Masking Phosphate with Rare-Earth Elements Enables Selective Detection of Arsenate by Dipycolylamine-Zn ^II Chemosensor

Abstract

Functional reassessment of the phosphate-specific chemosensors revealed their potential as arsenate detectors. A series of dipicolylamine (Dpa)-Zn ^II chemosensors were screened, among which acridine Dpa-Zn ^II chemosensor showed the highest capability in sensing arsenate. The presence of excess Zn ^II improved sensitivity and strengthened the binding between acridine Dpa-Zn ^II complex to arsenate as well as phosphate. However, due to their response to phosphate, these sensors are not suited for arsenate detection when phosphate is also present. This study demonstrated for the first time that rare-earth elements could effectively mask phosphate, allowing the specific fluorescence detection of arsenate in phosphate-arsenate coexisting systems. In addition, detection of arsenate contamination in the real river water samples and soil samples was performed to prove its practical use. This sensor was further employed for the visualization of arsenate and phosphate uptake in vegetables and flowering plants for the first time, as well as in the evaluation of a potent inhibitor of arsenate/phosphate uptake.