Quantitation of some recently introduced antibacterial drugs using sudan III as chromogenic reagent

A simple, rapid, accurate and sensitive spectrophotometric method for the d etermination of norfloxacin (NRF), ofloxacin (OFL) and ciprofloxacin (CPF) is described. This method is based on the formation of an ion pair with sud an III in aqueous-acetone medium [40% (v/v) acetone]. The coloured products are measured at 567, 565 and 566 nm for NRF OFL and CPF respectively. The optimization of various experimental conditions is described. Beer's law is obeyed in the range 0.4-12.0, 0.4-8.8 and 0.4-10.4 mu g mL(-1) of NRF, OFL and CPF respectively. For more accurate results, Ringbom optimum concentra tion ranges were 0.8-11.2, 0.6-8.5 and 0.8-10.0 mu g mL(-1), respectively. The results obtained showed good recoveries of +/- 1.2, +/- 1.5 and +/- 1.7 % with relative standard deviations of 0.67, 0.83 and 1.08% for NRF OFL, an d CPF, respectively. The molar absorptivity and Sandell sensitivity were al so calculated. Applications of the proposed method to representative pharma ceutical formulations are successfully presented.