A chitosan-mediated turn-on strategy for rapid fluorometric detection of perfluorooctane sulfonate

In this paper, a fluorometric method based on chitosan-mediated turn-on strategy was proposed for rapid detection of perfluorooctane sulfonate (PFOS). The method can be performed by two steps of simple physical mix. The whole procedure takes no more than 25 min. In pH 5.50 Britton-Robinson buffer solution, a green fluorescent dye (trisodium-8-hydroxypyrene-1,3,6-trisulfonate, HPTS) reacted with protonated chitosan to form complex by electrostatic attraction, leading in the strong quenching of HPTS. In the presence of PFOS, the fluorescence of HPTS recovered resulting from the electrostatic and hydrophobic interactions between PFOS and chitosan. The spectral characteristics, the reaction mechanisms of fluorescence quenching and fluorescence recovery, and the analytical conditions were investigated. Under the optimum conditions, a fluorometric method based on the chitosan-mediated turn-on strategy was developed for detection of PFOS. The value of fluorescence restoration (Delta F) was proportional to the concentration of PFOS in range of 0.0050-2.0 mu mol/L with correlation coefficient of 0.9949. The limit of detection (LOD) was calculated to be 1.0 nmol/L. The method was applied to the determination of PFOS in environment water with recoveries of 90.8-102% and RSD of 2.8-5.9%. The fluorometric method based on chitosan-mediated turn-on strategy is simple, rapid, sensitive and economical, showing potentiality for detection of PFOS in environmental water samples.