the analysis of per and polyfluorinated alkyl substances
TRANSCRIPT
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2018 TCEQ Trade Fair – PFAS Presentation
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The Analysis of Per and Polyfluorinated Alkyl Substances (PFAS) Challenges and Best Practices
Karla Buechler – Corporate Technical Director
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PFAS - OutlineIntroduction to PFASsWhat are PFASs?Nomenclature/ChemistrySources, Timeline, FormationExposure, Toxicity and RiskRegulatory ReviewAnalytical Best PracticesAnalytical Methods reviewWhy so much variability?How do we reduce variability?New In Line SPE CapabilityFuture Concerns – TOP AssayAlternative chemicals – GenXCapabilities and Questions?
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Briefly - What are PFASs?Class of synthetic compounds containing thousands of chemicals formed from carbon chains with fluorine attached to these chains.
The C-F bond is the shortest and the strongest bond in nature.
PFOS and PFOA are fully fluorinated and the most common perfluorinated chemicals (PFCs).
Persistent and resistant to degradation Found in soil, air and groundwater..
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NomenclaturePFAS – Broad term – completely
and incompletely fluorinated PFC – Subset of PFAS
completely fluorinated compounds. PFOS and PFOA are PFCs (no hydrogen atoms)
PFAAs – Perfluoroalkyl acids – 2 classes PFCAs and PFSAs
AFFF – Aqueous Film Forming Foam –mixture of PFCAs, PFSAs, and PFAA precursors
Fluorochemicals and telomers
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Chemical StructureWhy is it Important?
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Perfluoroalkyl Carboxylate
Fluorotelomer Sulfonates
Perfluoroalkyl SulfonatePerfluoroalkyl Sulfonamido Amines
Perfluoroalkyl Sulfonamido acetic acid amine
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Primary Sources – Point or Direct
Released in large quantities from primary manufacturing facilities
Secondary Manufacturing –incorporation of PFC raw materials into industrial and consumer products
The use of AFFFs to fight fires is a direct pathway to the environment –(Connection to DoD)
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Secondary Sources -Indirect Commercial and
consumer products have a finite lifetime. Dispose to landfillsWWTP Air emissions
Trace chemistry –transformation mostly degradation by-products (TOP Assay)
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Environmental Exposure Pathways Oliaei, Environ Pollut Res. (2013): 1977-1992
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Exposure, Toxicity and Risk
Major source of non-occupational exposure to humans is from food and air (predominately fish consumption)
Human and wildlife exposure can continue even though the chemicals are no longer in use, due to persistence.
PFOS and PFOA have half-lives in humans ranging from 2 to 9 years, depending on the study.
PFOA associated with liver, pancreatic, testicular, and mammary gland tumors in laboratory animals. PFOS causes liver and thyroid cancer in rats
PFOA and PFOS are associated with cancers in humans. Pathways are being studied.
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Regulatory Challenges and New Developments
Lack of regulatory guidance for most matrices and most PFAS compounds
Wide variety of detection limits and analyte lists
Lack of published methodsWhat is Method 537M?What are the ASTM
Methods?What is the ISO Method
25101?
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PFAS – Regulatory TimelineWhen Who What Happened
1980s EU Groundwater directive to prevent discharge of PFOS
2002 US EPA Initiated voluntary phase out of PFOS
2002 3M Discontinued making PFOS (7 other makers complied)
2006 US EPAAnnounced 2010 (95%)/15(100%) PFOA Stewardship Program
2008 Canada Regulated and prohibited PFOS imports to Canada
2009 UN Stockholm Convention - adds PFOS to Annex B
2010 US EPA2010 PFOA Stewardship program - must reduce PFOA use by 95%
2015 US EPA Must 100% eliminate the use of PFOA by December 31,2015.
May 2016 US EPA PFOS and PFOA life time health limits reduced to 70 ppt each or the total if both are present.
Sept 2016 NJ DWQI proposed PFOA drinking water MCL of 14 ppt
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What started happening in 2016?
