Isolation and structural elucidation of an unknown novel impurity in sulfasalazine by high performance liquid chromatography coupled to mass spectroscopy and toxicology prediction

Abstract

Sulfasalazine is authorised for the management of long-term inflammatory conditions, including ulcerative colitis as well as juvenile and adult rheumatoid arthritis. Using high performance liquid chromatography analysis, one unknown impurity with a level greater than 0.2% was found in prototype batches of sulfasalazine during production. The intended impurity under investigation eluted at retention time of around 33 min and had a relative retention time value of 1.79. Preparative high performance liquid chromatogram was used to isolate this unknown impurity from the crude sulfasalazine. A thorough examination of the ¹H-nuclear magnetic resonance spectroscopy (¹H-NMR) and mass spectrometry (MS) data revealed the structure of the novel impurity. The management of new impurity creation and the potential molecular pathways leading to its formation were also examined. A new sulfasalazine impurity was characterized and toxicology prediction data was also obtained.