PFAS 2018: Understanding PFAS Analysis and Reporting

Transcription

1 PAS 2018: Understanding PAS Analysis and Reporting

2 When you think PAS, think 2

3 When you think PAS, think 3

4 PAS Target Compounds Hydrophobic Perfluorooctanoic Acid (POA) Teflon Hydrophilic Hydrophobic Perfluorooctanesulfonic Acid (POS) Scotchguard Hydrophilic Perfluorobutanoic Acid (PBA) Perfluorobutanesulfonic Acid (PBS) Perfluorononanoic Acid (PNA) 4

5 PAS Precursor Compounds 6:2 luorotelomersulfonic Acid (6:2 TS) Perfluorooctanesulfonamide (POSA) CH 3 8:2 luorotelomer Alcohol (8:2 TOH) N-Methyl Perfluorooctanesulfonamide (MeOSA) H N-Ethylperfluorooctanesulfonamidoacetic Acid (EtOSAA) N-Methylperfluorooctanesulfonamidoethanol (MeOSE) 5

6 PAS Replacement Compounds H 2,3,3,3-Tetrafluoro-2-(heptafluoropropoxy)propanoic acid (RD-902) - GenX Heptafluoropropyl-1,2,2,2-tetrafluoroethyl ether (E1) 9-Chlorohexadecafluoro-3-oxanonane-1-sulfonate (53B major) 11-Chlororeicosafluoro-3-oxaundecane-1-sulfonic Acid (53B minor) Dodecafluoro-3H-4,8-dioxanoate (ADONA) 6

7 Why do we care? 7

8 Toxicity Animals: Int. J. Hyg. Env. Health. 2017, 220, Humans: Environmental Health Perspectives 2014, 122, The range of guideline limits established is related to: interspecies differences in the available studies. difference in half-lives between animals and humans. Humans have higher internal exposures than animals. Associations between low dose exposures and: development and immune responses in children. fat metabolism in adults.

9 Analytical Methods and Reporting

10 Method Summary: Water methods based on USEPA SPE weak anion exchange extraction - LC/MS/MS Soil methods based on ASTM D ph adjusted aqueous leach/spe weak anion exchange extraction - LC/MS/MS Industry accepted best practices: - LC/MS/MS - Minimum 2 MRM transitions where possible - Isotope Dilution required for quantitation - No Blank correction 10

11 Analytical Methods 11

12 Turbidity or samples containing sediment Do NOT filter. Absorption to filters. Centrifuge, or allow sample to settle, prior to sampling supernatant. or low levels, where whole bottle is extracted, becomes a non-issue (may introduce a high bias). PAS iltered (ng/l) Centrifuged (ng/l) POS

13 Trizma Preservative TRIS: tris(hydroxymethyl)aminomethane TRIZMA: 2-Amino-2-(hydroxymethyl)-1,3-propanediol Purpose: To buffer the samples (ph 7), remove free chlorine in chlorinated finished waters and prevent microbial degradation. [According to reference method EPA 537] PAS are considered chemically, thermally and biologically stable, and resist typical environmental degradation processes. Microbes can degrade precursor molecules, making more POS / POA Preservative added: 5g/L Should it only apply to chlorinated water supplies? YES Alternative Preservation: An alternative to Trizma (if the clients do not receive bottles from Maxxam) is Sodium Thiosulfate which is also a chlorine neutralizer. Shoemaker, et. al.: Development of a U.S. EPA Drinking Water Method for the Analysis of Selected Perfluoroalkyl Acids by Solid-Phase Extraction and LC-MS-MS. J. Chrom. Sci., Vol. 47, pp (2009) 13

