Atomic Absorption Spectrometric Determination of Certain Fluoroquinolones in Pharmaceutical Dosage Forms and in Biological Fluids

Simple, accurate, sensitive and selective methods are described for the quantitative determination of ten fluoroquinolones (amifloxacin, ciprofloxacin hydrochloride, difloxacin hydrochloride, enoxacin, enrofloxacin, lomefloxacin hydrochloride, levofloxacin, norfloxacin, ofloxacin and pefloxacin mesylate). The methods are based on precipitation of the ion associates formed from the reaction of the cited drugs with silver nitrate, copper acetate and ferric chloride. The formation and solubility of the solid complexes at the optimum conditions of pH and ionic strength values have been studied. The methods depend on direct determination of the ions in the precipitate or indirect determination of the ions in the filtrate by atomic absorption spectroscopy. The optimum conditions for precipitation were carefully studied. Rectilinear calibration graphs were obtained in the range of 10-100 ng.ml^-1 for each of the investigated drugs and the limits of detection and quantitation ranged from 1.125 to 2.260, o.937 to 2.754 and from 3.425 to 5.986 ng.ml^-1, respectively. The molar ratios of the formed chelats were determined by Job’s method and their association constants were also calculated. The developed methods were applied successfully for the determination of the studied drugs in their pharmaceutical dosage forms with good precision and accuracy compared to official and reported methods as revealed by t-and F-tests. They were also applied for the determination of studied drugs in spiked urine and plasma samples.