Sensitive analysis of tetrodotoxin in human plasma by solid-phase extractions and gas chromatography/mass spectrometry

A method to determine tetrodotoxin (TTX) in human plasma by solid-phase ext ractions and gas chromatography/mass spectrometry (GC/MS) is described. TTX in plasma samples was passed through Sep-Pak PS-2 extraction cartridges, T hen the compound was converted to 2-amino-6-hydroxymethyl-8-hydroxyquinazol ine (C9-base) under alkaline conditions and extracted with use of an OASIS HLB extraction cartridge. The C9-base was analyzed after trimethylsilyl der ivatization by GC/MS-selected ion monitoring. Recovery rates were 35.3-50.8 % and their coefficients of variation were not greater than 16.6%. The cali bration curve was linear in the range of 0.5-10.0 ng ml(-1) and the detecti on limit was 0.1 ng ml(-1). The coefficients of within-day and day-to-day v ariations were not greater than 11.8%. Actual determination of TTX in rat p lasma after intraperitoneal administration was also presented.