disclaimer - · pdf fileord chris impellitteri ([email protected])...
TRANSCRIPT
Disclaimer
The views expressed in this presentation are those of the individual authors and do not necessarily reflect the views and policies of the US EPA. Mention of trade names or commercial products does not constitute endorsement or recommendation for use
Overview
• What the presentation doesn’t cover:
– Toxicology – Health research – Regulatory Aspects
• What this presentation does cover:
Research to support… • Source/Site characterization and Remediation
– Analytical Methods for non-DW matrices – Sampling and analytical issues
CHEMICALSATPFASSITES….PFOA/PFOSANDSOMUCHMORE!
3
PFASsentertheenvironment…
Photo Courtesy: USEPA, USGS, Artsyltech, West basin, Royer, DuPont
Consumer products use/disposal
Other discharges
Sources
Direct use in the environment
WWTP
Risk Management
Landfill
Voluntary, Institutional, and Regulatory Controls
Environment
Common PFAS Structures
MorePFAS
Backe et al. 2013 ES&T
Perfluoroalkyl Sulfonates
Perfluoroalkyl Carboxylates
Fluorotelomer Sulfonamide Amines
Fluorotelomer Sulfonates
Fluorotelomer Betaines
MorePFASStructures
Sulfonamides
Phosphate esters
Telomer Acids
Phosphinic/phosphonic
F
F
F
F F
F OF
P-OO
OH
n = 4,6,8
F
F
F
F F
FF P
O
RR
n = 2,4,6
R = OH, H
S O
O N CF3(CF2)7
R
CH2CH2COOH
R = methyl, ethyl
C C CF
F
F
F F
FCH2
CF
O
OH
n = 4,6,8
PFASs … More than just PFOA and PFOS
8
PFAS Degradation & Stability: Fluorotelomer alcohol example
The C-F bond is very stable & tends not to degrade under natural conditions.
Consequently, when PFAS degrade, it is usually at/near the non-fluorinated group.
PFAS generally are manufactured with a non-fluorinated terminus group to anchor to intended substrate (e.g., fabric or carbon backbone).
Relatively few classes of compounds are detected commonly in the environment (highlighted in yellow).
Most degradation intermediates are very short-lived or even just inferred.
Degradation mechanisms and pathways are complex & only partially understood with many unknowns remaining.
Other classes of PFAS (e.g. sulfonamides, PAPs) have similarly complex and challenging degradation mechanisms and pathways.
Carboxylic acid Telomer alcohol
Unsat. telomer acid Telomer acid
Sec alcohol
Unsat. acid
Telomer acid
Unsat. telomer acid
Carboxylic acid
Carboxylic acid
Carboxylic acid 2H acid
9
Co-contaminants at PFAS sites • Fire Training and Emergency Response sites
• BTEX • Chlorinated solvents • 1,4 dioxane • Surfactants and AFFF components
• Manufacturing – production and secondary • PFAS Residuals from product formulation/production • Non-PFAS Surfactants, solvents
• Metal Plating • Metals • Solvents
• Co-contaminants are important:
• Co-contaminants can impact analytical methods • The impact of co-contaminants on treatment systems targeting PFAS • May be regulated or targeted for remediation as well • May provide evidence regarding environmental conditions and performance
of treatment systems.
ANALYTICALMETHODS
11
Overview: PFASs Analytical Methods
• PFAAs Methods
Drinking Water: EPA Method 537 Version 1.1 • Six (6) PFAS for the UCMR3 + 8 additional PFAS • Finished (treated) drinking water samples… only!
Media other than drinking water: • EPA OLEM, OW, and ORD currently conducting a multi-laboratory validation
effort to establish EPA method(s) for non-DW media • Until standard methods are complete - Each commercial lab has their own
• Performance data is needed similar to that validating Method 537 • Data from different laboratories (different methods) may not be comparable • QA/QC comparable to 537 should be included regardless of the method along with
prescreening supplies and QA controls
• PFAS precursors – EPA ORD, EPA Region 5, and others are developing methods in non-DW matrices (surface waters, groundwaters, wastewater, biosolids, soils, sediments, etc).
