Rapid quantification of per- and polyfluoroalkyl substances (PFAS) in complex wastewater matrices via online...

Expanding monitoring requirements for per- and polyfluoroalkyl substances (PFAS) in water systems require high-throughput analytical methods capable of processing large numbers of environmental samples. These needs have intensified following the Final National Primary Drinking Water Regulation established by the United States Environmental Protection Agency. Conventional PFAS extraction and workflow typically require multistep procedures exceeding six hours and large sample volumes (up to 500 mL), limiting laboratory throughput. This study presents a rapid online solid-phase extraction liquid chromatography mass spectrometry (SPE-LC-MS/MS) method for the quantification of 37 PFAS aligned with EPA Method 1633. The method requires minimal sample preparation consisting of centrifugation, filtration and five-fold dilution, resulting in a final analyzed volume of 2 mL. Online SPE using a weak anion exchange (WAX) sorbent coupled with LC-MS/MS analysis on a pentafluorophenyl (PFP) column enabled a total analysis time of 30 min per sample. Validation demonstrated linearity, precision, and accuracy, with method detection limits as low as 1.74 ng/L for PFOA and 3.65 ng/L for PFOS. Application to municipal wastewater samples from Miami-Dade, FL, including influents, effluents, and septage, indicated short-chain PFAS prevalence. PFBA (77-1908 ng/L) was detected in all samples. Seasonal trends showed significantly higher concentrations in the efluent during the wet season (∑₃₇PFAS = 467 ng/L dry and 1251 ng/L wet). Removal efficiency varied by season: during the dry season, only PFPeA and PFHpA showed measurable removal, whereas compounds such as 5:3 FTCA, N-MeFOSE, and PFDS were completely removed in the wet season, likely due to precursor transformation under aerated conditions.