Characterization of forced degradation products of clozapine by LC-DAD/ESI-Q-TOF.

Forced degradation of clozapine in solutions under acidic, basic, neutral, photo UV-vis, photo UVC and oxidative stress conditions was investigated and structural elucidation of its degradation products was performed with the use of the UHPLC-DAD system coupled with accurate hybrid ESI-Q-TOF mass spectrometer. The developed method allows to collect all essential data for the determination of degradation kinetics and for the structural elucidation of the formed products. Six degradation products were found and their masses and formulas were obtained with high accuracy (0.61-3.75ppm). For all the analyzed compounds MS/MS fragmentation spectra were also obtained allowing structural elucidation of the unknown degradation products. It was found that the decomposition of clozapine yields the first-order kinetic reaction in all stress conditions and it is fragile towards acidic hydrolysis and oxidative conditions. Additionally, PCA analysis of registered TOF (MS) forced degradation profiles of clozapine shows no differences between the samples obtained from pharmaceutical formulation and bulk substance.