Used primarily as an impurity reference standard in pharmaceutical quality control, particularly in the analysis of prochlorperazine formulations. It serves as a critical tool in HPLC and other analytical methods to detect and quantify degradation products, ensuring drug stability and safety. Its presence helps validate analytical procedures and assess the purity of active pharmaceutical ingredients. Also used in research settings to study metabolic pathways and oxidation products of phenothiazine antipsychotics.