EXTRACTION SPECTROPHOTOMETRIC DETERMINATION OF LIDOCAINE USING FLOW INJECTION ANALYSIS

A method to determine tetrodotoxin (TTX) in human plasma by solid-phase extractions and gas chromatography/mass spectrometry (GC/MS) is described. TTX in plasma samples was passed through Sep-Pak PS-2 extraction cartridges. Then the compound was converted to 2-amino-6-hydroxymethyl-8-hydroxyquinazoline (C9-base) under alkaline conditions and extracted with use of an OASIS HLB extraction cartridge. The C9-base was analyzed after trimethylsilyl derivatization 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 calibration curve was linear in the range of 0.5–10.0 ng ml−1 and the detection limit was 0.1 ng ml−1. The coefficients of within-day and day-to-day variations were not greater than 11.8 %. Actual determination of TTX in rat plasma after intraperitoneal administration was also presented.