Application of a hybrid ion trap/time-of-flight mass spectrometer in metabolite characterization studies: Structural identification of the metabolism profile of antofloxacin in rats rapidly using MSn information and accurate mass measurements

We describe herein, a very effective way in the rapid identification of metabolites for antofloxacin based on a hybrid ion trap (IT)/time-of-flight (TOF) mass spectrometer technique. The purified samples were separated by a reversed-phase C18 column under a gradient elution, antofloxacin and its metabolites were detected by the on-line IT/TOF detector in scan mode. The identification of the metabolites and elucidation of their structure were performed by comparing the changes in molecular masses (ΔM), calculating compound-based component by Formula Predictor software, and defining sites of biotransformation based upon mass shifts of diagnostic fragment ions according to the accurate MSn spectral information. In this case, we used such strategies for the identification of the metabolism for antofloxacin, and six metabolites of antofloxacin were found in rats for the first time.