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What’s Up in New Jersey? (12/2017)
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State PFOA ppt PFOS ppt Comments SourceAlabama 70 70 EPA
Alaska 400 400 ADECCalifornia Prop 65 Prop 65 Proposed OEHHA
Connecticut 70 70 PFNA, PFHxA, PFPeA, PFHpA DPH
Delaware 70 70 DNRGeorgia 70 70 Proposed DPHIllinois 400 200
Iowa 70 70 DNR
Kentucky 400 200 NKWDMaine 70 70 ME DEP
Maryland 70 70Michigan 5 proposed 5 proposed MI DEQ
Minnesota 35 27 MDHNew Hampshire 70 70 DES
New Jersey* 14 13 NJDEP
New York 70 70North Carolina 2000 NA DENR
Ohio 400 200 EPA
Oregon 24000 300000 PFHpA, PFNA, PFOSA
Pennsylvania 70 (May lower to 6) 70 PA DEP
Rhode Island 70 70Texas 290 560 PCLs for 16 PFCs CEQ
Vermont 20 20 VT DOH
Washington NA TBD Listed PFOS as PBT
West Virginia 400 200
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Why are PFAS an Analytical Challenge?
Globally distributed Present at low
concentrations and high Contamination and analyte
loss at all stages of collection and analysis
Lack of authentic standards Unusual physical and
chemical properties Lack of consensus “best”
method for non-DW
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PFAS Analytical Methods-Best Practices Manufacturer’s methods were
adopted by the environmental industry – SW-846 Method 8321
EPA expanded manufacturer’s method for drinking water-Method 537
Labs had to modify Method 537 in order to meet client needs for additional matrices
Sept 2016 EPA- Method 537 Technical Advisory
January 2017 DoD QSM 5.1 addresses PFAS
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Why so much method variability? Inconsistent quantitation of branched and linear isomers Absence of multi-lab validated methods Limited certification programs Differences in extraction efficiencies – analyte sorbent dependent External, internal and isotope dilution quantitation schemes Lack of proven commercially available PT samples Use of different isotopically labeled extraction surrogates Lack of commercially available standard materials and true second
sources Target analyte losses during filtration Absence of demonstrated cleanup techniques for complex matrices Wide variety of container types and holding times
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Show Branched and Linear Error in PFOS and PFOA
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Standard
Sample0.99 vs 1.20 ng/ml
B and L L only
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Study Results - NMI PT
Sample Analyte Sac Lab ExpectedWater A PFOA 7.91 7.90
PFOS 3.23 3.00Water B PFOA 9.01 10.8
PFOS 6.81 6.50Soil A PFOA 7.00 5.83
PFOS 290 262Soil B PFOA 14.2 12.0
PFOS 23.5 22.0Fish A PFOA ND ND
PFOS 19.9 20.6Fish B PFOA 51.4 50.5
PFOS 49.2 53.7
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24 labs submitted results – 9 Passed
TestAmerica passed water, soil and fish tissue samples
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Sample Collection and Holding Time Studies
Samples should be collected in HDPE bottles fitted with unlined (no Teflon) polyethylene screw caps.
In addition, the sampler should avoid contact with fluoropolymers, aluminum foil, and food wrappers.
Samples should not be field filtered.
Samples must be shipped chilled Limited HT study data
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Managing Artifacts The field crew – personnel hygiene,
clothing, food products, sunscreens and insect repellants
Sampling equipment – avoid fluoropolymer bailers, pump bladders, tubing, valves etc.
Sample collection – wash hands, wear nitrile gloves, do not filter samples, add field QC samples routinely
Avoid detergents Avoid food or drink on-site Limit visitors during sample
collection
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Sources of Artifacts
USEPA Study, March 2009 EPA/600/R-09/033
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Managing Loss/Adsorption
Many PFAS are surface active, which cause them to stratify, adsorb to surfaces
Extraction type – whole bottle or subsample play a more significant role then material type
PFAS can adsorb to the filtration equipment. PFAS in the dissolved phase can also adsorb to the filter material
Unless the samples are analyzed immediately adsorption to glass vials may occur
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How can we mitigate analytical variability? Apply tandem mass
spectrometry technology Implement an isotope
dilution quantitation scheme
Compensate for losses with matrix recovery correction
Share our knowledge Invest resources in multi-
lab validation
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What is Isotope Dilution?
Most accurate and precise calibration method available
Partial loss of analyte during preparation is compensated for since chemical interferences are not an issue
Allows for matrix recovery correction – what affects the native analyte will equally affect the isotope
Correction for signal drift Improved qualitative
identification – RT shifts
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What is it? Dilute a water sample with
methanol and inject a large volume onto a modified UPLC
What are the advantages? Simplicity – reduced sample
manipulation Reduced sample volume (5 mls) Speed, reduced TAT Increased capacity Reduced risk of laboratory
background artifacts
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Method 537M – In Line SPE
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What are Precursors and Why Do We Care? Thousands of precursors
used in industrial and consumer products
Some biotransform to make PFAAs
Some are fluorotelomers Most are ionic, either
positive, negative or both Fate and transport –
complex process
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What is the TOP Assay?
