Determination of norfloxacin in human urine by capillary electrophoresis with electrochemiluminescence detection

A fast and sensitive approach that can be used to detect norfloxacin in human urine using capillary electrophoresis with end-column electrochemiluminescence (ECL) detection of Ru(bpy)(3)(2+) is described. The separation column was a 75-mu m i. d. capillary. The running buffer was 15 mmol L-1 sodium phosphate (pH 8.2). The solution in the detection cell was 50 mmol L-1 sodium phosphate (pH 8.0) and 5 mmol L-1 Ru (bpy)(3)(2+). The ECL intensity varied linearly with norfloxacin concentration from 0.05 to 10 mu mol L-1. The detection limit (S/N= 3) was 0.0048 mu mol L-1, and the relative standard deviations of the ECL intensity and the migration time for eleven consecutive injections of 1.0 mu mol L-1 norfloxacin (n = 11) were 2.6% and 0.8%, respectively. The method was successfully applied to the determination of norfloxacin spiked in human urine without sample pretreatment. The recoveries were 92.7 -97.9%.