Spectrofluorimetric determination of fluoroquinolones in honey with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone in the presence of β-cyclodextrin.

A simple and sensitive spectrofluorimetric method was developed for the determination of four fluoroquinolone antibacterials namely norfloxacin (NOR), ofloxacin (OFL), ciprofloxacin (CIP) and gatifloxacin (GAT) in honey through charge transfer (CT) complex formation with 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), and then the inclusion complexes of FQs-DDQ with β-cyclodextrin (β-CD) were formed, which resulted in drastic fluorescence enhancement. The effect of several parameters including the concentration of reactants, reaction temperature, time and ultrasonic treatment on the efficiency of the proposed method involving CT reaction and inclusion interaction was systematically investigated. Under the optimum conditions, the limits of detection (LODs) for four FQs in honey varied from 11.6 to 15.4 μg/kg (signal-to-noise ratio (S/N) = 3). The intra- and interday relative standard deviations (RSDs) were 1.6-4.0 % (n = 5) for four FQs. The calibration graph was linear from 42.8 to 1346.8 μg/kg with correlation coefficients not less than 0.9905. The recoveries of four FQs at three different spiked concentrations in honey samples ranged from 80.9 % to 92.8 %. The results indicated that the method was successfully applied for analyzing FQs in honey.