Analytical challenges associated with compliance testing of the PFAS parameters in the EU Drinking Water Directive

www.tzw.de Analytical challenges associated with compliance testing of the PFAS parameters in the EU Drinking Water Directive Frank Thomas Lange WRc, PFAS and Emerging Contaminant Forum 2025 May 22, 2025 Different kinds of analytical approaches needed PFC Vorläufersubstanz en Source: precursors Sink: terminal degradation products e.g. fluorosurfactants in AFFF groundwater degradation processes transport of degradation products PFCAs, PFSAs, some additional PFAS e.g. fluorochemicals in paper-fiber biosolids drinking water PFAS parameters in Directive (EU) 2020/2184 PFAS PFAS Total 0.50 µg/l Sum of PFAS 0.10 µg/l limit of quantification: ≤ 30 % of parametric value Article 13, paragraph 7 By 12 January 2024, the Commission shall establish technical guidelines regarding methods of analysis for monitoring of perand polyfluoroalkyl substances under the parameters ‘PFAS Total’ and ‘Sum of PFAS’, including detection limits, parametric values and frequency of sampling. 20 compounds (C4-C13) 10 PFCAs, 10 PFSAs uncertainty of measurement: ≤ 50 % Support for the EU Commission, DG ENV Consortium Service contract No. 090202/2023/890359/SER/ENV.C.2 Service contract No. 090202/2023/890359/SER/ENV.C.2 Support for the EU Commission, technical part Task 1 TZW (lead)/ORU Technical assessment of targeted (specific) methods for PFAS Task 2 ORU (lead)/TZW/UCPH Technical assessment of non-targeted and non-specific methods for PFAS Sum of PFAS PFAS Total Directive (EU) 2020/2184 - Sum of PFAS NotesUnitParametric value Parameter ‘Sum of PFAS’ means the sum of perand polyfluoroalkyl substances considered a concern as regards water intended for human consumption listed in point 3 of Part B of Annex III. This is a subset of ‘PFAS Total’ substances that contain a perfluoroalkyl moiety with three or more carbons (i.e. –CnF2n–, n ≥ 3) or a perfluoroalkylether moiety with two or more carbons (i. e. –CnF2nOCmF2m–, n and m ≥ 1). µg/l0.10Sum of PFAS 20 compounds (C4-C13) - 10 PFCAs - 10 PFSAs PFBA C4, n = 3 PFBS C4, n= 4 F F F F F F FO OH F F F F F F F S F F O O OH (Missing) relevance of PFAA ≥ C10 no relevance ≥ C10 U. Borchers et al., energie | wasser-praxis 09/2022, p. 64-71 carbonic acids sulfonic acids average concentration in µg/L PFAS: 20 according to DWD Period: 2015-2022 Matrix: drinking water Number 1119 Red frame: EFSA-PFAS Rating of targeted methods for Sum of PFAS „big points“ (max. 20 out of 100 points each) number of assessed PFAS selectivity (risk for false positives/negatives) sensitivity (LOQ) uncertainty of measurement pre-screening criteria Only standard methods or drafts Designed for drinking water matrix Include at least half of PFAS20 Targeted analysis by LC-MS/MS for Sum of PFAS EN 17892 Part B (offline/ online SPE) EN 17892 Part A (direct injection) ISO 21675US EPA 533 US EPA 537.1 DIN 38407-42 20222022201920192018 (rev. 2020) 2011year >80>8050-8050-8050-80<50 point range (max. points = 100) acceptableacceptabletentatively acceptable tentatively acceptable tentatively acceptable unacceptableevaluation Recommendation: EN 17892:2024-8 (part A or B) for determination of Sum of PFAS Application of TOP assay to drinking water? Pelch K.E. et al. (2023) STOTEN, 876, 162978 • Use of mass concentrations instead of molar concentrations (mass loss not taken into account) • TFA as a reaction endpoint not measured • Many concentrations close to LOQ, LOQpre < LOQpost “Results were inconclusive on the utility of the TOP Assay for monitoring drinking water.” ∑ PFAS 21 pre (ng/L) ∑ PFAS 21 post (ng/L) ΔPFAS Change (%) ∑ PFCA 11 pre (ng/L) ∑ PFCA 11 post (ng/L) ΔPFCA 11 Change (%) Sample 1 15.3 28.2 12.9 84.3 0 12.5 12.5 Sample 2 52.1 58.8 6.7 12.9 46 52.5 6.5 14.1 Sample 3 153.1 168.4 15.3 10.0 65 82.5 17.5 26.9 Sample 4 7920 7618.5 -301.5 -3.8 5400 5094 -306.5 -5.7 Sample 5 4459 4275.5 -183.5 -4.1 4200 4094 -106.5 -2.5 Sample 6 13 12 -1 -7.7 13 12 -1 -7.7 Sample 7 12.5 0-12.5 -100.0 12.5 0 -12.5 -100.0 Sample 8 7.4 0-7.4 -100.0 0 0 0 Sample 9 6.1 6 -0.1 -1.6 0 0.7 0.7 Sample 10 0 0 00 0 0 Sample 11 0 0 00 0 0 Utility of TOP assay for PFAS Total analysis? •TOP assay reveals the presence of unknown precursors. •Low PFAS concentrations in drinking water hampers its application. •TOP assay results in a mass concentration of reaction products (PFCA, further products). •Mass concentration of reaction products ≤ mass concentration of PFAS in the native sample. •For testing compliance with the PFAS Total parametric value (0.5 µg/L) an additional convention is needed for reporting: •Result: [PFAS TotalTOP]= Σ product mass concentrations EOF: different fluorine fractions in a sample TF = IF + OF OF = EOF + NEOF TF IF OF EOF NEOF TF IF e.g. fluoride, fluoro complexes of Al, BF4-, PF6OF EOF NEOF ∑nF(known PFAS) Total fluorine Inorganic fluorine Organically bound fluorine Extractable organically bound fluorine Non-extractable organically bound fluorine EOF: Workflow of sample preparation EOF Y. Miyake et al. (2007) Adsorption weak anion exchanger Clean-up for F-removal 0.01% NH4OH in MeOH Elution e.g. with MeOH, 0.1% NH4OH in MeOH Combustion-Ion Chromatography (CIC) Utility of EOF-CIC for PFAS Total analysis •EOF has a low selectivity, i.e. broad analytical window: positive from the viewpoint of precautionary principle •However, it also discriminates substances during sample preparation, e.g. ultrashort-chain PFAS, such as TFA. •For EOF it is still unknown, how many drinking waters would exceed the parametric value of 0.5 µg/L. •For testing compliance with parametric value (0.5 µg/L) an additional convention is needed: PFOA-equivalents (345 ng/L F ≙500 ng/L PFOA) •Result: [PFAS TotalEOF-CIC PFOAeq] HRMS for NTS: Feature prioritization / PFAS identification Bugsel et al. 2023 TrEAC 40, e00216 Utility of suspect target screening / NT analysis by LC-HRMS for PFAS Total analysis •PFAS are analyzed without prior transformation. •Broad analytical window, determined by sample preparation and the availability of suspect lists •Only ionizable PFAS can be detected. •Confirmation of compound identity depends on confidence levels. •Result dependent on the individual workflow •No LC-HRMS standard method available for PFAS in drinking water. •Semi-quantitative: critical for compliance testing •Result: [PFAS TotalHRMS] TFA: the problem child of PFAS Total and it’s entrance pathways into the environment TFATFA (bio-)degradation of pesticide active ingredients → e.g. flufenacet manure (bio-)degradation of pharmaceuticals → e.g. sitagliptin urine industrial emissions primary source secondary source photolysis of blowing agents & refrigerants (e.g. air conditioning) and atmospheric deposition Increasing TFA concentrations in groundwater Albers, C.N. & Sultenfuss, J., Environ. Sci. Technol. Lett. 2024, 11, 10, 1090–1095 TFA concentration dominates PFAS Total Median (all samples) 0.25 µg/L Scheurer & Nödler (2021), Food Chemistry 351, 129304 Parametric value of the EU-DWD: 0.5 µg/L Global 2000: TFA: The forever chemical in drinking water Contact Dr. Frank Thomas Lange Department Water Chemistry / Section Water Chemistry Research Tel.: +49 721 9678-157 [email protected]