A fatal case involving the highest ever reported 4-CMC concentration.

Synthetic cathinones comprise a large amount of substances present on the dark market, which creates an undeniably worldwide problem and still is posing a threat. A 22-year-old man was brought to the Emergency Room from a party, where he had ingested orally 20 g of mephedrone. The man exhibited a disorder of consciousness with no logical verbal contact and dilated pupils. Moreover, a metabolic acidosis was present. The patient died after an hour from an admission to the ER. Blood and vitreous humor collected during an autopsy were analyzed with the use of an ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-QqQ-MS/MS) with the use of C18 column in multiple reaction monitoring (MRM) mode. Both biological specimens were prepared using liquid-liquid extraction (LLE) with the use of ethyl acetate and 0.5 M ammonium carbonate water solution (pH 9). The limit of quantification (LOQ) of the method was 0.5 ng/ml in both matrices; precision and accuracy values did not exceed ±15%. Recovery of the method was in the range of 86.1%-102.7%. Determined concentrations of 4-CMC were 8542 and 9874 ng/ml in blood and vitreous humor, respectively. Other substances present in both biological materials were: atropine, diazepam, lidocaine, and its metabolite norlidocaine, as well as methcathinone and ethyl alcohol. The concentration presented in here described case is the highest ever reported 4-CMC concentration. Important aspect is also receiving other NPS by recreational users than intended, which lead to accidental poisoning (in presented case user assumed 4-CMC was 4-MMC).