Application of VUV/Sulfite Defluorination System for the Simple Detection of Perfluoroalkyl Substances

This study investigated the defluorination of PFOA and PFOS using a vacuum ultraviolet (VUV)/sulfite system, and evaluated its potential application in quantifying individual perfluoroalkyl substances (PFAS). Results showed that 81.9% and 87.5% defluorination of PFOA and PFOS were achieved after 120 min of photoreaction under conditions of pH 12 and 20 mM of sulfite. Higher pH and sulfite dosage facilitated the reaction, while competing ions could suppress the defluorination efficiency. Based on the optimized defluorination conditions for individual PFAS, the potential of fluoride release amount, as an indirect quantification indicator, was further assessed. A strong linearity between the fluoride release and initial PFAS concentration (R² > 0.999) was observed in the PFAS concentration range of 2-100 μM, and such linearity was also shown in the presence of sediment leachates. This correlation enabled the estimation of individual PFAS concentrations by measuring fluoride release after defluorination treatment. The approach was further demonstrated in an adsorption experiment, where calculated distribution coefficients (K_oc) for PFAS-sediment interactions were consistent with previously reported values, supporting the analytical validity of the method under controlled conditions. Overall, this work presents a simple and cost-effective indirect analytical strategy of applying a VUV/sulfite defluorination system for individual PFAS quantitative detection in complex environmental matrices.