Facile assay method for norfloxacin and ciprofloxacin by sequential injection chromatography

Summary 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 × 50 mm) at a flow rate of 30 μL 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-/inte...