Direct detection of serum psilocin glucuronide by LC/MS and LC/MS/MS: time-courses of total and free (unconjugated) psilocin concentrations in serum specimens of a “magic mushroom” user

Psilocin glucuronide (PCG) was directly identified in serum specimens of a “magic mushroom” user by liquid chromatography/mass spectrometry (LC/MS) and LC/MS/MS, together with the free (unconjugated) psilocin (PC). A major part of serum PC existed in the conjugated form. To quantify the total (conjugated plus free) PC in serum, enzymatic hydrolysis conditions were optimized using the user’s urine as the source of PCG; PCG in serum could be completely hydrolyzed by Escherichia coli β-glucuronidase. Using the established procedure, both total and free PC in the serum specimens of the user collected at various intervals were quantified. For the first specimen collected 5h after magic mushroom ingestion, 71.0 ng/ml of total PC and 13.3 ng/ml of free PC were detected. The ratio of free PC to total PC decreased with time after ingestion. The β-glucuronidase treatment of serum was found to clearly extend the detectable period of the serum PC; PC could be detected even 52 h after ingestion of magic mushroom.