Ratiometric fluorescent covalent organic frameworks for rapid detection of nitrofurans in aquatic products

Nitrofuran (NFs) antibiotics are widely employed in livestock and aquaculture to control bacterial and fungal infections. However, their excessive use has resulted in significant environmental contamination due to their persistence and potential carcinogenic, teratogenic, and mutagenic effects. In this study, we synthesized a fluorescent covalent organic framework (TzHTA) using 4,4',4″-(1,3,5-triazine-2,4,6-triyl) trianiline (Tz) and 2-hydroxybenzene-1,3,5-tricarbaldehyde (HTA). TzHTA exhibited dual fluorescence emission peaks at 520 nm and 660 nm, enabling effective NFs detection. The probe demonstrated good linearity for NFs within the range of 0.5-100 mg/L, with detection limits as low as 0.052-0.443 μmol/L. Furthermore, a smartphone-based fluorescence analysis method was developed for the quantitative detection. The method's performance was validated via spiking experiments using aquatic product samples, yielding recoveries comparable to high-performance liquid chromatography (HPLC). This study provides a rapid and sensitive approach for detecting NFs, offering significant potential for environmental monitoring and food safety applications.