High-performance liquid chromatographic determination of concentrations of the reversible H+/K+ ATPase inhibitor SK&F 97574 in plasma

A reversed-phase high-performance liquid chromatographic (HPLC) assay using ultraviolet spectrophotometric detection has been developed for the determination of the concentration of 3-butyryl-4-(2-methylphenylamino)-8-(2-hydroxyethoxy)quinoline (I) in rat, dog and human plasma. Prior to analysis, the protein in plasma samples was precipitated with acetonitrile containing 3-butyryl-4-(2-methylphenylamino)-8-methoxyquinoline to act as an internal standard. The supernatant layer was injected onto the HPLC column with no further clean-up. The assay requires 200 microliters of plasma and is precise and accurate within the range 25-1000 ng/ml. The mean within-run and between-run coefficients of variation were < 6% at 25 ng/ml and greater concentrations. The mean accuracy of quality control standards was generally within +/- 5% of the nominal concentration. Recovery of I and internal standard from plasma was approximately 100% over the entire assay range irrespective of species.