. A quantitative method was created for measuring acetyl fentanyl in various biological matrices acquired post-mortem due to recent positive screening results in casework. Initial detection by immunoassay and standard gas chromatography mass spectrometry (GC/MS) methods have been previously reported for acetyl fentanyl and are examined further here. A Selective Ion Monitoring (SIM) method was created using a GC/MS for quantitation. In two separate cases, acetyl fentanyl was found to be in similar concentrations to those previously reported and ruled to be the cause of death. Acetyl fentanyl concentrations were determined in blood samples, liver, brain, vitreous humor, and urine. Individual 1 had acetyl fentanyl concentrations as follows: heart blood-285 ng/mL, femoral blood-192 ng/mL, liver-1,100 ng/g, brain-620 ng/g, and urine-3,420 ng/mL. Individual 2 had acetyl fentanyl concentrations as follows: heart blood-210 ng/mL, femoral blood-255 ng/mL, urine-2,720 ng/mL and vitreous humor-140 ng/mL. Experimental conditions for screening and quantitation are provided, using immunoassay and GC/MS methods. Due to the recent emergence of acetyl fentanyl, more data will need to be generated to fully differentiate recreational and fatal concentrations of acetyl fentanyl to assist toxicologists accurately understanding its physiological impact.

The focus of this study was to determine the stability of four synthetic cannabinoids, XLR-11, UR-144, AB-Pinaca and AB-Fubinaca in biological specimens for the purpose of casework processing prioritization. The study used human whole blood spiked with the compounds of interest to mimic real forensic laboratory samples submitted for synthetic cannabinoid analysis. The spiked whole blood specimens were incubated under one of three temperature conditions: room or ambient (22°C), refrigerated (4°C) and frozen (-20°C) for a period of 12 weeks. Study specimens were then extracted using a forward alkaline extraction at pH 10.2 and analyzed using a liquid chromatograph tandem mass spectrometer (LC-MS-MS). Under all incubation conditions results showed that AB-Fubinaca, AB-Pinaca and UR-144 were relatively stable while XLR-11 significantly degraded at ambient and refrigerated conditions. Frozen storage conditions were the only tested parameter able to preserve and stabilize all four compounds over the three month period. Therefore, it should be suggested that forensic blood evidence suspected of containing synthetic cannabinoid compounds should be stored in frozen conditions.

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