Facile Assay Method for Norfloxacin and Ciprofloxacin by Sequential Injection Chromatography

Sequential injection chromatography (SIC) is a simple, inexpensive, portable, reagent-saving, and environmentally benign separation technique. This paper reports the development of a facile assay method for norfloxacin (NF) and ciprofloxacin (CF) in their formulations (tablets and eye drops) using SIC. The analytes were rapidly chromatographed on a short C18 monolithic column (4.6 x 50 mm) at a flow rate of 30 mu L s(-1). An isocratic mode was adopted. The optimum mobile phase composition was 90% water, 10% acetonitrile, and 0.3% triethylamine at pH 3.0. Miniaturized fiber optic spectrometric devices were coupled to the SIC system for UV detection at 280 nm. Sufficient separation with a resolution of 1.6 and numbers of theoretical plates of more than 1500 was achieved. Additionally, acceptable peak shapes with peak symmetries of 0.89 and 0.92 for NF and CF, respectively, were obtained. The method was validated and found to be reliable (the recovery was 98.0-100.6%) and precise (the RSDs of intra-/inter-day precision were less than 2.0%). The method is also sensitive. The limits of detection were less than 0.27 mu g mL(-1). The provided method could be considered an industrial scale since the sample frequency was seven samples h(-1) and the total volume of consumed reagents was 11.5 mL.