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

Metabolites of synthetic cannabinoids are widely used as markers for identifying synthetic cannabinoids' intake. Polydrug use involving synthetic cannabinoids and ethanol may generate new metabolites, namely synthetic cannabinoid ethyl esters, hereby shown for the first time as new blood markers of synthetic cannabinoid-alcohol concomitant abuse. We report a case involving both the presence of 5F-PB22 and ethanol, and the detection of their transtesterifcation product, namely 5F-PB22 ethyl ester, in post mortem blood sample. This marker was found retrospectively in preserved femoral blood analysed 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 a synthetic cannabinoid ethyl ester in a biological sample to indicate synthetic cannabinoids and ethanol co-consumption.