A Novel Colorimetric and Fluorescent Dual-Mode Probe for Hypochlorite and Its Application in Water Sample Detection

Hypochlorite (ClO‒) is an important reactive oxygen species (ROS), and is widely used in water treatment as the main component of disinfectants and bleaching agents. However, excessive ClO‒ can cause environmental damage and even lead to various human health issues. Therefore, efficient and convenient detection of ClO‒ is of great significance. In this study, a novel fluorescent probe (designated as EN) for ClO‒ detection was designed and successfully synthesized via a simple two-step route, using an anthraquinone derivative with a planar conjugated structure as the main framework. The absorption spectroscopy results of probe EN showed that the absorbance at 410 nm exhibited a good linear relationship with ClO‒ concentration in the range of 0.028–10 μmol/L. Fluorescence spectrum measurements indicated that under excitation at 380 nm, probe EN displayed a strong fluorescence emission peak at 543 nm. Upon addition of ClO‒, the emission peak at 543 nm gradually disappeared. Moreover, the fluorescence intensity at this wavelength also showed a good linear relationship with ClO‒ concentration over the range of 0.19–10 μmol/L. Probe EN enabled rapid colorimetric and fluorometric dual-signal detection of ClO‒ (response time5 s), with satisfactory limit of detection (LOD) (27.44 nmol/L for colorimetric detection and 180.24 nmol/L for fluorometric detection). Meanwhile, probe EN exhibited excellent selectivity and anti-interference ability, and could realize stable detection in the range of weak acid to weak base. Comparison with the current national environmental protection standard method revealed that the two sets of test results exhibited good consistency with excellent recovery rates, and the probe possessed outstanding accuracy and sensitivity, which confirmed the promising prospects of the probe EN for practical application.