Advanced Photothermal Spectroscopy for Trace PFAS Detection

Abstract The widespread industrial and consumer use of per- and polyfluoroalkyl substances (PFAS) has led to their persistent presence in the environment, driven by their robust carbon-fluorine bonds and bioaccumulative properties. This contamination poses serious health and ecological risks, making real-time, selective, and sensitive detection of PFAS critical for effective mitigation. We demonstrate a selective and sensitive detection of vapor-phase PFAS using photothermal cantilever deflection spectroscopy (PCDS), achieving a detection limit of ~30 pg. This method eliminates the need for chemically selective coatings, relying instead on the physisorption of PFAS molecules onto a bi-material microcantilever. By leveraging mid-infrared absorption and monitoring both cantilever bending and resonance frequency, PCDS enables simultaneous chemical identification and mass quantification. The technique demonstrates high selectivity in the mid-infrared fingerprint region and rapid desorption of analytes, offering significant advantages for real-time environmental monitoring and public health protection.