Used primarily as a reference standard in pharmaceutical quality control and analytical testing. It serves as a known impurity in the synthesis and stability studies of rabeprazole, a proton pump inhibitor used to treat gastrointestinal disorders such as GERD and peptic ulcers. By comparing test samples against this impurity, manufacturers can monitor purity, optimize manufacturing processes, and ensure compliance with regulatory guidelines. Its presence helps in validating analytical methods like HPLC and LC-MS for accurate detection and quantification of impurities in drug substances and products.