Analytical determination of muscimol in post-mortem blood in a case of polydrug user

Muscimol (MUS), a GABA-A receptor agonist naturally occurring in Amanita species, is becoming available in commercial edible products marketed for recreational use. This study described the development and validation of an new SPE- HILIC-LC-MS/MS method for the determination of MUS in post-mortem blood and its application to a polydrug user consuming also MUS candies. The method was validated over a calibration range of 0.125-10 µg/mL, with a limit of detection of 0.06 µg/mL and a limit of quantification of 0.125 µg/mL; accuracy and precision were within acceptable limits, fitting the purpose of the study. In the reported case, MUS was quantified in central blood at 0.18 µg/mL. Elevated concentrations in urine (55 µg/mL) and gastric content (24 µg/mL) were consistent with recent oral intake occurring within the perimortem timeframe. The toxicological interpretation of MUS findings remained challenging due to the absence of published reference data in literature and the concomitant presence of multiple psychoactive substances in this case. This study provided new analytical and case-related data contributing to the limited forensic literature on MUS recreational consumption.