An eosin Y-based "turn-on" fluorescent sensor for detection of perfluorooctane sulfonate

In this paper, a novel sensing method with a higher sensitivity of perfluorooctane sulfonate (PFOS) than perfluorooctanoic acid (PFOA) has been proposed detection of PFOS in aqueous solution replying on the "off-on" switch of eosin Y/polyethyleneimine (PEI)/PFOS fluorescence system due to the higher affinity of PEI to PFOS than eosin Y. In pH 7.0 Britton-Robinson buffer solution, eosin Y reacts with protonated PEI to form complex by electrostatic attraction, which leads to a strong fluorescence quenching of the eosin Y. When PFOS presents, the fluorescence of eosin Y is recover due to the electrostatic and hydrophobic interactions between PFOS and PEI. The recovered fluorescence intensity is proportional to the concentration of PFOS in the ranging from 0 to 2.0×10(-6) mol/L with the limit of detection (LOD, 3σ) being 1.5×10(-8) mol/L without preconcentration. In this study, the optimum reaction conditions and the interferences of foreign substances were investigated. In addition, the effects of PFOA, the analog of PFOS, on the fluorescence recovery of the system were also studied. The presented approach has been successfully used to detect PFOS in real samples with RSD ⩽2.9%.