A single CDs/Fe-MOF luminescent probe with dual-emission for the simultaneous detection of nitrite and copper (II) ions.

Nitrite (NO2-) and copper (Cu2+) ions are widespread environmental pollutants that threaten both ecosystem integrity and human health, yet their simultaneous on-site detection remains challenging. To address this, we developed a dual-emissive luminescent probe by integrating 652 nm-emitting carbon dots (CDs) with a 445 nm-emitting Fe-MOF. This composite sensor enables the orthogonal detection of NO2- and Cu2+ within a single sample via distinct luminescence responses, the Fe-MOF emission at 445 nm is selectively enhanced by NO2-, while the CDs emission at 652 nm is specifically quenched by Cu2+. The sensor exhibited good sensitivity, with detection limits of 0.26 μM for NO2- and 0.31 μM for Cu2+ within a linear range of 0-20 μM. It also demonstrated excellent practicality, achieving recoveries of 94.0%-109.5% in real environmental and food samples. Furthermore, when coupled with machine learning to improve prediction accuracy, this CDs/Fe-MOF platform offers a reliable and cost-effective strategy for on-site monitoring of dual hazards in food safety and environmental protection.