An “Off–On” Rhodamine 6G Hydrazide-Based Output Platform for Fluorescence and Visual Dual-Mode Detection of Lead(II)

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) (Pb2+). The prepared R6GH complex using the heat to reflux reaction of rhodamine 6G (R6G) and hydrazine hydrate was characterized through FT-IR, MS, 1H NMR, and 13C NMR and demonstrated to have good fluorescence stability and reversibility. The microenvironment for Pb2+ detection has been optimized in detail. Under the optimal conditions, the “off–on” R6GH-based fluorescence output platform showed a good response to Pb2+ 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 Pb2+ 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 Pb2+ through the naked eye. By combining with LAB analysis, a good linear response was obtained in the Pb2+ 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 Pb2+.

Detection of Heavy Metal Ions by Ratiometric Photoelectric Sensor

“…However, expensive equipment, complicated pretreatment, and long detection period are hard to overcome. 15,16 In contrast, the sensing method has not only a low detection limit, high sensitivity, and simple pretreatment but also the ability to measure multiple HMs simultaneously. Therefore, it accounts for the largest proportion of HMs detection in the recent 10 years, reaching 39%.…”

“…They are systemic toxicants that can induce multiorgan damage even at low exposure levels. 15 Air and foods are essential to human's life. However, they are easily exposed and polluted by HMs and thus endangering health through direct contact with the human body.…”

Dual-Mode Optical Sensor Array for Detecting and Identifying Perillaldehyde in Solution Phase and Plant Leaf with Smartphone

“…The R6G-N 2 H 4 adduct was sparked via reacting rhodamine 6G (R6G) with hydrazine hydrate (N 2 H 4 ·H 2 O) and characterized properly in the Supporting Information. , Its stock solution was prepared at 70.0 μM in ethanol. The SQ-N 2 H 4 adduct ( c ∼ 50.0 μM) was also obtained by mixing squaraine (SQ) in ethanol with a certain amount of N 2 H 4 .H 2 O.…”

“…Considering the reactive aldehyde group in perillaldehyde, , various strategies have been established for detecting and identifying perillaldehyde based on imine, condensation of hydrazine reaction mechanisms, 2-aza-Cope rearrangement, etc. − Colorimetric and fluorescent analyses have emerged as powerful optical technologies by virtue of the advantages of good selectivity, high sensitivity, and simple on-site visual and quantitative detection . The dual-mode output platform can also realize portable detection and ensure the detection reliability in practical applications. , Another thing that needs to be noted is that the rapid development of smartphone technologies with high-resolution camera, GPS capabilities, and Internet connectivity have opened doors for the quantitative on-site detection of the interesting substances . Meanwhile, taking into account that most reported probes were generally designed for a specific analyte instead of multiparameter detecting, photoelectric sensor array can be developed to recognize the overall contents to complex mixtures based on the cross-interaction of multiple sensing materials.…”

“…13 The dual-mode output platform can also realize portable detection and ensure the detection reliability in practical applications. 14,15 Another thing that needs to be noted is that the rapid development of smartphone technologies with high-resolution camera, GPS capabilities, and Internet connectivity have opened doors for the quantitative on-site detection of the interesting substances. 16 Meanwhile, taking into account that most reported probes were generally designed for a specific analyte instead of multiparameter detecting, photoelectric sensor array can be developed to recognize the overall contents to complex mixtures based on the cross-interaction of multiple sensing materials.…”