A turn-off Eu-MOF@Fe2+ sensor for the selective and sensitive fluorescence detection of bromate in wheat flour

A new europium metal–organic framework ( Eu-MOF ) was prepared by simple hydrothermal method . The product exhibited intense red fluorescence, long fluorescence lifetime (0.454 ms) and excellent fluorescence stability. The fluorescence titration result showed that Fe 3+ could completely quench the fluorescence of Eu-MOF , while the fluorescence quenching effect of Fe 2+ or bromate was negligible. Considering the strong oxidizing property of bromate, a “turn off” Eu-MOF@Fe 2+ sensor toward bromate was designed by generating Fe 3+ due to the redox reaction . The results showed that the sensor displayed a wide linear range (0–0.2 mM), high sensitivity (LOD = 3.7 × 10 −6 mol/L), good selectivity and resistant to possible interferences in real four sample. Furthermore, the detection mechanism was investigated by PXRD, XPS and UV–Vis methods. More importantly, the Eu-MOF@Fe 2+ sensor was further applied to detect bromate in wheat flour with satisfactory recovery (95.30%−104.38%) and accuracy (RSD < 2.85%). These results suggest that Eu-MOF@Fe 2+ can be used as a potential sensor to detect bromate in food industry.