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Navigating the Challenges for the Analysis of PFAS in Environmental Matrices to Meet TRRP Requirements

Providing comprehensive scientific resources to environmental clients worldwide.

Charles Neslund, Technical DirectorTCEQ Environmental Trade Fair, May 16-17, 2017

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• Polyfluorinated Alkyl Substances (PFAS) are a class of compounds that have been in use since the late 1940’s, early 1950’s.

• PFAS consists of both perfluorinated and polyfluorinated compounds

• Perfluorinated – all carbons in the chain are fully bonded to fluorine

• Polyfluorinated – not all carbons in the chain are only bonded to fluorine

Polyfluorinated Compounds

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PFAS compounds have been used in many applications. They have been used as additives in fluoropolymer production and as surfactants for numerous consumer applications;

• Stain resistant coatings for furniture and carpeting• Coatings for fast food wrappers and boxes• Breathable waterproof fabrics• Insecticides• Lubricants• Chromium Plating (mist suppression)


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PFASs were also used in Aqueous Film Forming Foams (AFFF). Developed by 3M and US Navy in the 1960’s. The low surface tension and positive spreading coefficient enabled film formation on top of lighter, less dense fuels.AFFF is a complex, proprietary mix that has been used in large volumes for decades;

- Military - Oil and Gas Industry- Airports - Chemical Manufacturing- Fire Training Installations


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• From mid-60’s to 1976, 3M sole source supplier of AFFF

• Ansul and National Foam became suppliers in 1976• Since 1994, Angus, Chemguard

and Fire Service Plus• Reality is multiple AFFFs

used at most sites


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However, out of these chemistries there are two compounds that have received the most attention;

a. PFOA - was used as a surfactant in the manufacture of fluoropolymers – DuPont

b. PFOS - was the principle component in Scotchgard and AFFF manufactured by 3M – manufacture by 3M has been discontinued since 2002


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Perfluorooctanoic acid (also known as PFOA)MW = 414 amuBP = 189-192 °CDensity = 1.8 grams/ml

PFAS

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Perfluorooctane sulfonic acid (also known as PFOS)MW = 500 amuBP = 133 °C at 6 torr

PFAS

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• The fluorine substitution gives this class of compounds unique characteristics

• Contain a hydrophobic, fully fluorinated carbon chain

• Also contains a hydrophilic functional group

• Acids have low pKa’s and therefore at environmental pHs are soluble to moderately water soluble

PFAS

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There are several chemistries that are being looked at;

• perfluorinated carboxylic acids

• perfluorinated sulfonic acids/sulfonates

• polyfluorinated telomer sulfonates

• perfluorinated sulfonamides

• fluorotelomer alcohols


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Perfluorobutanoic acid PerfluorobutanesulfonatePerfluoropentanoic acid PerfluorohexansulfonatePerfluorohexanoic acid PerfluoroheptanesulfonatePerfluorheptanoic acid PerfluorooctanesulfonatePerfluorooctanoic acid PerfluorodecanesulfonatePerfluorononanoic acid PerfluorooctanesulfonomidePerfluorodecanoic acid Methylperfluoro-1-octanesulfonamidePerfluoroundecanoic acid Ethylperfluoro-1-octanesulfonamidePerfluorododecanoic acid 4:2 Fluorotelomer sulfonatePerfluorotridecanoic acid 6:2 Fluorotelomer sulfonatePerfluorotetradecanoic acid 8:2 Fluorotelomer sulfonatePerfluorohexadecanoic acid 10:2 Fluorotelomer sulfonateN-methylperfluoro-1-octanesulfonamidoacetic acidN-ethylperfluoro-1-octanesulfonamidoacetic acid2-(N-methylperfluoro-1-octanesulfamido)-ethanol2-(N-ethylperfluoro-1-octanesulfamido)-ethanol


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• PFASs are generally chemically and biologically stable. Resist typical environmental degradation processes

• PFASs bioaccumulate and by some estimates are present in blood serum of up to 98% of wildlife

• PFOS added to Stockholm Convention list of Persistent Organic Pollutants

• Growing library of toxicological and eco-toxicological studies so impacts are becoming better understood. Reference dose values for many compounds still an issue.


