In vitro monitoring picogram Roxithromycin in human urine using flow injection chemiluminescence procedure

A sensitive chemiluminescence method, based oil the enhancive effect of roxithromycin on the chemiluminescence reaction between luminol and hydrogen peroxide in a flow injection system, was proposed for the determination of roxithromycin. The increment of chemiluminescence intensity was linear with roxithromycin concentration in the range 1.0-1000 pg ml(-1) with the detection limit of 0.3 pg ml(-1) (3 sigma). At a flow rate of 2.0 ml min(-1). a complete analytical process could be performed within 0.5 min, including sampling and washing. with a relative standard deviation of less than 5%. The proposed procedure was applied successfully in the monitoring of roxithromycin in human urine Without any pretreatment procedures and it was found that roxithromycin in urine reached its maximum after orally administrated for two hours, presenting an excretive ratio of 4.6% in 12 h. With urinary excretion rate method, the total elimination rate constant k and half-life time t(1/2) of roxithomycin was calculated, which was 0.1831, 3.785 h.