Isolation and identification of the major degradation product in lansoprazole capsule during stability studies

The presence of unknown impurity of the order 0.2% was identified in the Lansoprazole Delayed Release Capsule using liquid chromatographic technique employing binary gradient system.Asimple high-performance liquidelectrospray ionization mass spectrometric method has been developed for the identification of unknown impurity in Lansoprazole Delayed Release Capsule. The ESI-MS results obtained allowed us to propose possible structure for its fragmentations. Structure elucidation using nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy was facilitated by developed rapid preparative isolationmethod. The impuritywas characterized as 1H–benzimidazole-2-thiol.