A portable Eu-MOF-loaded paper-based probe integrated with smartphone for the visual and on-site detection of CrO in aqueous media.

The high toxicity of dichromate anion (CrO) its accurate necessitates its sensitive and effective detection to safeguard human health. The study introduces a Eu-MOF fluorescent probe, named as Eu-TDCA, synthesized using 2,5-thiophenedicarboxylic acid (HTDCA) as a bridging ligand for the detection of CrO in aqueous media. The probe suspension can detect CrO through fluorescence quenching, and the detection process exhibits a wide linear range (0-85 and 85-230 mg/L), low limit of detection (LOD, 5.1 μg/L) and rapid response speed (2 min). Furthermore, a portable Eu-TDCA-loaded paper-based probe, integrated with a smartphone color recognition app, was developed for the visual, sensitive and quantitative detection of CrO in real lake and river water samples, achieving satisfactory recoveries of 99.72%-103.75 %. Additionally, an advanced logic gate device was designed to simplify the detection process, providing a new direction for intelligent on-line detection of analytes.