Quantitation of psilocin in human plasma by high-performance liquid chromatography and electrochemical detection: comparison of liquid–liquid extraction with automated on-line solid-phase extraction

Two modifications of an HPLC-ED method for measuring psilocin, the active metabolite of psilocybin, in human plasma were developed and compared. One used liquid-liquid extraction (LLE) and the other automated on-line solid-phase extraction (on-line SPE). Both methods had a limit of quantitation of 10 ng/ml psilocin and showed no significant difference in standard deviation (LLE 1.82%, on-line SPE 1.13%) or analytical results. On-line SPE required less manual effort, smaller plasma volumes (400 microl versus 2 ml), and achieved nearly 100% recovery of psilocin (LLE 88%). Both methods were rapid, simple, and reliable, and were successfully used to quantify psilocin in plasma samples from healthy volunteers after oral administration of 0.2 mg psilocybin per kg body mass.

Study at a glance

Abstract

Two modifications of the HPLC-ED method with respect to extraction procedure used have been developed for psilocin, the active metabolite of psilocybin, in human plasma using either liquid-liquid extraction (LLE) or automated on-line solid-phase extraction (on-line SPE). Each type of the sample preparation required a different HPLC system followed by electrochemical detection at 650 to 675 mV. The limit of quantitation of both modifications was 10 ng/ml psilocin. There was no significant difference observable between the LLE and the on-line SPE in terms of method standard deviation (LLE 1.82%, on-line SPE 1.13%) and the analytical results. However, the advantages of on-line SPE in addition to different selectivity were less manual effort, smaller plasma volumes of 400 microl (LLE 2 ml) and a recovery of psilocin in human plasma of nearly 100% (LLE 88%). In contrast to a previous procedure both methods were rapid, simple and reliable and yielded high plasma recoveries. They were used successfully in the quantitation of psilocin in plasma samples obtained from healthy volunteers after p.o. administration of 0.2 mg psilocybin per kg body mass. Plasma concentration curves and pharmacokinetic parameters were calculated.