• PFAS unknowns from transformations, degradation, new formulations, etc– EPA ORD and others are developing methods to identify unknown PFAS in environmental samples
EPAMethod537• DrinkingWaterOnly
• SolidphaseextracCon(SPE)followedbyLC/MS/MSanalysis
• 14TargetAnalytes:– 9PFCAs-PFHxA,PFHpA,PFOA,PFNA,PFDA,PFUnA,PFDoA,PFTriA,andPFTreA
– 3PFSAs-PFBS,PFHxS,andPFOS– 2precursors-N-EtFOSAA,andN-MeFOSAA
• 3SurrogateStandardsMPFHxA,MPFDA,MN-EtFOSAA
• 3Internalstandards13C-PFOA,13C-PFOS,d3-N-MeFOSAA
EPAMethod537protocol
Evaporate Internal Standard 1 ml 96% MeOH
LC/MS/MS
250 ml 250
ml
Surrogate 10 ml/Minute 4 ml MeOH Elute
Courtesy of William Lipps, Shimadzu
Method537QuanCtaCon/Surrogates
Time3.00 3.50 4.00 4.50 5.00 5.50 6.00 6.50 7.00 7.50 8.00 8.50 9.00 9.50 10.00 10.50
%
0
100
020817leva7 24: MRM of 2 Channels ES- 713 > 669 (PFTreA669)
9.88e4
10.67
MNEtFOSAA, S
MPFHxA, S
MNMeFOSAA, IS
MPFOS, ISMNEtFOSSA, S
MPFOA, IS
T
T T
S S
S
Courtesy of Larry Zintek, EPA
Targetcompound(T)usinginternalstandardquanCtaCon
• SuscepCbletomatrixinterferencethataffectstheinternalstandards(IS)• Generallylessofaproblemfordrinkingwater
• Maybeanissuefor“dirCer”matrices
Surrogatestandards(S)
• UsedtomonitortheanalyCcalmethod
• Notusedto“correct”concentraCon
• Comparetargetanalyterecoveryinmatrixspikestothesurrogates.
Method5371.1-Performancedata
Fourwatermatrices:Reagentwater(lowspike),Reagentwater(highspike),Chlorinatedgroundwater,HighTOC(5mg/L)groundwater.7replicatesofeachmatrix
70
80
90
100
110
120
130
meanrecovery(%)
PFOA PFOS 13C-PFHxA NEtFOSAA d5-NEtFOSAA
Mean recovery (error bars are %RSD)
WhynotuseEPAMethod537forMatricesotherthanDrinkingWater?
• Method537isadrinkingwatermethod!– Notdemonstratedforothermatrices– Co-contaminantsimpactmethods
• QuanCtaConismoredifficultindirCermatrices– OnlyoneSRMtransiCon=lessconfirmaCon– InternalStandardsignalsuppressionandenhancementcanbeanissue
• 537requiresSolidPhaseExtracCon– Challengingforwiderangeofanalytesofinterestinoneanalysis– Pre-filtersampleswithparCculates(Biaslowresults)– Timeconsuming
• Limitednumberofsurrogatestomimictheextendedanalytetargets
• ConcentraConbyevaporaCngtodryness– LosevolaClePFAS– Concentratesmatrixinterferences
Method Validation for ground, surface, and wastewaters • 24 PFASs (including all target analytes in EPA Method 537)
• Methods under consideration (all using LC/MS/MS) • Direct injection • Solid phase extraction (with and without labeled internal standard correction)
• Direct injection • Similar to draft EPA Reg 5 SOP • Targeting DL’s in 10’s ng/L • Phase 1: 5 internal (EPA) lab validation • Phase 2: 10 external lab validation
• Schedule: • Assess methods through Winter 2017-Summer 2018 • Publish draft method in Fall 2018
EPA PFAS Methods Validation
Method Validation for solids (soil, sediment, sludge) • Same 24 PFAS • Commence in Spring 2018 • Working toward early 2019 for draft methods • Target DL’s in the 0.1 - 2.5 ug/kg range
Sampling/Storage needs • Holding time studies • Sample vessel materials • Standard operating procedures for field sampling
