Spectrofluorimetric Study of the Charge-transfer Complexation of Certain Fluoroquinolones with 2,3,5,6-tetrafluoro-p-bezoquinone

Abstract

A highly sensitive spectrofluorimetric method was developed for the first time, for the analysis of ten fluoroquinolones (FQs) antibacterials, namely amifloxacin (AMI), ciprofloxacin (CIP), difloxacin (DIF), enoxacin (ENO), enrofloxacin (ENR), lomefloxacin (LOM), levofloxacin (LEV), norfloxacin (NOR), ofloxacin (OFL) and pefloxacin (PEF) in their pharmaceutical dosage forms or in biological fluids through charge transfer (CT) complex formation with fluoranil (TFQ). The TFQ was found to react with these drugs to produce stable complexes and the fluorescence intensity of the complexes was greatly enhanced. The formation of such complexes was also confirmed by both infrared and ultraviolet-visible measurements.The different experimental parameters that affect the fluorescence intensity were carefully studied. At the optimum reaction conditions, the drug-TFQ complexes showed excitation maxima ranging from 270 to 285 nm and emission maxima ranging from 450 to 460 nm. Rectilinear calibration graphs were obtained in the concentration range 0.02 to 3.1 μg mL^-1 for the studied drugs. The method has been successfully applied to determine their pharmaceutical dosage forms with good precision and accuracy compared to official and reported methods as revealed by t- and F-tests. They also applied for the determination of studied drugs in human urine samples.