Characterization of forced degradation products of torasemide through MS tools and explanation of unusual losses observed during mass fragmentation of drug and degradation products through density functional theory

Mass spectrometry tools (HRMS/LC-HRMS, MSn, and/or on-line HID exchange) were employed to establish mass fragmentation pattern of torasemide and to characterize its degradation products. During collision-induced dissociation, multiple rearrangement processes and unusual losses of sulfur (S), sulfanyl (HS center dot), sulfur dioxide (SO2), sulphinic acid radical (HSO2 center dot), sulfur monoxide (SO), carbon monoxide (CO), formyl radical (CHO center dot) and C5H3NOS were observed. The same were successfully explained by study of energy profiles, established by application of density functional theory (DFT). (C) 2017 Elsevier B.V. All rights reserved.