Analysis of ciprofloxacin by a simple high-performance liquid chromatography method

A simple and sensitive high-performance liquid chromatographic method is described for the quantitative analysis of ciprofloxacin in pharmaceuticals and human plasma. The method employs reversed-phase chromatography using an RP-C18 column with an isocratic mobile phase of acetonitrile-2% acetic acid aqueous solution (16:84, v/v), umbelliferone as an internal standard, and a flow rate of 1.0 mL/min. The UV detector is set at 280 nm. The limit of detection is 0.25 microM (S/N = 3, injection volume = 10 microL). The regression equations are linear (r > 0.9999) over a range between 0.51 approximately 130 microM for the pharmaceutical analysis of ciprofloxacin and 0.51 approximately 64.8 microM for the biological analysis of ciprofloxacin in human plasma. The intra- and inter-day relative standard deviation and relative error are less than 3.39% and 5.71%, respectively. All the recoveries are greater than 93.8%. This method is successfully applied in a pharmacokinetic study of a volunteer who receives a 500 mg ciprofloxacin tablet.