Simple measurement of captopril in plasma by high-performance liquid chromatography with ultraviolet detection.

Captopril is an orally active inhibitor of angiotensin-converting enzyme. A rapid, accurate, and sensitive high-performance chromatography (HPLC) method is described for measuring plasma concentrations of captopril. Captopril was stabilized by forming an adduct with p-bromophenacyl bromide. This adduct was measured by HPLC using a C-18 reverse-phase column and monitoring the column effluent by ultraviolet absorption at 260 nm. The method proved to be linear in the clinical range of 10-1,000 ng/ml. The plasma levels of captopril in a young patient given a small oral dose were determined by this method.