A novel flow injection chemiluminescence method for the determination of indole-3-acetic acid in biological samples by using trivalent silver

In this paper, a novel flow-injection chemiluminescence method was developed for the determination of indole-3-acetic acid (IAA). The chemiluminescence signal from the reaction of an Ag(III) complex and a sulfuric acid system was enhanced in the presence of IAA. The conditions of the CL system were investigated and optimized. Under the optimal conditions, the relative chemiluminescence intensity was linear with the IAA concentration in the range of 1.0 x 10(-10) g mL(-1) to 1 x 10(-8) g mL(-1). The detection limit for IAA was 7.7 x 10(-11) g mL(-1), and the relative standard deviation (n = 11) was 0.5%. The proposed method was applied to the analysis of IAA in human urine, mung bean sprouts and soil samples with recoveries of 103.5-117.1%, 87.0-98.4% and 94.1-118.8%, respectively, and the relative standard deviations was 0.6-2.7%. The results obtained by the proposed method agreed well with those obtained from the HPLC method. The chemiluminescence mechanism is discussed by comparison of fluorescence spectra and the UV-vis absorption spectra.