EPA Points of Contact: OLEM Schatzi Fitz-James ([email protected]) Region 3 Cynthia Caporale ([email protected]) ORD Chris Impellitteri ([email protected]) Communications Michelle Latham ([email protected])
EPA PFAS Methods Validation
ASTMMethod7979-17• EnvironmentalWaters(notdrinkingwater)
• DirectInjecConanalysisbyLC/MS/MSissimilartoReg5SOPasthefirstmethodevaluatedbyEPAworkgroup
• 30TargetAnalytes:– 11PFCAs-PFBA,PFPeA,PFHxA,PFHpA,PFOA,PFNA,PFDA,PFUnA,PFDoA,PFTriA,PFTreA
– 7PFSAs-PFBS,PFPeS,PFHxS,PFHpS,PFOS,PFNA,PFDS– 12precursors–4:2FTS,6:2FTS,8:2FTS,6:2FTCA,7:3FTCA,8:2FTCA,10:2FTCA,6:2FTUCA,8:2FTUCA,n-MeFOSAA,n-EtFOSAA,FOSA
• Surrogatestandards(isotopic-labeledtargetanalytes):– 7PFCAs-MPFBA,MPFHxA,MPFOA,MPFNA,MPFDA,MPFUnA,MPFDoA
– 2PFSAs-MPFHxS,MPFOS
– UsedtomonitoranalyCcalmethod,notusedto“correct”thedata
• QuanCtaConwith2SRMsandionraCos
ASTM7979-17Protocol
10 µL Acetic Acid
LC/MS/MS
5 ml
Surrogate
Courtesy of William Lipps, Shimadzu
5 mL MeOH
ASTMPFASQUANTITATION
Time8.05 8.10 8.15 8.20 8.25 8.30 8.35 8.40 8.45 8.50 8.55 8.60 8.65 8.70 8.75 8.80 8.85
%
0
100
8.05 8.10 8.15 8.20 8.25 8.30 8.35 8.40 8.45 8.50 8.55 8.60 8.65 8.70 8.75 8.80 8.85
%
0
10082316lev4 14: MRM of 3 Channels ES-
498.9 > 98.9 (PFOS98.7)1.06e5
8.59
8.458.47
82316lev4 14: MRM of 3 Channels ES- 498.9 > 79.9 (PFOS79.7)
1.51e58.59
8.468.40 8.40
Time8.05 8.10 8.15 8.20 8.25 8.30 8.35 8.40 8.45 8.50 8.55 8.60 8.65 8.70 8.75 8.80 8.85
%
0
100
8.05 8.10 8.15 8.20 8.25 8.30 8.35 8.40 8.45 8.50 8.55 8.60 8.65 8.70 8.75 8.80 8.85
%
0
1008231608004_18 14: MRM of 3 Channels ES-
498.9 > 98.9 (PFOS98.7)1.36e5
8.60
8.40
8.39
8.23
8.458.46
8.47
8.62
8.64
8231608004_18 14: MRM of 3 Channels ES- 498.9 > 79.9 (PFOS79.7)
1.52e58.60
8.40
8.38
8.24
8.45
8.62
Ion Ratio-1.41 Ion Ratio-1.35
Quantitation Ion
Confirmation Ion
Calibration Sample
Courtesy of Larry Zintek, EPA
• BecauseofdirCermatrices–use2SRMtransiConsorMRM
– MeasureconfirmatorytransiConandionraCos– ExampleforPFOS,samesamples.IonRaCoDifferenceis4.3%andwithinTolerance
ASTM7979Performancedata
FourforCfiedmatrices:Reagentwater,Riverwater,WWTPeffluent,andWWTPinfluent*.6replicatesofeachmatrix.
*PFOSnotshownbecausethematrixhadbackgroundconcentraConcomparabletospikeconcentraCon
Mean recovery (error bars are %RSD)
70
80
90
100
110
120
130
mean recovery
(%)
PFOA MPFOA PFOS MPFOS 8:2 FTCA MPFNA
ASTMD7968
• Environmentalsolids:soil,sediment,sludge,etc
• SolventextracCon,analysisbyLC/MS/MS
• 30TargetAnalytes:– 11PFCAs-PFBA,PFPeA,PFHxA,PFHpA,PFOA,PFNA,PFDA,PFUnA,PFDoA,PFTriA,PFTreA
– 7PFSAs-PFBS,PFPeS,PFHxS,PFHpS,PFOS,PFNA,PFDS– 12precursors–4:2FTS,6:2FTS,8:2FTS,6:2FTCA,7:3FTCA,8:2FTCA,10:2FTCA,6:2FTUCA,8:2FTUCA,n-MeFOSAA,n-EtFOSAA,FOSA
• Surrogatestandards(isotopic-labeledtargetanalytes):– 7PFCAs-MPFBA,MPFHxA,MPFOA,MPFNA,MPFDA,MPFUnA,MPFDoA
– 2PFSAs-MPFHxS,MPFOS
– UsedtomonitoranalyCcalmethod,notusedto“correct”thedata
• QuanCtaConwith2SRMsandionraCos
Tumble 1 hr
ASTMD7968protocol
20 µL NH4OH
LC/MS/MS
Surrogate
Courtesy of William Lipps, Shimadzu
10 mL MeOH 2 g sample
10 µL Acetic Acid
ASTMD7968PerformanceData
FourASTMsoilmatrices:CL-1,CH-1,SP-1,andML-1.6replicatesofeachmatrix.*PFOSnotshownforSP-1andML-1becausethematriceshadbackgroundconcentraConcomparabletospikeconcentraCon.
