Flow injection analysis of tannic acid with inhibited chemiluminescent detection

Tannic acid was found to inhibit chemiluminescence of the luminol–H2O2 reaction catalyzed by Cu2+. The mechanism of inhibition was investigated by chemiluminescent spectra, UV–visible spectra and variation of reaction conditions. A flow injection method has been developed for the determination of tannic acid based on the inhibition of the chemiluminescence of the luminol–H2O2–Cu2+ system by tannic acid. The method is simple, selective and sensitive with a detection limit of 9×10−9 mol/l. It is effective to determine tannic acid in the range of 7×10−8–1×10−5 mol/l. The variation coefficient of eleven determination for 6×10−7 mol/l tannic acid is 2.5%. The method has been successfully applied to the determination of tannic acid in real Chinese gall and hop pellets samples.