Fluorescent and Colorimetric Dual-Mode Strategy Based on Rhodamine 6G Hydrazide for Qualitative and Quantitative Detection of Hg(2+) in Seafoods

In this study, a rapid fluorescent and colorimetric dual-mode detection strategy for Hg(2+) in seafoods was developed based on the cyclic binding of the organic fluorescent dye rhodamine 6G hydrazide (R6GH) to Hg(2+). The luminescence properties of the fluorescent R6GH probe in different systems were investigated in detail. Based on the UV and fluorescence spectra, it was determined that the R6GH has good fluorescence intensity in acetonitrile and good selective recognition of Hg(2+). Under optimal conditions, the R6GH fluorescent probe showed a good linear response to Hg(2+) (R(2) = 0.9888) in the range of 0–5 μM with a low detection limit of 2.5 × 10(−2) μM (S/N = 3). A paper-based sensing strategy based on fluorescence and colorimetric analysis was developed for the visualization and semiquantitative analysis of Hg(2+) in seafoods. The LAB values of the paper-based sensor impregnated with the R6GH probe solution showed good linearity (R(2) = 0.9875) with Hg(2+) concentration in the range of 0–50 μM, which means that the sensing paper can be combined with smart devices to provide reliable and efficient Hg(2+) detection.