Liquid-chromatographic determination of ciprofloxacin in serum and urine

We describe the liquid-chromatographic determination of ciprofloxacin in patients' serum and urine. Serum samples were prepared by precipitating protein with perchloric acid. Urine samples were diluted 100-fold with mobile phase. The mobile phase, consisting of pH 3 phosphate buffer/acetonitrile/methanol (81/5/14, by vol), was pumped through a mu Bondapak C18 reversed-phase column at 1.5 mL/min. Fluorescence of the effluent was monitored, at wavelengths for excitation and emission of 270 and 440 nm, respectively. Standard curves were linearly related to concentration from 0.08 to 10 mg/L for serum, 1 to 20 mg/L for urine. The procedure was evaluated in a clinical setting to determine its usefulness in studying the pharmacokinetics of ciprofloxacin in patients with concurrent diseases and receiving multiple drug therapies.