A resonance Rayleigh scattering and colorimetric dual-channel sensor for sensitive detection of perfluorooctane sulfonate based on toluidine blue

This work described the use of a basic phenothiazine dye (toluidine blue, TB) as a resonance Rayleigh scattering (RRS) and colorimetric probe for the detection of perfluorooctane sulfonate (PFOS). Owing to the electrostatic interactions between TB and PFOS, TB in the presence of PFOS caused great enhancement of RRS signal at dual-wavelength ( I 345 nm and I 506 nm ) and the ratio changes of absorbance ( A 502 nm / A 630 nm ). The RRS enhancement was attributed to the absorption-rescattering resonance effect, the increase of the molecular size, and the enhancement of hydrophobicity. The analytical procedure was implemented by physically mixing TB, Britton-Robinson buffer solution, and PFOS solution (or sample solution) all-in-one, avoiding the tedious pre-derivatization or the preparation of nanoparticles. The whole approach was less than 8 min. Under the optimal conditions, the analytical performance was acquired. The linear ranges for RRS and colorimetry were 0.04–8.0 and 1.0–20 μmol/L, with detection limits of 4.2 nmol/L and 112 nmol/L, respectively. The RRS method was applied to the determination of PFOS in environmental water with recoveries of 93.2–106%. The dual-channel sensor is convenient, rapidly responsive, sensitive, and cost-effective, integrating the advantages of RRS and colorimetry. Graphical abstract