omeprazole Imp-C (sulphide)

Omeprazole Imp-C (sulphide) is a benzimidazole-based impurity arising from the reduction of the sulfinyl bridge in the parent proton pump inhibitor. It features a pyridine ring linked via a sulfide (-S-) moiety to the benzimidazole core, differing from omeprazole by the absence of sulfoxide oxidation. This structural modification disrupts the zwitterionic character critical for acid suppression. It serves as an HPLC reference standard for quantifying process-related impurities in omeprazole drug substances.