50
60
70
80
90
100
110
120
130
mean recovery
(%)
PFOA MPFOA PFOS MPFOS 8:2 FTCA MPFNA
Mean recovery (error bars are %RSD)
ResearchMethods
• ORDlaboratoriesandotherresearchgroupshavedevelopedmethodstoanalyzerelevantmatricesforvariousPFAS
• Thesemethodsmayworkforyourstudy/site
• Todecide:– ReadandunderstandtheSOP– Reviewperformancedata
– ReviewandimplementQA/QCmeasures
DoDMethods
• CommercialLabsaccreditedbyDoDQSM5.1– AccreditaConcanbewithdrawn–checkifcurrent– NotclearwhatperformanceandQA/QCinformaConwasprovidedforaccreditaCon
• SOPs:– Varyfromcommerciallabtocommerciallab– OqencitedasconfidenCalbusinessinformaCon
• Manycommerciallabsuse“ModifiedMethod537”– ModificaConsarenotpermiredbyMethod537– NodatatoshowmodificaConswork
AnExampleCommercialMethod
Isotope addition
Bottle rinse
Elute
Internal Standard
Reconstitute in solvent
LC/MS/MS
Sample concentration
Extraction using SPE
CommercialMethods
• AnalyteconcentraConsare“corrected”forisotoperecovery– Ifrecovery<100%,concentraConsincrease– If>100%,concentraConsdecrease– Somelabs“correct”withverylowrecoveries
• MayormaynotuseconfirmaConionandionraCos–readtheSOP
• PerformanceDataisneededtoproperlyevaluateanymethodandtheQA/QCofthelaboratory.Thisdataisrarelyprovided.
Precursors
u PFAAsaremorecommonlymeasuredu PrecursorsmassmaybesubstanCalu AirexposureandoxidaCveremediaConforotherchemicalsmayconvert
precursorstoPFAAsoverCmeorduringtreatment
PFAS = Per- & Polyfluoroalkyl Substances includes PFOA or PFOS and precursors
PFAAs = Perfluorinated alkyl acids includes PFOA and PFOS
Etc.
PFAS Product (e.g. AFFF)
contains
Precursor A
Precursor B
Aerobicallyoxidized PFAAs
+ ??
PFAAs
TransformaContoformPFOA
(ModifiedfromWangetal.,2009)
Stable
Stable Stable
GC/MS/MS LC/MS/MS
AnalysisofPrecursors• NRMRLSOPsforEnvironmentalWaters(notDW)andsolids
• Methods– Water-SPE,analysisbyGC/MS/MS
– Solids–solventextracCon,analysisbyGCMS/MS
• Analytes:– FluorotelomerAlcohols(FTOHs)-4:2,6:2,8:2,7:2s,5:1,6:1,7:1,8:1,9:1,10:1,and11:1
– Fluorotelomermonomers-6:2FluorotelomerAcrylate(6:2FTAc),6:2FluorotelomerMethacrylate(6:2FTMAc),8:2FTAc,8:2FTMac,10:2FTAc,and10:2FTMac
– Perfluoro-1-octanesulfonamido-ethanol(FOSE)-2-N-ethylFOSE(N-EtFOSE),and2-N-MethylFOSE(N-MeFOSE)
• Surrogatestandards-8:2MFTOHandd7-MeFOSE
• QuanCtaConsimilartoASTMmethod–monitoring2SRMsandevaluaCngionraCos
TotalOxidizablePrecursors(TOP)assay• DevelopedbyHoutzetal• AvailablefromsomecontractlaboratoriesandunderevaluaConatORD• Nostandardmethodscurrentlyexist
• BulkPrecursorconcentraConcanbeesCmatedby: C2–C1=precursors
• DoesnotidenCfyindividualprecursorcompounds
1
2
Measure PFAA concentration (C1)
Persulfate Hydroxide Heat 6 hrs
Measure PFAA concentration (C2)
Non-TargetedMethodsExploreUnknowncompoundsusingHighresoluConmassspectrometry
apeakinachromatogramandtoulCmatelypredicttheidenCtyofthisunknown
↓ IniCally,themassspectrometerassignsamassforeachpeakobserved,forexample179.9846Daltons(Da)
↓ Soqwarethencalculatestheexactnumberandtypeofatomsneededtoachievethatmeasuredmass,exampleC3HF5O3(needthisnumberandtypeofatomstoweighthismuch)
↓ SoqwareandfragmentaConexperimentsallowdeterminaConofmostlikelystructure:
↓ Withmass,formula,andstructuredetermined,idenCtycanbeassignedbysearchingagainstdatabasesofknowncompounds
↓ SearchforstandardsfromcommercialsourcestoconfirmidenCficaConifpossible
O
FF
F
FF
OH
O
Molecular Formula: C3HF5O3
Monoisotopic Mass: 179.984585 Da[M-H]-: 178.977308 Da
SAMPLINGGUIDANCE
Sampling and Laboratory Considerations
• Solvent contamination is source dependent and can be consistent and/or sporadic • Laboratory supplies
• Polypropylene vials and centrifuge tubes (from mold release or cross contamination from other production processes)
• LC vial caps and septa (e.g. PTFE/silicone) • LC and SPE pump equipment, pump head seals (graphitized Teflon) • PTFE tubing • Low binding pipette tips
