Efficient Online TurboFlow Method for Simultaneous Determination of 60 Emerging Per- and Polyfluoroalkyl Substances in Milk

Emerging perfluoroalkyl and polyfluoroalkyl substances (PFASs) have received much attention in recent years. Milk has usually low concentrations of PFASs, but it remains an important PFAS exposure route due to its high consumption. In this study, a method for simultaneous determination of 60 PFASs in milk was developed by online TurboFlow liquid chromatography-tandem mass spectrometry. A pH-dependent cold-induced liquid-liquid extraction was developed for precleanup and enrichment. Method quantification limits ranged from 0.003 to 0.500 ng/mL. For PFASs without corresponding isotope-labeled internal standards, Tanimoto coefficient and logP were introduced for the selection of internal standards. The matrix spiked recoveries ranged from 47 to 190%. The method was applied for PFAS analysis in 35 milk samples. PFBS, perfluorohexanesulfonic acid, perfluorooctanesulfonic acid, PFNS, PFPeA, perfluorooctanoic acid, PFNA, and 6:2 FTS were detected. The developed online TurboFlow method was simple, reliable, efficient, and applicable for trace analysis of PFASs in milk.