Piretanide is primarily used as a reference standard in analytical testing for system suitability in pharmaceutical quality control. It ensures the reliability and accuracy of analytical instruments, particularly in high-performance liquid chromatography (HPLC) and related techniques. Due to its consistent chromatographic behavior, Piretanide helps verify system performance, including parameters like retention time, peak resolution, and theoretical plate count. It is especially valuable in validating methods used for the assay and impurity profiling of diuretic drugs. Its use in system suitability testing supports compliance with regulatory requirements by confirming that the analytical system is functioning properly before sample analysis.