High-performance liquid chromatography of the drug fosenopril.

High-performance liquid chromatography was used to determine the purity and impurities of fosinopril, an angiotensin-converting enzyme inhibitor used to treat hypertension. Purity values are determined using a silica column and usually are above 99%. All known possible impurities, including stereoisomeric impurities, can be resolved and quantified by injecting solutions of fosinopril onto three separate columns; silica, strong anion exchange and phenyl. Typical impurity contents total 0.5%. Validation data and a study of properties of fosinopril in solution is included.