A sensitive gas chromatograph assay for thiopentone in plasma

A sensitive flame ionization gas chromatograph assay method has been developed for thiopentone in human plasma. The extraction procedure minimizes desulphuration of the drug while removing most endogenous substances and is limited by a maximum of 50 ng ml-1 in 2-ml plasma samples. There is linearity throughout the 30.0-5.0 microgram ml-1 and 5.0-0.1 microgram ml-1 ranges. Extraction of six replicate 2.5-microgram ml-1 samples resulted in a coefficient of variation of 3.0%. Similar treatment of six 0.20-microgram ml-1 samples afforded a coefficient of variation of 4.6%.