A smartphone-integrated light-up lanthanide fluorescent probe for the visual and ratiometric detection of total phosphorus in human urine and environmental water samples

Phosphate (Pi) plays an essential role in aquatic ecosystems as well as in physiological processes. Here, a dual-emission probe for the sensitive, specific and visual analysis of Pi is fabricated by coordinating Eu3+ with luminol and 2,6-pyridinedicarboxylic acid (DPA). Pi can significantly enhance the characteristic fluorescence of Eu3+ at 615 nm by promoting energy transfer from DPA to Eu3+ and reducing the quenching effect of water molecule, luminol with inherent emission at 423 nm further enhances the Eu3+ fluorescence. Accordingly, ratiometric detection of Pi can be achieved with the fluorescence ratio F615/F423 as a function of Pi concentration. Linearity between F615/F423 and Pi concentration in the range of 0.1-25 μM is shown, and the limit of detection (LOD, 3σ/K) for Pi is 0.027 µM. In addition, a continuous change in the fluorescence color of the probe from blue to red is observed with increasing Pi concentration under a UV lamp, and a smartphone-based visual method is used for the convenient and effective semi-quantitative determination of Pi. The dual-emission probe has been successfully applied to ratiometric and visual analysis of Pi in human urine and environmental water samples, and adequate results are obtained.