THE USE OF LOW-ENERGY COLLISIONALLY ACTIVATED DISSOCIATION NEGATIVE-ION TANDEM MASS-SPECTROMETRY FOR THE CHARACTERIZATION OF DOG AND HUMAN URINARY METABOLITES OF THE DRUG BW-1370U87

Liquid chromatography (LC) combined with atmospheric pressure chemical ionization mass spectrometry was used to identify phase I and II meta bolites of the drug BW 1370U87 in dog and human urine. Additional anal ysis of individual high-performance liquid chromatograph fractions col lected from dog urine by combined gas chromatography/mass spectrometry identified one metabolite which was not detected by LC/MS methods. Us ing negative-ion LC/MS, the majority of BW 1370U87 metabolites in huma n urine were identified as glucuronic acid conjugates of phase I oxida tive metabolites. The negative-ion fragmentation produced by low-energ y collisionally activated decomposition (CAD), studied by tandem mass spectrometry experiments, confirmed that these compounds were drug-rel ated and allowed metabolite structures to be assigned. Product-ion spe ctra of the metabolites were dominated by the loss of neutral molecule s from even-electron deprotonated [M - H]- ions.