%0 Journal Article %A C E Hignite %A C Tschanz %A D H Huffman %A D L Azarnoff %T Quantitation of N-demethylantipyrine in biological samples and isolation and characterization of its glucuronic acid conjugate. %D 1978 %J Drug Metabolism and Disposition %P 288-295 %V 6 %N 3 %X 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. %U https://dmd.aspetjournals.org/content/dmd/6/3/288.full.pdf