Online Monitoringof Residual Pyrethroids in Indoorand Aquatic Environments: Advancing Fluorescence Sensing from Laboratoryto Field Deployment

Pyrethroids, despite their widespread use in agriculture and household pest control, are often overlooked as persistent and potential toxicity contaminants. Their extensive applications lead to ubiquitous indoor and environmental residues, thereby raising risks to aquatic ecosystems and human health; however, effective on-site monitoring tools remain lacking. Herein, we pioneered an advanced indoor and environmental sensing device, i.e., the first online monitoring system for real-time detection of residual pyrethroids in waters. By designing a coumarin derivative that exhibited rapid and selective fluorescence enhancement upon binding to pyrethroids, a reversible sensor immobilized on a glass substrate was developed. Integrated into a Portable Online Monitoring Equipment (POME), this system enabled continuous, in situ monitoring and full signal regeneration within 5 min. The present method demonstrates excellent selectivity, stability across waters, and minimal environmental impact by virtue of zebrafish (Danio rerio) toxicity assays. This work bridges the gap between laboratory analysis and field-deployable sensing, offering a powerful tool for tracking these under-monitored pollutants and advancing real-time water quality assessment.