FULLY AUTOMATED HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY OF CIPROFLOXACIN WITH DIRECT-INJECTION OF PLASMA AND MUELLER-HINTON BROTH FOR PHARMACOKINETIC PHARMACODYNAMIC STUDIES/

An isocratic high-performance liquid chromatographic method with colum n switching and direct injection has been developed to determine cipro floxacin in plasma and Mueller-Hinton broth. An on-line dilution of th e sample was performed with a loading mobile phase consisting of 173 m M phosphoric acid. The analyte was retained on a LiChrocart 4-4 precol umn filled with a LiChrospher 100 RP18, 5 mu m. An electric-actuated s ystem with two six-port valves allowed a clean-up step with a mixture 20 mM phosphate buffer (pH 3.5)-methanol (97: 3, v/v) and the transfer of the analyte by a back-flush mode to a 150x4.6 mm LD. column packed with a Kromasil C-8 5 mu m, using a mobile phase of 20 mM phosphate b uffer (pH 3.5)-acetonitrile (85:15, v/v). Fluorescence detection allow ed a quantification limit of 0.078 mu g/ml with a 40-mu l sample size. The method was evaluated to determine its usefulness in studying the pharmacokinetic/pharmacodynamic behaviour of ciprofloxacin in an in vi tro model. (C) 1998 Elsevier Science B.V. All rights reserved.