A rhodamine B-based dual-mode ratio probe for colorimetric and fluorescent detection of perfluorooctanoic acid

A dual-mode ratiometric optical strategy is developed for determination of PFOA. • PFOA induces RhB aggregation via hydrophobic interactions, realizing spectral signal regulation. • The sensing strategy does not require any probe preparation process. • Homogeneous intermolecular reactions make the analytical method stable and reliable. Owing to its persistent “forever chemical” nature, perfluorooctanoic acid (PFOA) poses long-term environmental and health risks even under strict regulation, requiring low-cost continuous monitoring. In this work, a dual-mode ratiometric optical strategy was developed for colorimetric and fluorescent detection of PFOA using commercially available rhodamine B without complex synthesis. Under acidic conditions (pH = 1.0), PFOA induces the aggregation of rhodamine B through electrostatic and hydrophobic interactions, leading to the attenuation of monomer signals (UV–Vis absorption peak at 557 nm, fluorescence emission peak at 586 nm) and the enhancement of aggregate signals (UV–vis absorption peak at 593 nm, scattering peak at 557 nm). Accordingly, a dual-mode ratiometric optical sensing platform is constructed for the quantitative detection of PFOA. The limit of detection was 4.6 μM for colorimetry and 3.1 μM for fluorescence. This sensing strategy is not suitable for quantitative analysis of trace PFOA in drinking water due to its sensitivity limitations. However, it may be applicable for monitoring of the discharge of PFOA-containing wastewater from factories and emergency responses to sudden PFOA pollution incidents due to its low cost, stable signal, and ease of on-site operation, offering a practical alternative to complex nanomaterial-based sensors for high-concentration scenarios. Owing to its persistent “forever chemical” nature, perfluorooctanoic acid (PFOA) poses long-term environmental and health risks even under strict regulation, requiring low-cost continuous monitoring. In this work, PFOA induces the aggregation of rhodamine B through hydrophobic interactions under acidic conditions, leading to the attenuation of monomer signals (UV–vis absorption peak at 557 nm, fluorescence emission peak at 586 nm) and the enhancement of aggregate signals (UV–vis absorption peak at 593 nm, scattering peak at 557 nm). Accordingly, a dual-mode ratiometric optical sensing platform is constructed for the quantitative detection of PFOA. Download: Download high-res image (97KB) Download: Download full-size image