Direct Analysis of Per- and Polyfluoroalkyl Substances (PFAS) in Plasma by Liquid Chromatography Coupled to Mass Spectrometry (LC–MS) for Biomonitoring Purposes

A rapid and direct liquid chromatography–mass spectrometry (LC–MS) method was developed and validated for high-throughput biomonitoring of Per- and Polyfluoroalkyl Substances (PFAS) in human plasma. This approach streamlines the analytical workflow by replacing traditional, labor-intensive solid-phase extraction (SPE) with a simple protein-precipitation step. Twenty-three PFAS (PFBA, PFPeA, PFHxA, PFHpA, PFOA, PFNA, PFDA, PFUnA, PFDoA, HFPO-Da, PFMPA, PFMBA, PFBS, PFPeS, PFHpS, PFOS, ADONA, 4:2 FTS, 6:2 FTS, 8:2 FTS, 9Cl-PF3ONS, 11Cl-PF3OUdS, PFEESA) were monitored. Method detection limits (MDLs) and limits of quantification (LOQs) ranged from 0.01 to 0.39 ng/mL and from 0.04 to 1.2 ng/mL, respectively. Accuracy (bias) and precision (RSD) were below 16% and 10%, respectively, for all PFAS in both intra- and inter-day experiments. Recoveries ranged from 86 to 102%, and matrix effects were estimated as ion suppression below 30% for all analytes. The method was successfully applied to a cohort of 426 Italian citizens who participated on a voluntary basis. Twelve PFAS were detected, with PFOS and PFOA present in 95% of the samples. The mean and median sums of detected PFAS were 7.3 ng/mL (SD 4.6) and 6.2 ng/mL IQR4.4-9.2 , respectively, with a maximum total concentration of 35 ng/mL. PFOS isomers (linear + branched) contributed the most to the total PFAS burden in plasma, reaching a maximum concentration of 25 ng/mL. Overall, this method proved to be a reliable and efficient tool for large-scale biomonitoring studies and provides an important basis for investigating the long-term health implications of PFAS exposure.