• Use of PFAS-containing equipment (gloves, coats, collection gear, etc) also an issue
• Many common laboratory/field materials and sampling
equipment contain PFAS (pipette tips, filters, vials, etc)
• Other chemicals which may be present
• e.g., AFFF sites may have hydrocarbons, chlorinated solvents, glycols, and other AFFF components as well as residuals from previous remediation efforts
• Research needed to evaluate professional judgement:
• Volatile PFAS may be lost depending on the sampling methods.
• PFAS stratification? • PFAS may sorb to sampling equipment
possibly distorting measured concentration
37
Sampling and Analytical issues
Lessons learned from ORD Tech Support for on-going preliminary site investigations:
• Sampling approach and equipment not evaluated for PFAS
• Low sample density – heterogeneity unknown
• Co-contaminants not sampled at the same time
• Many conducted by federal partners with limited input from EPA
• Site characterization and source identification affected by: • Many PFAS-products used with varying formulations, chemistries, etc • Lengthy time in the environment could result in transformations • Co-contaminants present • Remediation technologies used to clean up other chemicals may impact PFASs
concentrations and distributions
38
PFAS Sampling
• Information is evolving! – check for updates often
• Sample integrity
– The collected sample should represent the matrix sampled
– Don’t add PFAS to your sample – Don’t remove PFAS from your sample
• Non-ideal situations
– Historical wells may contain fluorocarbons – Safety trade-offs with issues of cross contamination
AccuratePFASSampling:CrossContaminaNon
• Don’t add analytes to your sample
• PFAS found in many common field supplies and equipment
• Fluoropolymers – equipment, seals, sample caps and bottles • Water proof paper and PPE • Personal care products • Surface treatment on aluminum foil, food wrappers
• Sunscreens
Avoid using these items if not specifically screened for PFAS!
Sampling Procedure Precautions: PPE
Personal Protective Equipment (PPE)
• Preferred – well washed clothing
• Uncoated Tyvek ok, coated Tyvek may contain PFAS
• Stain repellent clothing contains PFAS
• Water Repellent clothing
– PFAS based treatments have many trade names such as Gore-tex, weatheredge, DWR, Omni-tech
– Claims of “PFOS free” may contain C6 PFAS – Read labels and product descriptions carefully – Rubber, polyurethane, and PVC - ok
Sampling Procedure Precautions: Equipment
Sampling Equipment and supplies
• No teflon or PTFE permitted
• Fluoropolymers – generally no
• Aluminum foil may have PFAS surface treatment
• No Decon 90, sharpies, post-it notes, waterproof field papers or books
• Avoid chemical ice packs
Acceptable materials
• HDPE, polypropylene, and silicone materials
• Alconox or Liquinox
• Ball point pens
• Water ice – double bag in polyethylene bags
Sampling Procedure Precautions
Other
• Food packaging may contain PFAS treatments – don’t eat on site, and wash hands before returning to site
• Frequent nitrile glove changes
• Collect field blanks
• Field spiked blanks used by some
• Avoid re-using equipment - previous use may have involved PFAS materials
Best practice
• Pretest materials and products for PFAS contamination
• Keep separate from “normal” sampling supplies
PFAS Sampling Guidance
• Cross-EPA workgroup – Generic SOP for groundwater sampling external review soon – SOPs for surface water, soil, etc to follow
• Interim Guideline on the Assessment and Management of Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS)Contaminated Sites Guidelines – Gov’t of State of Western Australia
• US States – Department of Environmental Protection, Massachusetts – New Hampshire Department of Environmental Services
Conclusions
• Significant investment in PFAS related research is starting to show results. Standardized methods and sampling approaches are being developed currently.