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• EPA Office of Water established Health Advisory Levels*PFOS = 0.07 ug/l PFOA = 0.07 ug/l

• Minnesota one of few states with any regulatory action limits

PFOS = 0.3 ug/l PFBS = 7 ug/lPFOA = 0.3 ug/l PFBA = 7 ug/l

• New Jersey preliminary health based guidance**PFOS = 0.2 ug/l PFNA = 0.01 ug/lPFOA = 0.04 ug/l (** 0.014 ug/l)

• Vermont Groundwater Enforcement StandardPFOS = 0.02 ug/l PFOA = 0.02 ug/l

• EPA Region 4 levels in soilsPFOS = 6 mg/kg PFOA = 16 mg/kg

Advisory Limits

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* The U.S. Environmental Protection Agency (EPA) is issuing a lifetime drinking water Health Advisory (HA) for PFOA of 0.07 micrograms per liter (μg/L) based on a reference dose (RfD) derived from a developmental toxicity study in mice; the critical effects included reduced ossification in proximal phalanges and accelerated puberty in male pups following exposure during gestation and lactation.EPA Document Number: 822-R-16-005 May 2016

The U.S. Environmental Protection Agency (EPA) is issuing a lifetime drinking water health advisory (HA) for PFOS of 0.07 micrograms per liter (μg/L) based on a reference dose (RfD) derived from a developmental toxicity study in rats; the critical effect was decreased pup body weight following exposure during gestation and lactation.EPA Document Number: 822-R-16-004 May 2016

Advisory Limits - Update

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Tier 1 Groundwater PCLsCompound CAS # Conc ng/lPerfluorooctanoic sulfonic acid 1763-23-1 560

Perfluoroundecanoic acid 2058-94-8 290

Perfluoropentanoic acid 2706-90-3 93

Perfluorohexanoic acid 307-24-4 93

Perfluorododecanoic acid 307-55-1 290

Perfluorooctanoic acid 335-67-1 290

Perfluorodecanoic acid 335-76-2 370

Perfluorodecane sulfonic acid 335-77-3 290

Perfluorohexane sulfonic acid 355-46-4 93

Perfluorobutyric acid 375-22-4 71,000

Perfluorobutane sulfonic acid 375-73-5 34,000

Perfluoroheptanoic acid 375-85-9 560

Perfluorononanoic acid 375-95-1 290

Perfluorotetradecanoic acid 376-06-7 290

Perfluorotridecanoic acid 72629-94-8 290

Perfluorooctane sulfonamide 754-91-6 290

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There is only one EPA “sanctioned” method for the analysis of perfluorinated compounds – EPA Method 537, Version 1.1

• Drinking water method – prescriptive list of compounds

• Uses LC/MS/MS which is the analytical technique of choice

• Has some limitations in the range of compounds that can be accommodated

Analytical Methodology

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• ISO Method 25101: 2009 often referenced, more amenable to surface water and wastewater

• ASTM Methods D7979-15 addresses water and ASTM D7968-14 addresses sludges and soils but have not been subject to an EPA validation

• No established method for soils, so often certify to lab SOP


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• These methods are typically fit for the stated purpose, but may fall short as list of compounds and matrices increases.

• In general, water methods use solid phase extraction (SPE) for the removal of PFASs from aqueous matrix

• Soil methods involve extraction with solvent and/or water mix


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• EPA Method 537 uses an SDVB solid phase extraction cartridge, which is adequate for the compounds listed. Falls short with additional compounds like the C4 and C5 acids.

• EPA 537 uses 3 surrogate compounds and 3 internal standards.

