TY - JOUR T1 - Quantitation of N-demethylantipyrine in biological samples and isolation and characterization of its glucuronic acid conjugate. JF - Drug Metabolism and Disposition JO - Drug Metab Dispos SP - 288 LP - 295 VL - 6 IS - 3 AU - C E Hignite AU - C Tschanz AU - D H Huffman AU - D L Azarnoff Y1 - 1978/05/01 UR - http://dmd.aspetjournals.org/content/6/3/288.abstract N2 - An improved method for quantitating N-demethylantipyrine (N-DEM-AP) in urine by gas chromatography or gas chromatography-mass spectrometry has been developed. Recovery of greater than 90% of N-DEM-AP was achieved by extraction of the sample at pH 1 after addition of 3-amino-1-phenyl-2-pyrazolin-5-one. The coefficient of variation of replicate analyses was 8%. N-DEM-AP was excreted in the urine as a glucuronic acid conjugate. This conjugate was isolated from the urine of an individual receiving antipyrine and purified. The NMR and mass-spectral data are consistent with the conjugate being an O-glucuronide of N-DEM-AP in its enol form. ER -