QUANTIFICATION OF 30 PER- AND POLYFLUOROALKYL SUBSTANCES (PFASS) IN FRUITS AND VEGETABLES

Introduction: Per- and polyfluoroalkyl substances (PFASs) are persistent chemicals with widespread environmental distribution [1]. The European Food Safety Authority (EFSA) identifies fish, fruits and eggs as major sources of human exposure, with PFOA in fruits and vegetables being significant [2]. While no maximum levels for PFASs in fruits and vegetables have been established, Recommendation 2022/1431/EU suggests limits of quantification (LOQs) and indicative levels for four PFASs evaluated by EFSA (PFOS, PFOA, PFNA, PFHxS; EFSA- 4). For fruits and vegetables, the proposed LOQs are ≤0.002 μg/kg for PFOS, ≤0.001 μg/kg for PFOA and PFNA, and ≤0.004 μg/kg for PFHxS [3]. A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for 30 different PFASs. The possibility of grouping different fruits and vegetables matrices was evaluated and the feasibility of meeting the proposed LOQs and indicative levels was assessed.
Materials and Methods: Beetroot, apple, strawberry, lamb's lettuce, olive, and potato were analyzed. Homogenized samples (10 g) were extracted using water, acetonitrile and hydrochloric acid. The resulting extract was evaporated and reconstituted in ammonium acetate. The sample clean-up was performed by solid-phase extraction (SPE). Quantification was carried out on an LC-MS/MS instrument. Validation followed EURL guidelines [4], including the parameters LOQ, accuracy, reproducibility, and recovery assessment.

Results: Quantification of the EFSA-4 at proposed indicative levels was achieved for most samples, except PFHxS in beetroot and olive and PFOS in olive. The proposed LOQ was achievable for PFNA across all samples. Additionally, the proposed LOQ of 0.002 μg/kg for PFOS was met in apples and lamb’s lettuce. The LOQ of PFOA was met for the matrix beetroot and strawberry. Two matrix groups were established: group I for fruits and vegetables with high acid and/or water content, and group II for roots and tubers. The method could not be fully validated for all PFASs, primarily due to
accuracy issues attributed to the absence of suitable internal standards.
Discussion and Conclusion: The analyzed fruits and vegetable samples demonstrates that the quantification at levels as low as 0,001 μg/kg is feasible for certain matrices and PFASs using the developed method. Fruits and vegetables with high fat content may require further sample clean-up to achieve the LOQs proposed by  Recommendation (EU) 2022/1431. Moreover, finding a blank matrix at the concentration range of the recommended LOQs for validation remains a significant
challenge.