Ultrasensitive assay of gatifloxacin at picogram level based on its enhancing effect on the myoglobin-luminol chemiluminescence reaction

Picogram-level gatifloxacin was determined based on its significantly catalyzed effect on myoglobin-luminol chemiluminescence ( CL) reaction in the flow injection system. The enhanced chemiluminescence intensity was linear with gatifloxacin concentration in the range from 50 ngl(-1) - 10 mu g l(-1) (r(2) = 0.9995), and the detection limit was 20 ng l(-1) (3 sigma). At a flow rate of 2.0 ml min(-1) for each line, a complete analytical process could be performed within 0.5 min, including sampling and washing, with a relative standard deviation of less than 4.0% (n = 7). The proposed method was applied successfully in the determination of gatifloxacin in tablets, human serum and urine samples with the recovery from 97.4-104.5%.