14 Important Considerations: Branched vs. Linear Isomers When interpreting POS data, it is important to understand if it is being quantified as the linear or branched chain isomers Technical POS is a mixture of linear and branched chain POS isomers; Linear POS is typically pure POS Linear Isomer POS Branched Isomer (P6MHpS) Isomer Wellington 1 luka 2 Sigma-Aldrich/ Normal (linear) Monomethyl Isopropyl Alpha T-Butyl Dimethyl Total Branched Lot #TPOS0405: Wellington Laboratories, Guelph, ON, Canada 2 Batch # : Sigma-Aldrich/luka, Buchs, Switzerland 14

15 Measurement Uncertainty and the Value of Isotope Dilution

16 Measurement Uncertainty Definition A parameter associated with the result of the measurement, that characterizes the dispersion of the values that could be reasonably attributed to the measurand.* * ISO Guide to the Expression of Uncertainty in Measurement A value that gives an idea of variability within a set of measurements that is specific to a sample or group of samples. ±value specific to the result 16

17 Interpretation of Low Level Data POS in Soil by LC/MS/MS Variability in analytical results increases as concentrations approach the limits of detection or the upper end of the system s linear range. MDL (LOD) ~ 3 x S.D. RDL (LOQ) ~ 3 x LOD or ~ 10 x S.D What this means is that the level of confidence in the value reported at or above the RDL (LOQ) is much higher than the level of confidence reported at the MDL (LOD) 17

18 POS Laboratory MU MDL RL Low Medium High Concentration (ug/l) Water MU (%) 129% 31% 23% 23% 23% Range (ug/l) "0.000" Concentration (ug/kg) Soil MU (%) 154% 30% 25% 23% 23% Range (ug/g) "0.00"

19 Isotope Dilution LC/MS/MS IDMS provides greater accuracy than other calibration methods because it compensates for any matrix effects that may suppress recovery of the parameters being measured. Simply put the recovery of the labeled compound, which is not naturally present in the sample, is an exact representation of the recovery of the native compound which is present in the sample Ideal is to have as many isotopically labelled analogues as possible 20

20 Total Oxidizable Precursors

21 PAS Precursors PAS such as POA and POS are directly released into the environment PAS precursor compounds are also released along with POS and POA. The precursors are themselves PAS. Target PAS and selected precursors are monitored in the environment for remedial action O S H 2 N O POSA Problem Statement Pool of potential precursors is large and generally unknown PAS Dark Matter Precursors can be transformed, through biological and environmental processes, to target PAS of interest such as POS/POA Overlooking precursor pool may lead to underestimates of target PAS of interest HO O Natural Processes Requirement A method to estimate the potential magnitude of the precursor pool POA 23

22 TOPs Assay (1) Before TOP Assay Sample Oxidation Quantify targets and precursors LC/MS/MS Analysis PAS Precursor H H H H O 8:2 luorotelomer sulfonate (C 10 total, C 8 containing ) S O O - After TOP Assay Quantify targets and precursors HO O HO O Reacted Sample LC/MS/MS Analysis 1 Houtz, E.. and Sedlak, D.L. (2012). Environ. Sci. Technol., 46, Perfluorooctanoic acid (C 8 ) O HO Perfluoroheptanoic acid (C 7 ) Perfluorohexanoic acid (C 6 ) O HO Perfluorobutanoic acid (C 4 ) 24

23 Concentration (µg/l) Concentration (µg/l) TOPs Assay (Groundwater) 140 Before Top Assay C After TOP Assay 100 C C C 7 C 8 C 4 C 6 C Before TOP Assay C Perfluorooctane sulfona Precursors Carboxylic acids Sulfonates 25

24 Considerations Method limited only to compounds that are oxidizable by the Assay the precursor pool may be underestimated if not all precursors are transformed/oxidized Not all of the PAS that are produced during the TOP assay necessarily originate from only the 9 precursors that are monitored pool of precursors is large There could be numerous target PAS that are produced beyond the 16 that are currently monitored It is unknown if all precursors are fully oxidized by the TOP assay How representative is the TOP assay of the transformations that would occur naturally? - Timescale 26

