Used primarily as a reference standard in pharmaceutical quality control and analytical testing. It helps in identifying and quantifying impurities during the manufacturing of etoricoxib, a nonsteroidal anti-inflammatory drug (NSAID). Ensures the purity and safety of the final drug product by monitoring degradation products and synthesis byproducts. Employed in high-performance liquid chromatography (HPLC) and mass spectrometry (MS) for calibration and method validation. Also useful in stability studies to assess the shelf life of etoricoxib formulations.