Identification, characterization and quantification of a new impurity in deferasirox active pharmaceutical ingredient by LC–ESI–QT/MS/MS

An unknown impurity was detected in deferasirox drug substance by a newly developed high performance liquid chromatography (HPLC) method. The unknown impurity was identified by liquid chromatography–tandem mass spectrometry using electrospray ionization source and Q-trap mass analyzer (LC–ESI–QT/MS/MS). Based on LC–MS/MS data and knowledge of the synthetic scheme of deferasirox, this impurity was proposed as the regio-isomer of deferasirox. Structural confirmation of this impurity was unambiguously carried out by synthesis followed by characterization using nuclear magnetic resonance (NMR), infrared spectroscopy (IR), mass spectrometry, elemental analysis (EA) and the impurity was confirmed as 2-[3,5-bis(2-hydroxy-phenyl)-[1,2,4]-triazol-1-yl]-benzoic acid (Imp-1). The newly developed method was validated according to ICH guidelines. The resolution between Imp-1 and deferasirox was found to be more than 6.0 and the detection limit of impurities was in the range of 0.0005–0.01%, indicating high selectivity and sensitivity of the newly developed method.