Determination of ciprofloxacine, norfloxacine, and ofloxacine by high performance liquid chromatography.

A fast, versatile and precise method is described for the determination of quinolone derivatives in biological fluids and tissues by high performance liquid chromatography (HPLC) and fluorescence detection. Using a solvent consisting of acetonitrile/methanol/water/tetrabutylammoniumhydroxide (pH 3.0) and reversed phase material (5C18), ciprofloxacine, norfloxacine and ofloxacine were identified within 10 min, with a detection limit of 10 pg (ofloxacine 40 pg). No interference with other substances was observed. The sample preparation needs only one dilution and centrifugation step (recovery in blood, serum and urine about 100%). Ciprofloxacine, norfloxacine and ofloxacine are not degraded when incubated at 4 degrees C or 37 degrees C for 24 h in serum and urine. In heparinized blood ofloxacine remains stable, whereas a decrease of 25% (ciprofloxacine) and 30% (norfloxacine), respectively, is observed after 24 h at 37 degrees C without the formation of fluorescent metabolites. In serum and urine of treated patients, however, metabolites are detected. These findings suggest a metabolization process in organs, e.g. the liver.