Investigation of the Metal Bonding Properties of Fluoroquinolone Type Antibiotics Using Spectrofluorimetric Method

The metal bonding properties of fluoroquinolone type antibiotics, namely levofloxacin and ciprofloxacin, were investigated by using spectrofluorimetric method. Fluorescence quenching of levofloxacin (LEV) and ciprofloxacin (CIP) by Fe (III) has been studied. The optimal experimental conditions were determined. The excitation and emission wavelengths were λex= 390 nm and &lambdaem= 500 nm for the Fe (III)-LEV complex and λex= 370 nm and &lambdaem= 462 nm for the Fe(III)-CIP complex at pH 5.5 in water medium. The calibration curves were obtained from Stern- Volmer equation plotting to F0/F-[Fe+3] graphs and the linearity was found within the range of 0.056-0.56 μg.mL-1 for the Fe(III)-LEV complex and 0.56-5.58 μg.mL-1 for the Fe(III)-CIP complex under the optimal conditions. The detection limits (LOD) of the proposed method for the Fe(III)-LEV and Fe(III)-CIP complexes were 1.6 ng.mL-1 and 5.9 ng.mL-1 respectively and the quantitation limits (LOQ) of these complexes were found to be 5.3 ng.mL-1 and 19.7 ng.mL-1 respectively. The stochiometry of both complexes was also determined by using the continuous variation method and the molar ratio of Fe(III):Fluoroquinolone was calculated as 2:3. The interaction between the fluoroquinolones in tablet forms and Fe(III) in the vitamin-mineral combination tablet was investigated by applying this quenching method and obtained satisfactory results.