• Calibration is a typical internal standard calibration, which can be impacted by ion suppression observed with some matrices


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Unregulated Contaminant Monitoring Rule

Perfluorinated Compounds (PFCs): EPA Method 537 included as UCMR3 List 1 Contaminants;

Compound MRL ug/lPerfluorooctanesulfonic acid 0.04Perfluoroctanoic acid 0.02Perfluorononanoic acid 0.02Perfluorohexanesulfonic acid 0.03Perfluoroheptanoic acid 0.01Perfluorobutanesulfonic acid 0.09

UCMR3

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• Compounds are selected from the Contaminant Candidate List

• Measures contaminants with no health standards under the Safe Drinking Water Act

• Used to determine whether or not to regulate. Typically requires > 30-40% detects

• Focused on large water supplies (serving >10,000 people)

• Approximately 4% of UCMR3 water samples had PFAS detections above MRLs

UCMR3

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• ASTM D7979-15 avoids extraction by using direct injection

• Use 9 isotopically labeled compounds as surrogates

• Uses external standard calibration

• Covers a much broader list of PFAS compounds – up to 21

• Reporting limits in the 5 ng/l to 25 ng/l range for most compounds


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For Comparison…

Analyte Acronym

WaterReportingLimitsLOQ(ng/L)

SoilReportingLimitsLOQ(ng/g)

Perfluorohexanoicacid PFHxA 2 0.4

Perfluoroheptanoicacid PFHpA 2 0.6

Perfluorooctanoicacid PFOA 2 0.6

Perfluorononanoicacid PFNA 2 0.4

Perfluorodecanoicacid PFDA 2 0.4

Perfluoroundecanoicacid PFUnDA 3 0.6

Perfluorododecanoicacid PFDoA 2 0.6

Perfluorotridecanoicacid PFTrDA 2 0.6

Perfluorotetradecanoicacid PFTeDA 2 0.6

Perfluorobutanesulfonate PFBS 2 0.6

Perfluorohexanesulfonate PFHxS 2 0.6

Perfluoro-octanesulfonate PFOS 6 0.9

8:2fluorotelomersulfonate 8:2FtS 10 0.9

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• For our applications, we are tasked with a broader list of compounds and a wider range of matrices

- Water/wastewater- soil/sediment- tissue

• Use of weak anion exchange for extraction/clean-up• Incorporated the use of 18 isotopically labeled

compounds as surrogates and isotope dilution quantitation


Instrumental Analysis

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• Added in the use of several injection standards for monitoring and comparing instrument vs extraction performance

• Target list of compounds increased to 27 “native” covered by 18 labeled compounds

• As manufacturers provide more labeled analogs, will be a complete isotope dilution technique


Instrumental Analysis

Recent Updates

EPA is releasing a document titled, “Technical Advisory-Laboratory Analysis of Drinking Water Samples for Perfluorooctanoic Acid (PFOA) Using EPA method 537 Rev 1.1.” This advisory describes a processes for laboratories to measure PFOA in a more comprehensive way. The improved technique allows laboratories to more consistently account for isomeric forms of PFOA (linear, the dominant form and branch-chained, the less common form) in the absence of a quantitative analytical standard that includes the various isomers. The approach described in the advisory is more inclusive and more protective. EPA therefore recommends that laboratories use the technique in future analysis.

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• In response to this guidance document acquired technical grade standards of PFOS, PFOA and PFHxS.

• Technical grade standards run with initial calibrations as a qualitative indication of retention of branched isomers.

• Branched summed with linear peak for calculation of PFAS content.


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Total Ion Chromatogram of Technical Grade Standard

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At North American SETAC meeting in Orlando, FL in November of 2016, EPA indicated that they expect to release two draft methods for the analysis of PFAS compounds in non-potable water and soils/sediments by March of 2017.

Update given in March that the process has been delayed and now estimate to be end of May 2017.

Future

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TOP – Total Oxidizable PrecursorsBased on paper authored by Erika Houtz and David Sedlak (ES&T, 2012, 46, 9342-9349)

Concept is to analyze a sample for perfluorinated acids and precursors (such as telomer sulfonates). Then subject a second aliquot of the sample to relatively harsh oxidative conditions. Analyze the oxidized sample for the same perfluorinated acids and precursors. Expect to see;

a. Reduction or elimination of the precursorsb. Increase in concentrations of perfluorinated acids

Future – TOP Analysis

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• The emergence of contaminants like PFAS have increased the need and use of LC/MS/MS in the environmental lab

• What “started out” as an analysis for PFOA and PFOS has rapidly grown to a more expanded list

• As the list of analytes and matrices has expanded it has required labs to modify existing methodologies to achieve desired quality and performance

• Delivery of the anticipated EPA methods could bring about the needed consistency

Summary

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Questions

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