An “Off–On” Rhodamine 6G Hydrazide-Based Output Platform for Fluorescence and Visual Dual-Mode Detection of Lead(II)
Xiaoqian Xie, Mingfei Pan, Liping Hong, Kaixin Liu, Jingying Yang, Shan Wang, Shuo Wang, Shuo Wang, Shuo Wang
Abstract
In this study, the rhodamine 6G hydrazide (R6GH) complex was synthesized to develop an “off–on” output platform for fluorescence and visual dual-mode analysis of lead(II) (Pb 2+ ). The prepared R6GH complex using the heat to reflux reaction of rhodamine 6G (R6G) and hydrazine hydrate was characterized through FT-IR, MS, 1 H NMR, and 13 C NMR and demonstrated to have good fluorescence stability and reversibility. The microenvironment for Pb 2+ detection has been optimized in detail. Under the optimal conditions, the “off–on” R6GH-based fluorescence output platform showed a good response to Pb 2+ in the concentration range of 0.05–6.0 μM ( R 2 = 0.9851) with a limit of detection (LOD) of 0.02 μM. Furthermore, at three spiked Pb 2+ levels in the selected agricultural (tap water, soil) and food (fish, shrimp) samples, the developed R6GH-based fluorescence assays obtained a significant recovery range of 84.0–102.0% (RSD < 5.0%, n = 3), which had a good correlation with the results from ICP-MS ( R 2 = 0.9915). The developed R6GH immobilized paper-based array sensor can reach the lower LOD (2.5 μM) for Pb 2+ through the naked eye. By combinin g with LAB analysis, a good linear response was obtained in the Pb 2+ concentration range of 1.0–50.0 μM. These results indicated that the developed R6GH probe had great application potential in accurate detection of fluorescence and rapid visual and semiquantitative screening for Pb 2+ .