The First Reported Case of a Synthetic Cannabinoid Ethyl Ester Detected in a Postmortem Blood Toxicological Analysis.

Metabolites of synthetic cannabinoids (SCs) are widely used as markers for identifying SCs' intake. Polydrug use involving SCs and ethanol may generate new metabolites, namely SC ethyl esters, hereby shown for the first time as new blood markers of SC-alcohol concomitant abuse. We report a case involving both the presence of 5F-PB22 and ethanol and the detection of their transesterifcation product, namely 5F-PB22 ethyl ester, in a postmortem blood sample. This marker was found retrospectively in a preserved femoral blood analyzed via liquid chromatography-high-resolution mass spectrometry. A single-point calibration was used to estimate the concentration of 5F-PB22-Et in the sample, which found to be 0.4 μg/L. Retention time and fragment ions (within ±1 mmu extraction window) of 5F-PB22-Et in the sample gave a remarkable match with a synthetic reference material. To the best of our knowledge, this is the first case report of an SC ethyl ester in a biological sample to indicate SCs and ethanol co-consumption.