%0 Journal Article %A C Fenselau %A P C Feng %A T Chen %A L P Johnson %T Stable isotope analysis by fast-atom bombardment labeling of UDP-glucuronic acid. %D 1982 %J Drug Metabolism and Disposition %P 316-318 %V 10 %N 4 %X Fast-atom bombardment mass spectrometry is found to provide a method for analysis of isotopes in the enzyme cofactor uridine-5'-diphosphoglucuronic acid, heretofore unsusceptible to mass-spectral characterization. This technique was used to determine optimal conditions for the introduction of 18O by acid-catalyzed exchange in H218O and to evaluate the loss of the isotope when labeled cofactor is used in enzymatic incubations. Fast-atom bombardment mass spectrometry provided a quantitative assessment of various isotopic species and also permitted the location of the isotopes in the molecule to be determined. %U https://dmd.aspetjournals.org/content/dmd/10/4/316.full.pdf