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A new PFAS sample preparation technique
Quantified Transformation
Unknown Potential
Conceptually simple chemistry
Used with 537M not 537
Pre and Post results
Indicates unidentified PFAS
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How Does it Work in the Environment?
Low levels of discrete compounds are detected
High levels of discrete compounds are detected, which can include PFOA and PFOS
PFAA PrecursorsBiotransformation
PFOA
PFOSOutflow
PFAA
Inflow
Give me an example:
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TOP – How Does it Work in the Laboratory?
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PFAA Precursors OH•
OH•OH•
PFOA + other PFCAs85°C
85°C
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PFCA Pattern – Me-FOSA Precursor
0
10
20
30
40
50
60
70
80
PFBA
PFPeA
PFHxA
PFHpA
PFOA
PFNA
ppt
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PFOA
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PFCA Pattern – 8:2 FTS
0
10
20
30
40
50
60
70
80
90
100
PFBA
PFPeA
PFHxA
PFHpA
PFOA
PFNA
PFHpA
ppt
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What Do the Results Mean?
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TOP Assay measures total PFCAPrecursor Pre - TOP Post - TOP % Oxidation
FOSA 32.68 ND 100%MeFOSAA 19.38 ND 100%EtFOSAA 18.83 ND 100%6:2 FTS 31.69 ND 100%8:2 FTS 26.37 ND 100%PFCA Pre – TOP Post - TOP TotalPFBA 24.94 27.16 109%PFPeA 23.38 28.55 122%PFHxA 26.49 34.87 132%PFHpA 23.10 25.14 109%PFOA 23.72 58.71 248%
Total 122 Total 174
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What Conclusions Can We Draw?
PFAA precursors are present in environmental samples and many AFFF products Implies treatment strategies must
remove precursors and end points Presence impacts our treatment
strategies and our risk assessments Potentially increases future risk as
precursors are biotransformed Presence impacts our decisions for
AFFF formulations AFFF manufacturers should reduce
the content of PFOA etc.
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Fluorinated Replacement Chemicals
Since 2000, on-going industrial transition to replace LC PFCAs, PFSAs and precursors
Many alternative chemicals are in use – below regulatory radar
Unclear whether they are safe for humans or the environment
DuPont developed patented GenX technology - enables them to make fluoropolymers without PFOA
GenX is not a chemical it is a process
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Replacement ChemicalsCAS # Name Synonym Source Use Manufacturer
73606‐19‐6 F‐53B (Major component)
6:2CL‐PFESA or 9CL‐PF3ONS TBD PFOS replacement
chemical Chenguang, China
83329‐89‐9 F‐53B (Minor component)
8:2CL‐PFESA or 11CL‐PF3OUdS TBD PFOS replacement
chemical Chenguang, China
958445‐44‐8 ADONA or DONA NH4
ADONA or DONA NH4 TBD PFOS replacement
chemical 3M and Dyneon
13252‐13‐6 PFPrOPrA HFPO‐DA GenX PFOA replacement chemical DuPont/Chemours
62037‐80‐3 PFPrOPrA NH4 HFPO‐DA NH4 GenX PFOA replacement chemical DuPont/Chemours
3330‐15‐2 PFPrPrA ether HFPO‐DA ether GenX PFOA replacement chemical DuPont/Chemours
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TestAmerica Capabilities TestAmerica Sacramento is EPA
approved for Method 537 in drinking water and ISO 25101 in NYS
Sacramento is QSM 5.1 Table B-15 approved for Method 537M
Sacramento, Denver and Burlington Labs are NELAP approved for Method 537M.
7 LCMSMS instruments capable of PFAS testing
Sacramento has successfully implemented the TOP Assay
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Future Concerns
We need a consensus “best” method.
Analyte lists are growing for discrete methods, may lead to forensics.
LC PFASs are being replaced by SC PFASs and little is know about the toxicity
On-going data variability must be improved
We need an effective field screening technique.
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The Analysis of Polyfluorinated Alkyl Substances (PFAS) Including PFOS and PFOA
Questions