Stability of plasma gamma-hydroxybutyrate determined by gas chromatography-positive ion chemical ionization-mass spectrometry

An effective method for the determination of gamma-hydroxybutyric acid (GHB) in human plasma is described that utffizes a simple liquid-fiquJd extraction procedure and gas chromatography-positive ion chemical ionization.mass spectrometry (GC-PCI-MS). The method has been used to study the stability of plasma GHB under several storage conditions. Following the extraction with acetonitrile, GHB and deuterated GHB (GHB-d6) were derivatized with N,O.bis[trimethylsilyl] trlfluoroacetamide (BSFTA). After the separation on a capillary GC column, the derivatives were ionized with ammonia reagent gas and analyzed by MS. The lower limit of quantitation in 100 pL of plasma was 2.5 pg/mL, over a range from 2.5 to 250 pg/mL. The coefficients of variation did not exceed 3.9 % and the mean measured concentrations did not deviate more than 8 % from the target for both intra- and interassay precision and accuracy