Updates on the Use of TOF for PFAS Investigations – Where does it fit in? - PowerPoint Presentation

1. Updates on the Use of TOF for PFAS Investigations – Where does it fit in?Charles NeslundScientific Officer and PFAS Practice LeaderEurofins Environment Testing America

2. 2The General Classes of Per- and Polyfluoroalkyl Substances (PFAS)2Fluorotelomers:SulfonatesCarboxylatesAlcoholsPerfluoroalkyl acidsCarboxylatesSulfonatesSource: ITRC Naming Conventions and PhysicalChemical Properties fact sheetFluoropolymersPerfluoropolyethers (PFPE)Side-chain fluorinated polymers

3. Current Analysis Climate3Current methods for LCMSMSUSEPA 533USEPA 537.1ASTM D7979SW846 method 8327Individual laboratory “537 Mod”/Isotope DilutionLargest of these options are method(s) that are limited to only 40+ compoundsMight add in analysis for fluorotelomer alcohols

4. Current Analysis Climate4Need for screening method – For total FluorideBetter risk assessment tool for true “impact” in the environmentScreening method for narrowing focus of target compound approachWhat are the options?TOP AssayPIGE (particle induced gamma-ray emission spectroscopy)XPS (x-ray photoelectron spectroscopy)TOF (total organic fluorine)

5. 5Total Oxidizable Precursors - TOPConcept is to analyze a sample for perfluoroalkyl carboxylic acids (PFCA) and perfluoroalkyl sulfonic acids (PFSA) and any identified precursors . Then subject a second aliquot of the sample to relatively harsh oxidative conditions. Analyze the oxidized sample for the same perfluoroalkyl acids and precursors. Expect to see; a. Reduction or elimination of the precursors b. Increase in concentrations of perfluoroalkyl acids

6. 6TOP Assay ResultsCompoundPre-OxPost-OxDifferencePFBAND98 ng/l98 ng/lPFPeAND87 ng/l87 ng/lPFHxA5 ng/l61 ng/l56 ng/l6:2 FTS100 ng/lND- 100 ng/lPFHpA11 ng/l32 ng/l21 ng/lPFOA7 ng/l26 ng/l19 ng/lPFOS56 ng/l52 ng/l- 4 ng/l8:2 FTS26 ng/lND- 26 ng/lPFNAND5 ng/l5 ng/l

7. 7Marriage of TOX and ICSample (or treated sample) is combusted in a furnace at 900°C – 1100°CEffluent collected in buffer and injected into ion chromatograph (IC)Quantify fluorine (as fluoride) contentCompare ratio of total (or extractable) fluorine to total PFASTotal Organic FluorineTotal Organic Fluorine (TOF) - Combustion Ion Chromatography (CIC)

8. Total Organic Fluorine Analysis in Water8Methods available or being proposedDIN EN ISO 9562:2004 Water quality — Determination of adsorbable organically bound halogens (AOX)ASTM D19.06 – WK68866 Determination of Adsorbable Organic Fluorine in Waters and Waste Waters by adsorption on Activated Carbon followed by Combustion Ion Chromatography DefinitionsAdsorbable Organic Fluoride – AOF (Activated Charcoal method)Extractable Organic Fluoride – EOF (WAX SPE sample preparation method)

9. Total Organic Fluorine Analysis in Water9Adsorbable Org. F (AOF)Sample Prep100mls sample pass thru activated charcoal bed(s)Final wash with nitrate solution to remove inorganic fluorideCombustion of Charcoal into CIC to measure F- by ICSample Prep100mls sample pass thru weak anion exchange (WAX) SPE Elute PFAS with methanolConcentrate methanol to final 1mLCombustion of extracted sample into CIC to measure F- by ICExtractable Org. F (EOF)Total Org. F (TOF)Sample Prep (water samples)No Sample PrepDirect injection of aqueous sample into CIC system to measure both Inorganic F- and Organic F- simultaneouslyCourtesy of Dr. Jayesh Ghandi - Metrohm

10. Adsorbable Organic Fluoride (AOF)10Currently Proposed ASTM Method (WK 68866)Currently Proposed DIN committee NA 119-01-03-01-12Basics of method100mls of water sample is passed through vertically aligned two carbon cartridgesOrganic compounds (PFAS) are adsorbed on carbon bedFinal rinsing is performed with Potassium Nitrate to remove inorganic Fluoride (interference)Carbon is then combusted with CICCourtesy of Dr. Jayesh Ghandi - Metrohm

11. AOF Data using 50 mls of Water11Sample ID% recovery, AOFPFOS - 173.3PFOS - 288.56:2 FTS-1106.16:2 FTS-2109.3NEtFOSAA -186.8NEtFOSAA -280.6PFOA -195PFOA -284.5FBA - 197.6FBA - 2100.5PFBA -158.4PFBA -267.830ppb MIX-169.130ppb MIX-267.930ppb+KHP -152.430ppb+KHP -253.7Average80.7Note: When High TOC value samples were subjected to 6 carbon beds in series, PFAS recovery is ~79%Courtesy of Dr. Jayesh Ghandi - Metrohm

12. Total Organic Fluorine Analysis of Solids12Adsorbable Org. F (AOF)Sample Prep100mls sample pass thru activated charcoal bed(s)Final wash with nitrate solution to remove inorganic fluorideCombustion of Charcoal into CIC to measure F- by ICSample PrepExtract solid sample with a methanolic solutionConcentrate methanol to final 1mL or lessCombustion of extracted sample into CIC to measure F- by ICExtractable Org. F (EOF)Total Org. F (TOF)Sample Prep For non-soil solids, grind or pulverize sampleFor soil, evaluate granularityDirect combustion of solid sample into CIC system to measure both Inorganic F- and Organic F- simultaneously

13. 13Total Organic Fluorine AnalysisOxidative pyrohydrolytic combustionHandling of the sample prior to fluoride determination determines result evaluatedEOF – Extractable Organic FluorineAOF – Adsorbable Organic FluorineExample for Solids AnalysisTotal Organic Fluorine (TOF) 410 mg F/kg Extractable Organic Fluorine (EOF) 390 mg F/kgLC-MS/MS ƩPFAS (n=28) 120 mg/kg

14. 14PFAS Percent Fluorine

15. 15PFAS Percent Fluorine

16. Total Organic Fluorine Analysis 16SummaryMany things to be learned about the application of CICHow is inorganic fluoride being managed? Or is it?What “selectivity” does the sample preparation apply to the fluoride determinationAre multiple fluoride determinations needed to differentiate inorganic vs organicNeed to agree on definition of AOF vs EOF and relationship to TOF and TF

17. Thank You17Charles NeslundCharles.Neslund@Eurofinset.com717-799-0439