Rapid on-site SERS detection of difenoconazole and flusilazole in environmental water using an AuNSs/COF-based plate

We developed an on-site surface-enhanced Raman scattering (SERS) sensor for rapid detection of difenoconazole (DIF) and flusilazole (FLU) in environmental water. The substrate combines gold nanostars (AuNSs) with covalent organic frameworks (COF) and is implemented on a portable round 20-well quartz plate, enabling in situ testing. After a simple filtration process, environmental water can be directly dripped onto the SERS-active AuNSs/COF composite, thereby simultaneously achieving the adsorption of the target compound and SERS detection. There is a good linear relationship between the SERS intensity of the characteristic peak and the logarithmic concentration of the analyte, with correlation coefficients (R 2 ) from 0.923 to 0.986, meeting the monitoring needs of non-laboratory scenarios. The entire workflow completes within 9 min, offering a faster alternative to conventional methods while maintaining high sensitivity and reproducibility. Detection limits reach 0.88–1.17 ppb for DIF and FLU. Distinct SERS fingerprints enable reliable discrimination of mixed pesticides across environmental water, supporting rapid on-site monitoring and cost-effective pesticide surveillance. Graphical