Abstract
•The proposed fluorescence method can easily differentiate trace RS from its isomers.•The ratiometric sensor enabled RS to trigger the change of fluorescence color.•RS as low as 5.0 nM can be directly identified with the naked-eye within 2 min.•The ratiometric fluorescence sensing for RS was facile, rapid, and sensitive.
Visual detection is favorable for the field monitoring and routine analysis of environmental pollutants. Specially, the change of fluorescent color instead of fluorescence brightness is particularly convenient for the visual monitoring. In this study, a facile, rapid and sensitive ratiometric fluorescence sensor is developed for visual discrimination of trace resorcinol (RS) from its isomers and analogues. Specific coupling reaction between RS and dopamine (DA) generates fluorescent azamonardine (AZMON) within 2 min, and the blue fluorescence intensity increases with the RS concentration. Furthermore, after red light-emitting Au nanoclusters (AuNCs) are added into the mixture of RS and DA, the fluorescence signal at 656 nm keeps unchanged, and the fluorescence intensity at 460 nm is positively correlated with RS concentration. Moreover, the increasing concentration of RS triggers the obvious change of fluorescent color from red to blue based on the red background fluorescence of AuNCs, and RS as low as 5.0 nM can be directly identified with naked eye. Herein, the reference signal of AuNCs facilitates the ratiometric and visual sensing of RS. The proposed sensor has been successfully applied to determination of RS in real water samples, and is convenient for the routine analysis and field monitoring of trace RS.