Used as a reference standard in pharmaceutical quality control for the detection and quantification of impurities in clopidogrel active pharmaceutical ingredient (API) and its formulations. It helps ensure the purity, safety, and consistency of clopidogrel drug products during manufacturing and stability testing. Commonly employed in high-performance liquid chromatography (HPLC) and related analytical methods to identify potential degradation products or synthesis by-products. Its presence is monitored to comply with regulatory guidelines set by pharmacopoeias such as USP, EP, and ICH.