High-performance liquid chromatographic assay of quinapril in tablets

A new, simple and accurate high-performance liquid chromatography (HPLC) method is presented for measuring of quinapril in tablets, using a reversed-phase technique and UV detection at 211 nm. The isocratic elution was used to quantify the analyte and the internal standard-perindopril. The samples were chromatographed on LiChrosorb RP-18 column and the mobile phase was phosphate buffer pH 2.5-acetonitrile (6:4, v/v). The method was linear between 0.1–0.5 mg ml⁻¹. Over the tested concentration range the intra-day coefficient of variation for replicate analyses in tablets ranged from 0.88 to 2.70%. The detection limit for the analysis of quinapril was 50 μg ml⁻¹ with 20 μl injection.