• Source control (in the form of pretreatment or elimination of source) is the most cost effective means of managing the risk of these chemicals.
• More research is needed to develop better cost models for treating PFAS in drinking water and other environmental media.
• Treatment and remediation technologies are needed for a wide variety of media under a wide variety of environmental conditions
• Careful science-based decisions are needed to evaluate replacement and alternatives to PFAS-based chemistries.
Acknowledgements
• Regions
§ Jane Dolan (Reg 1) § Dave Einan (Reg 10) § Kim Prestbo (Reg 10) § Kira Lynch (Reg 10) § Diana Cutt (Reg 2) § Chuck Maurice (Reg 5) § Jan Szaro (Reg 1) § Carol Braverman (Reg 5) § Cindy Caporale (Reg 3) § Barry Pepich (Reg 10) § Karin Lethe-Fedderson (Reg 10)
46
• OLEM
§ Schatzi Fitz-James § Linda Gaines § Linda Fiedler § Jed Costanza
• ORD
§ Chris Impellitteri § Gerard Henderson § Jennifer Goetz § Jody Shoemaker § Jim Voit
References Chemistry
• Buck et al. 2011. Integrated Environmental Assessment and Management. 4:513-541
• Backe et al. 2013. Environmental Science and Technology. 47: 5226�5234
• Wang et al. 2017. Environmental Science and Technology. 51:2508-18
• Liu and Avendano. 2013. Environment International. 61:98-114
• ITRC Fact sheets (http://www.itrcweb.org/Team/Public?teamID=78)
• http://www.cluin.org/pfas
• https://www.epa.gov/pfas/basic-information-about-and-polyfluoroalkyl-substances-pfass#tab-1
Analytical Methods
• Method 537 1.1
• ASTM D7979-17 and D7968-17
• NRMRL SOPs – contact Marc Mills
• TOP assay - Houtz and Sedlak. 2012. Environmental Science & Tech. 46(17): 9342-9349.
• PIGE - Srivastava, A., et al. Journal of Radioanalytical and Nuclear Chemistry 302.3 (2014): 1461-1464.
• https://www.epa.gov/pfas/and-polyfluoroalkyl-substances-pfass-what-epa-doing 47
References Sampling Guidance
• Cross-EPA workgroup
– Generic SOP for groundwater sampling external review soon
– SOPs for surface water, soil, etc to follow
• Interim Guideline on the Assessment and Management of Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS)Contaminated Sites Guidelines – Gov’t of State of Western Australia (https://www.der.wa.gov.au/images/documents/your-environment/contaminated-sites/guidelines/Guideline-on-Assessment-and-Management-of-PFAS-.pdf)
• ITRC and DOD in development
• US States
– Department of Environmental Protection, Massachusetts
– New Hampshire Department of Environmental Sciences
48
Disclaimer
TheviewsexpressedinthispresentaConarethoseoftheindividualauthorsanddonotnecessarilyreflecttheviewsandpoliciesoftheUSEPA.MenConoftradenamesorcommercialproductsdoesnotconsCtuteendorsementorrecommendaConforuse
OxidaCvetransformaContoformPFOA
(ModifiedfromWangetal.,2009)Stable
Stable
Stable
OxidaCveTransformaContoformPFOS
Perfluoroalkyl sulfonamide (FOSA)
SO2NH2
N-alkyl perfluoroalkyl sulfonamidoacetic acid
(RFOSAA)
SO2N(R)CH2COO-
Perfluoroalkyl sulfonamidoacetic acid (FOSAA)
SO2NHCH2COO-
Perfluorooctane sulfonic acid (PFOS)
SO3-
N-alkyl perfluoroalkyl sulfonamido ester/urethane monomer
SO2N(R)CH2CH2OCOM M = acrylate, methacrylate, urethane
N-alkyl perfluoroalkyl sulfonamidoethanol (RFOSE)
SO2N(R)CH2CH2OH R = methyl, ethyl
Ester / Urethane Polymer
Stable