A sensitive spectrofluorimetric method was developed for
determination of ciprofloxacin (CPFX), levofloxacin (LEV), gatifloxacin (GAT)
and moxifloxacin (MOX) in pure, commercial formulations, human urine and
plasma. The method is based on charge-transfer (CT) complex with chloranilic
acid. Fluorescence intensity of the complexes was measured at emission
wavelength ranging from 445-492 nm with excitation wavelengths from 285-330 nm.
At optimum experimental conditions, a linear calibration plot was obtained in
the concentration range of 20-1000 ng·mL-1, 60-320 ng·mL-1,
20-800 ng·mL-1 and 20 -00 ng·mL-1 for CPFX, LEV, MOX and GAT, respectively with good correlation coefficient in
the range of 0.9929-1.0 in methanolic medium. The limit of detection and limit of
quantification were found to be 5 ng·mL-1 and 18 ng·mL-1 for
CPFX, 12 ng·mL-1 and 40 ng·mL-1 for LEV, 8 ng·mL-1 and 19 ng·mL-1 for MOX, 6 ng·mL-1 and 19 ng·mL-1 for GAT, respectively. The method was found free of interferences from excipients
used as additive in pharmaceutical preparations, some common cations and
compounds present in urine and plasma as well as co-administered analgesic, vitamins
and other drugs. The method was successfully applied for quantification of
selected fluoroquinolones in commercial formulations and also in spiked human
urine and plasma samples with percent recoveries of 100.0 ± 1.56 and 100.2 ±
1.29 respectively.