Fragmentation of Moxifloxacin and Its Analogs by Electrospray Ionization Time-of-Flight Mass Spectrometry

Abstract

The fragmentation of patterns of moxifloxacin, 2-N-methylated moxifloxacin (analog 1), and 1-cyclopropyl-6,7-difluoro-8-methoxy-4-oxo-3-quinolinecarboxylic acid (analog 2) were investigated by electrospray ionization quadrupole time-of-flight tandem mass spectrometry in the positive-ion mode. Many unusual ions were detected in the tandem mass spectra of moxifloxacin. Although the structures of moxifloxacin and analog 1 were similar, the relative abundances of products varied greatly. Comparison of the relative abundances of the product ions that lost CO 2 or H 2 O and complementary product ions resulting from sequential four-membered hydrogen rearrangement showed that the differences were related to the protonation sites. The loss of HF, probably though the formation of an ion=neutral complex, is of scientific interest. The identities of the major product ions were confirmed by deuterium-labeling experiments that demonstrated an unusual loss of a deuterium atom. The major differences in fragmentation patterns were compared to previous reports in the literature.

A Single-Run HPLC–MS Multiplex Assay for Therapeutic Drug Monitoring of Relevant First- and Second-Line Antibiotics in the Treatment of Drug-Resistant Tuberculosis

“…Fragmentation mass spectra of all compounds are displayed in Supplementary Table S7. Repetitive fragment signals in the fragmentation mass spectrum of moxifloxacin and stable isotope-labeled D-moxifloxacin resembled published fragmentation patterns [44]. Two out of four known capreomycin components were identified [45], IA and IB, detected as double charged ions.…”