Spectrofluorometric determination of certain quinolone through charge transfer complex formation

A spectrofluorimetric method was developed for the determination of three fluoroquinolones antibacterials, namely, ofloxacin (OFL), levofloxacin (LEV), lomefloxacin (LOM), and pipemidic acid (PIP) through charge transfer (CT) complex formation with 7,7,8,8-tetracyanoquinodimethane (TCNQ). TCNQ was found to react with these drugs to produce stable complexes and the fluorescence intensity of the complexes was enhanced in 15-90 times higher than that of the studied drugs itself. The formation of such complexes was also confirmed by both infrared and UV-vis measurements. The different experimental parameters that affect the fluorescence intensity were carefully studied, At the optimum reaction conditions, the rectilinear calibration graphs were obtained in the concentration range 0.02-2.2 mug ml(-1) for the investigated drugs and the limits of detection ranged from 0.006 to 0.016 mug ml(-1). The proposed procedures could be applied successfully for the determination of the investigated drugs in their pharmaceutical dosage forms with a good precision and accuracy compared to official and reported methods as revealed by t- and F-tests. Also they were applied to determine spiked urine and plasma samples. (C) 2004 Elsevier B.V. All rights reserved.