Quantifying nitroaromatics via terminating their photoreduction catalyzed by Eosin Y

The environmental and safety concerns caused by nitroaromatic compounds (NACs) require a sensitive, reliable, and easy-to-use method for their detection. In this work, we observed that an ultrafast photobleaching occurred when the photoreduction of NACs catalyzed by eosin Y (EY) was terminated. Based on such a semi-cycle photocatalysis , a colorimetric method was developed to quantify NACs with a linear relationship between the pseudo-first-order kinetic constant ( k app ) of EY photobleaching and NACs concentration. This method exhibited a high sensitivity, low detection limit (6.57 ppb), and good anti-interference ability in the presence of various ions or organics in water matrices, enabling satisfactory quantification results for practical water samples. Moreover, the EY-based photocatalysis mechanisms inspires that the ultra-fast EY decoloration in the NAC solution was attributed to the fragment of the photoexcited EY molecule. This work provides a feasible photocatalysis-based NAC detection approach by applying a “off-the-shelf” probe.