GLC microanalyses of phenacetin and acetaminophen plasma levels.
A GLC method utilizing a flame-ionization detector is described for the simultaneous analysis of acetaminophen and phenacetin in plasma. p-Bromoacetanilide is used as an internal standard. The drugs are extracted with ether from plasma diluted with 1 M phosphate buffer (pH 7.4). The ether extract is evaporated to dryness under nitrogen, and the residue is dissolved in 300 microliter of ethyl acetate. The ethyl acetate is transferred to a microcentrifuge tube (0.4 ml), and the sample is evaporated in a vacuum centrifuge. Then  the residue is redissolved in 0.2 M trimethylanilinium hydroxide in methanol for GLC analysis. Extraction  efficiency of added phenacetin and acetaminophen in  plasma at concentrations of 1-10 microgram/ml was complete, and the limit of detection in plasma was less than 0.1 microgram.
D000082:Acetaminophen / Q000097:blood*; D000328:Adult; D002849:Chromatography, Gas; D006801:Humans; D008722:Methods; D008832:Microchemistry; D010615:Phenacetin / Q000097:blood*
D000082:Acetaminophen; D010615:Phenacetin