An Interlaboratory Validation Study for the assessment of Low Limits of Quantification for PFAS in Foods of Plant Origin

Per- and polyfluoroalkyl substances (PFAS) extensively contaminate the environment and can enter the food chain. Fruits and vegetables represent a significant, yet under-regulated, human exposure pathway due to the uptake of PFAS by plants from contaminated soil/water. PFAS exposure is linked to adverse health effects. EFSA has established a strict group tolerable weekly intake of 4.4 ng/kg bw /week for PFOA, PFOS, PFHxS, and PFNA, leading the EU to introduce specific regulations. However, EU maximum levels in plant-derived foods are lacking because the achievability of limits of quantification (LOQ) of 0.001 μg/kg poses significant analytical challenges. This study presents the results of an extensive interlaboratory validation study among European laboratories using various triple quadrupoles and high-resolution mass spectrometers. The aim was to assess method robustness and achievability of analytical LOQs required by EU guidance with a focus on the EFSA-4 PFAS. The interlaboratory validation study involved 240 food extracts prepared in two different laboratories by two operators each. The quantification was performed across four laboratories and seven analytical setups. The validated method showed robustness, with an apparent recovery between 65 % and 135 % , uncertainty and RSD below 25 % , and consistency with current EU guidelines. The application of internal 13 C-labeled standards and the use of very sensitive mass spectrometers proved to be a critical factor in achieving low LOQs. • Ultra-trace PFAS in plant foods shown achievable LOQs down to 0.001 μg/kg. • Robust method validated across 240 extracts, 6 matrices, 4 labs, and 7 LC–MS setups. • 87% of PFAS validated at ≤0.100 μg/kg, with >99% of them achieving LOQs ≤0.050 μg/kg. • Low LOQs driven by workflow control and 13 C-labeled standards, not instrument power. • Clear roadmap for EU monitoring: TQ for EFSA-4, HRMS for interferences and screening.