Why caffeine is used in sst of hplc?

Caffeine is commonly used as a standard in the stability study testing (SST) of high-performance liquid chromatography (HPLC) due to its well-defined chemical properties and behavior. It serves as a reliable reference compound because it is readily available, easy to detect, and exhibits consistent retention times under various chromatographic conditions. Additionally, its relatively simple structure allows for straightforward analysis and quantification, making it an ideal choice for method validation and calibration in HPLC applications.