Determination of 22 Per- and Polyfluoroalkyl Substances in Surface Water by Solid-Phase Extraction with Ultra-High Performance Liquid Chromatography-Tandem Mass Spectrometry
A robust analytical method was developed for the simultaneous determination of 22 per- and polyfluoroalkyl substances (PFAS) in surface water using ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). To address the loss of particle-bound PFAS, the method incorporates a methanol extraction step for particulate matter retained on filters, followed by combining the extract with the filtrate. Samples were then concentrated and purified using weak anion exchange (WAX) solid-phase extraction (SPE) cartridges. After nitrogen evaporation, the residue was reconstituted in methanol/water (8:2, v/v) and filtered prior to analysis. Quantification was performed using isotope dilution. The method exhibited excellent linearity (R² > 0.995) over a concentration range of 1–250 µg/L. Method detection limits ranged from 0.2 to 0.6 ng/L, and method quantification limits from 0.8 to 2.4 ng/L. Recoveries in blank water and surface water matrices were 85.3%–139% and 76.4%–127%, respectively, with relative standard deviations (RSD, n=6) below 15%. Compared to conventional methods without particulate extraction, this approach significantly improved recovery rates in surface water, effectively eliminating negative bias caused by particle adsorption. The method is sensitive, accurate, and reliable, making it suitable for routine monitoring of PFAS in surface water.