| Abstract: | The dioxopiperazine metabolites of quinapril in plasma and urine were extracted with hexane—dichloroethane (1:1) under acidic conditions. Following derivatization with pentafluorobenzyl bromide and purification of the desired reaction products using a column packed with silica gel, the metabolites were analysed separately by capillary column gas chromatography—electron-impact mass spectrometry with selected-ion monitoring. The limits of quantitation for the metabolites were 0.2 ng/ml in plasma and 1 ng/ml in urine. The limits of detection were 0.1 ng/ml in plasma and 0.5 ng/ml in urine, at a signal-to-noise ratio of > 3 and > 5, respectively. The proposed method is applicable to pharmacokinetic studies. |
