In Vitro Monitoring Chlorogenic Acid in Human Urine and Serum by a Flow Injection System Exploiting the Luminol-Dissolved Oxygen Chemiluminescence Reaction

A sensitive flow injection chemiluminescence method, based on the inhibitory effect of chlorogenic acid on the reaction between luminol and dissolved oxygen, was presented for the determination of chlorogenic acid. It was found that the decrease of chemiluminescence intensity was linear with the logarithm of chlorogenic acid concentration over the range from 1.0 ng·ml-1 to 100 ng·ml-1 (r2 = 0.9978), with the detection limit of 0.3 ng·ml-1 (3). At the 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 lower than 3.0% (n = 5). The proposed procedure was applied successfully to determine chlorogenic acid in Flo Lonicerae for different drawn time and monitor the excretion of chlorogenic acid in human urine. It was found that the excretive amounts of chlorogenic acid in urine reached its maximum in 2 hours after intake of Flo Lonicerae tea, presenting an excretive ratio of 63.82% in 6 hours. With urinary excretion rate method, the total elimination rate constant k and half-life time t1/2 of chlorogenic acid was calculated, which were 0.7667 and 0.91 hours, respectively. Keywords: Chlorogenic acid, chemiluminescence, luminol, dissolved oxygen, flow injection, Flo Lonicerae, human urine, excretive