Fluorescence turn-on detection of tannic acid using a 6,7-dihydroxycoumarin-Fe3+ complex

Tannic acid (TA) is a natural polyphenolic compound widely distributed in plants and is extensively associated with medicine, food and leather. In this study, we developed a highly sensitive turn-on fluorescent probe for TA using an ensemble of 6,7-dihydroxycoumarin (DHC) and Fe3+ (DHC-Fe). DHC-Fe exhibited high selectivity over gallic acid and vitamin C, which avoided sample pretreatment so that simplified the detection process. Furthermore, DHC-Fe was successfully applied to detect TA in vegetable-tanned leather and in beverage samples. A portable paper-based TA sensor was prepared and allowed simple detection.