Reliable and sensitive ultra-short chain per- and polyfluorinated alkyl substances (PFAS) analysis in food: a polar reverse-phase chromatography approach.

Food contamination by per- and polyfluoroalkyl substances (PFAS), especially ultra-short-chain (USC) compounds, poses a growing concern due to their environmental persistence and potential health risks. Despite the developing regulatory framework, analytical challenges persist in quantifying polar USC-PFAS in complex content food matrices. This study presents the development and validation of a novel high-performance liquid chromatography coupled to a tandem mass spectrometer (HPLC-MS/MS) method for the accurate determination of USC-PFAS (carbon chain length from one to four, C1-C4) in tomato-based products (i.e. concentrate, puree, and pulp), that, due to their high water content, are prone to USC-PFAS contamination. Leveraging a polar analytical column and a delay column, the method effectively mitigates system-related interferences, especially for trifluoroacetic acid (TFA) and achieves enhanced retention and sensitivity. Target compounds included Difluoroacetic acid (DFA), TFA, Perfluoropropanoic acid (PFPrA), Perfluorobutanoic acid (PFBA), Perfluoromethanesulfonic acid (PFMeS), Perfluoroethanesulfonic acid (PFEtS), Perfluoropropanesulfonic acid (PFPrS), and Perfluorobutanesulfonic acid (PFBS). The quantification based on isotope dilution ensures high accuracy and precision. The method demonstrated excellent linearity (R² ≥ 0.99), recoveries within 65-135 %, and low relative standard deviation (RSD) values (<10 %). PFBA was detected across all tested tomato products, with concentrations ranging from 0.056 to 0.265 µg/kg, indicating potential endogenous contamination potentially linked to processing concentration effects. This study fills a critical methodological gap, offering a robust analytical tool for USC-PFAS monitoring in complex food matrices, and supporting improved food safety regulation.