High-pressure liquid chromatographic determination of acetaminophen in biological fluids

A method for the rapid estimation of free acetaminophen in biological fluids is described. The assay involves either extraction and high-pressure liquid chromatographic analysis on a 10-mum particle-size silica gel column, using a mobile phase of 10% chloroform in tetrahydrofuran. The procedure was used to determine acetaminophen levels in urine from two healthy volunteers who ingested 650 mg of 14C-acetaminophen (20 muCi), and the accuracy of the method was compared with the carbon-14 determination. The limit of detectability for acetaminophen is 1 mug/ml.