Navigating the Challenges for the
Analysis of PFAS in Environmental
Matrices to Meet TRRP Requirements
Charles Neslund, Technical Director
TCEQ Environmental Trade Fair, May 16-17, 2017
Providing comprehensive scientific resources to
environmental clients worldwide.
www.LancasterLabsEnv.com
Polyfluorinated Compounds
• 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
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Polyfluorinated Compounds
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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Polyfluorinated Compounds
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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Polyfluorinated Compounds
• 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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Polyfluorinated Compounds
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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PFAS
Perfluorooctanoic acid (also known as PFOA)
MW = 414 amu
BP = 189-192 °C
Density = 1.8 grams/ml
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PFAS
Perfluorooctane sulfonic acid (also known as
PFOS)
MW = 500 amu
BP = 133 °C at 6 torr
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PFAS
• 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
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Polyfluorinated Compounds
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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Polyfluorinated Compounds
Perfluorobutanoic acid
Perfluoropentanoic acid
Perfluorohexanoic acid
Perfluorheptanoic acid
Perfluorooctanoic acid
Perfluorononanoic acid
Perfluorodecanoic acid
Perfluoroundecanoic acid
Perfluorododecanoic acid
Perfluorotridecanoic acid
Perfluorotetradecanoic acid
Perfluorohexadecanoic acid
Perfluorobutanesulfonate
Perfluorohexansulfonate
Perfluoroheptanesulfonate
Perfluorooctanesulfonate
Perfluorodecanesulfonate
Perfluorooctanesulfonomide
Methylperfluoro-1-octanesulfonamide
Ethylperfluoro-1-octanesulfonamide
4:2 Fluorotelomer sulfonate
6:2 Fluorotelomer sulfonate
8:2 Fluorotelomer sulfonate
10:2 Fluorotelomer sulfonate
N-methylperfluoro-1-octanesulfonamidoacetic acid
N-ethylperfluoro-1-octanesulfonamidoacetic acid
2-(N-methylperfluoro-1-octanesulfamido)-ethanol
2-(N-ethylperfluoro-1-octanesulfamido)-ethanol
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Polyfluorinated Compounds
• 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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Advisory Limits
• 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
PFOA = 0.3 ug/l
PFBS = 7 ug/l
PFBA = 7 ug/l
• New Jersey preliminary health based guidance**
PFOS = 0.2 ug/l
PFNA = 0.01 ug/l
PFOA = 0.04 ug/l (** 0.014 ug/l)
• Vermont Groundwater Enforcement Standard
PFOS = 0.02 ug/l
PFOA = 0.02 ug/l
• EPA Region 4 levels in soils
PFOS = 6 mg/kg
PFOA = 16 mg/kg
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Advisory Limits - Update
* 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
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Tier 1 Groundwater PCLs
Compound
CAS #
Conc ng/l
Perfluorooctanoic 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
72629-94-8
290
754-91-6
290
Perfluorotridecanoic acid
Perfluorooctane sulfonamide
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Analytical Methodology
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
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Analytical Methodology
• 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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Analytical Methodology
• 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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Analytical Methodology
• 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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UCMR3
Unregulated Contaminant Monitoring Rule
Perfluorinated Compounds (PFCs): EPA Method 537
included as UCMR3 List 1 Contaminants;
Compound
MRL ug/l
Perfluorooctanesulfonic acid
Perfluoroctanoic acid
Perfluorononanoic acid
Perfluorohexanesulfonic acid
Perfluoroheptanoic acid
0.04
0.02
0.02
0.03
0.01
Perfluorobutanesulfonic acid
0.09
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UCMR3
• 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
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Analytical Methodology
• 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…
Water
Reporting
Limits LOQ
(ng/L)
Soil
Reporting
Limits LOQ
(ng/g)
Analyte
Acronym
Perfluorohexanoic acid
PFHxA
2
0.4
Perfluoroheptanoic acid
PFHpA
2
0.6
Perfluorooctanoic acid
PFOA
2
0.6
Perfluorononanoic acid
PFNA
2
0.4
Perfluorodecanoic acid
PFDA
2
0.4
Perfluoroundecanoic acid
PFUnDA
3
0.6
Perfluorododecanoic acid
PFDoA
2
0.6
Perfluorotridecanoic acid
PFTrDA
2
0.6
Perfluorotetradecanoic acid
PFTeDA
2
0.6
Perfluorobutanesulfonate
PFBS
2
0.6
Perfluorohexanesulfonate
PFHxS
2
0.6
Perfluoro-octanesulfonate
PFOS
6
0.9
8:2 fluorotelomersulfonate
8:2 FtS
10
0.9
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Analytical Methodology
• 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
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Instrumental Analysis
Analytical Methodology
• 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
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Instrumental Analysis
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.
Analytical Methodology
• 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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Analytical Methodology
Total Ion Chromatogram of Technical Grade Standard
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Analytical Methodology
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Future
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.
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Future – TOP Analysis
TOP – Total Oxidizable Precursors
Based 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 precursors
b. Increase in concentrations of perfluorinated acids
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Summary
• 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
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Questions
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