Hypochlorite Oxidation on RuO2-Based Electrodes: a Combined Electrochemical and In Situ Mass Spectroscopic Study

A ratiometric fluorescent probe combined with smartphone technology based on cellulose for the detection of hypochlorous acid

Hypochloric acid (HClO) is a reactive oxygen species (ROS). ROS is an important component that has antibacterial effects on the biological immune defense system. Therefore, the detection of HClO has become an unavoidable issue. This paper reports a cellulose-based fluorescent probe. Naphthalimide serves as the fluorescent group, and the methylthio group serves as the recognition site. The principle is that HClO can oxidise the methyl sulphide group to a sulphoxide. Under a 365 nm UV lamp, this ratiometric fluorescent probe emits a bright yellow green fluorescence, which turns blue after adding HClO. This probe uses more environmentally friendly and sustainable biomass resources, and has significant fluorescence characteristics compared to most reported probes. Its detection limit (LOD) is as low as 4.34 μM. The equilibrium constant K = 3.54 × 102 M-1 for the probe plus HClO. The response time is 30 s, and it has good specificity recognition and anti-interference ability. In addition, the probe has been successfully prepared into a fluorescent film, providing potential applications for the convenient detection of HClO. Finally, the probe will be combined with smartphone technology as a portable signal processing device to further achieve visual detection of HClO.

Green-emitting carbon quantum dots as a dual-mode fluorescent and colorimetric sensor for hypochlorite

In this work, green-emitting carbon quantum dots were successfully prepared through a facile one-step solid-state reaction method. The obtained green-emitting carbon dots (G-CDs) showed good fluorescence stability in NaCl aqueous solution and different pH values. Moreover, the G-CDs showed high sensitivity and selectivity for detecting hypochlorite by both fluorometry and colorimetry. Under the optimized condition, a highly sensitive detection of hypochlorite was established in the range of 0.2-100 μM and 10-150 μM for fluorescent and colorimetric methods, respectively. The corresponding limits of detection (LOD) were 0.0781 μM and 1.82 μM, respectively. Therefore, the G-CDs were successfully applied to determinate hypochlorite in actual water samples. In addition, a paper-based sensor loading with the G-CDs was also developed for rapid visual detection of hypochlorite. The results suggested that the G-CDs could be a promising candidate to detect hypochlorite.