25 What the TOPs Assay Offers Quick and simple method of oxidation that can be performed on soil and water Provides estimate of target PAS increase that could occur at a contaminated site Potential indication of which precursors are being oxidized Assay will become more informative as more PAS targets and precursors of concern are added to the analysis list Assay report provides concentrations of 25 PAS before and after oxidation 27

26 Regulatory Limits and Laboratory Reporting Limits

27 Regulatory Limits What were once guidance limits are being promulgated as regulated standards, particularly in drinking water BC only jurisdiction in Canada (to date) to legislate PAS regulatory limits POS, POA and PBS regulated in water POS, PBS regulated in soil All other provinces and many US states have Health Advisories or guidelines but this is changing 29

28 Regulatory Limits (1) (Water) Jurisdiction POA (μg/l) POS (μg/l) PBA (μg/l) PBS (μg/l) PHxS (μg/l) PPeA (μg/l) PHxA (μg/l) PHpA (μg/l) PNA (μg/l) GenX (ug/l) Drinking Water Health Canada (2) Screening Value N/V British Columbia BC CSR N/V 80 N/V N/V N/V N/V N/V N/V U.S.A - EPA Health Advisory N/V N/V N/V N/V N/V N/V N/V N/V U.S.A. Minnesota HBV N/V N/V N/V N/V N/V U.S.A. New Jersey MCL N/V N/V N/V N/V N/V N/V N/V U.S.A. N. Carolina IMAC 2 N/V N/V N/V N/V N/V N/V N/V N/V 0.14 Europe UK HBV N/V N/V N/V N/V N/V N/V N/V N/V Australia HBV N/V N/V 0.07 N/V N/V N/V N/V N/V (1) Sources: ITRC PAS Regulations, Guidance and Advisories act Sheet (June 2018) (2) Protection of Human Health - [POS]/SV POS + [POA]/SV POA 1 (3) Highlighted values have not yet been promulgated 30

29 Reporting: RDL vs. MDL Compound RDL (μg/l) Water Soil Tissue MDL (μg/l) RDL (low) (μg/l) RDL (μg/kg) MDL (μg/kg) RDL (ng/g) Perfluorobutanoic Acid (PBA) Perfluorobutanesulfonic Acid (PBS) Perfluoropentanoic Acid (PPA) Perfluorohexanoic Acid (PHxA) Perfluorohexanesulfonic Acid (PHxS) Perfluoroheptanoic Acid (PHpA) Perfluoroheptanesulfonic Acid (PHpS) Perfluorooctanoic Acid (POA) Perfluorooctanesulfonic Acid (POS) Perfluorononanoic Acid (PNA) Perfluorodecanoic Acid (PDA) Perfluorodecanesulfonic Acid (PDS) Perfluoroundecanoic Acid (PUdA) Perfluorododecanoic Acid (PDoA) Perfluorotridecanoic Acid (PTrDA) MDL (ng/g) Perfluorotetradecanoic Acid (PTeDA)

30 Recent References Interstate Technology & Regulatory Council (ITRC) act Sheets: National Groundwater Association: accepting-public-comments-on-ngwa%e2%80%99s- Groundwater-and-PAS-State-of-Knowledge-and- Practice.aspx 33

31 Acknowledgements Analytical Method Development and Operations Adam Robinson Sin Chii Chia, MSc Colm McNamara Project Management Melissa Di Grazia, BSc Stephanie Pollen, BSc TOPs Assay Validation Pat Benvenuto, PhD Heather Lord, PhD Christopher Atkinson, BSc Dany Marqass Consuelo Perez, MSc 34

32 Contacts Heather Lord, PhD Manager Environmental R&D (905) Stephanie Pollen, BSc Project Manager Ultra Trace Analysis (905) Adam Robinson Manager LC and LC/MS/MS Methods (905) ext Terry Obal, PhD, CChem Chief Science Advisor (905)

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