Per- and Polyfluoroalkyl Substances (PFAS)

The universe of PFAS is large and contains chemicals whose different chemical properties mean that analytical and characterization techniques developed for some of these chemicals may not apply to all chemicals in the PFAS universe. The physical and chemical properties of PFAS can vary. Depending on the analytes of interest, one may need to consider whether chemicals are volatile.

Careful attention to the contamination potential for commonly used products and materials to affect the PFAS in a sample and avoidance of suspect materials may help to protect sample integrity. EPA Method 537 (Shoemaker et al. 2009), for example, points out that "contamination during sampling can occur from a number of common sources, such as food packaging and certain foods and beverages. Proper hand washing and wearing nitrile gloves will aid in minimizing this type of accidental contamination of the samples." Other considerations include selecting appropriate containers and equipment to prevent either PFAS loss through adsorption, or sample contamination through contact with PFAS-containing materials. Investigation of detection and collection equipment and sample handling materials may reveal components with the potential to affect sample integrity, such as Teflon tubing. More detail on these issues is found in the sections below.

Site Characterization

The characterization of sites to determine the presence and extent of PFAS compounds may involve water, soil, and sediment samples. Surface water and groundwater samples are important to understand the extent and degree of PFAS contamination. Surface soil samples may be important because some PFAS products such as aqueous film-forming foams (AFFF) are applied to soils in open areas or run off onto surrounding soil during use. In addition atmospheric deposition of PFAS near manufacturing and processing facilities can serve as the source of surface water and groundwater contamination (Rumsby et al. 2009; Dickenson and Higgins 2016). Subsurface soil samples could be important for locating regions of high PFAS concentration that may serve as long-term sources for groundwater contamination. Likewise, sediment and sediment pore water samples may be considered where groundwater discharge to surface water is possible.

Because of the low detection limits usually called for in a PFAS site investigation (ng/L or ng/kg) and the presence of PFAS in many products used in environmental work, the potential exists for the presence of certain commonly used materials on site or in equipment employed during the investigation to introduce sample contamination. Preserving sample integrity thus may require a careful evaluation of ordinary supplies and practices, followed by determination of materials and activities to avoid or prohibit on site. DON (2015), Chiang et al. (2016), and GWA (2017) detail potential issues associated with commonly used products and equipment and offer numerous recommendations for exceptions to general practice, as indicated by the examples listed below of accidental sources of sample contamination.

Clothing, food, and personal care products:

• New clothing, water/stain resistant articles (e.g., raincoats, Tyvek®), treated boots (waterproofed), clothing laundered with fabric softener.
• Fast food wrappers and containers, pre-wrapped foods and snacks (potato chips, candy, energy bars).
• Cosmetics, moisturizers, hand cream, lotions, sun screen, insect repellent.

Groundwater drilling and well development practices, supplies, and equipment:

• Well casing/screen construction material.
• Detergent used for decontamination.
• Personal protective equipment (boots, coveralls).
• Equipment that will be in contact with groundwater (surge blocks/bailers, downhole pumps, tubing, electronic water level gauges, etc.).
• Aluminum foil, waterproof paper notebooks and labels, self-sticking notes.

Conventional soil drilling and aquatic sampling (surface water and sediment) supplies:

• Detergent used for decontamination.
• Personal protective equipment (boots, coveralls).
• Core sampler lining.
• Sampling device or container to collect surface water samples.

Conventional sample handling and processing supplies:

• Sample container and lid construction material.
• Reusable chemical or gel ice packs.
• Permanent markers and marker pens for container labeling.
• Glove construction material.

In addition, PFAS may sorb to materials used in sampling (Obal et al. 2012). The effect on sample concentrations may be mitigated by: careful selection and prescreening of sampling materials; documentation and use of appropriate sampling procedures; and collection of appropriate control samples during field activities.

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General Sampling Guidance

Evaluating PFAS Cross Contamination Issues
Bartlett, S.A. and K.L. David.
Remediation Journal 28(2):53-57(2018) [Open Access]

The suggested conservative approach to PFAS sampling to avoid cross-contamination issues includes an evaluation of three insect repellent products to determine their suitability for use during PFAS investigation.

Field Equipment Cleaning and Decontamination at the FEC
U.S. EPA Region 4, Science and Ecosystems Support Division, Athens, GA.
SESDPROC-206-R3, 23 pp, 2015

Section 4 (pages 11-12) describes equipment used for sample collection for PFC analyses and addresses appropriate containers for decontamination solutions and equipment decontamination procedure.

Interim Guideline on the Assessment and Management of Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS): Contaminated Sites Guidelines
Government of Western Australia, Dept. of Environment Regulation, Perth. 29 pp, 2017

Appendix 1, "PFAS-specific Sample Collection Methods, Equipment, and Equipment Decontamination Methods," provides warnings and recommendations for PFAS characterization activities.

Interim Perfluorinated Compounds (PFCs) Guidance/Frequently Asked Questions
Naval Facilities Engineering Command, Ser 14014/EV3-KB, 19 pp, 2015

Basic information is given on site characterization methodology, including NAVFAC recommendations on sampling.

Sensors For Detecting Per- and Polyfluoroalkyl Substances (PFAS): A Critical Review Of Development Challenges, Current Sensors, and Commercialization Obstacles
Menger, R.F., E. Funk, C.S. Henry, and T. Borch.
Chemical Engineering Journal 417:129133(2021) [Abstract]

This review discusses sensors developed to detect PFAS by their molecular mechanism and the goals that should be considered during sensor development. Future research needs and commercialization challenges are also highlighted.

Site Characterization Considerations and Media-Specific Occurrence for Per- and Polyfluoroalkyl Substances (PFAS)
Interstate Technology and Regulatory Council (ITRC), 4 pp, 2022

The unique chemical characteristics, uses, and transport mechanisms of PFAS to consider when characterizing a contaminated site are discussed in this fact sheet.

Where is the PFAS? Innovations in PFAS Detection and Characterization
John Horst, Craig Divine, Joe Quinnan, Johnsie Lang, Erika Carter, Theresa Guillette, Vivek Pulikkal ǀ Groundwater Monitoring & Remediation 42(1):13-23(2022) [Abstract]

This article focuses on innovations and developing technologies tailored to the needs and challenges associated with the characterization of PFAS sites. The discussion reviews five innovative technologies, including passive and no-purge samplers for efficient routine monitoring, passive flux meters to characterize PFAS mass discharge, mobile laboratories for quantitative screening and decision making, real-time sensors for rapid characterization and continuous monitoring, and novel analytical techniques for reliable detection in complex sample matrices.

Air Sampling

Screening for PFOS and PFOA in European Air Using Passive Samplers
Chaemfa, C., J. Barber, S. Huber, K. Breivikc, and K. Jones.
Journal of Environmental Monitoring 12(5):1100-1109(2010) [Abstract]

Results are reported of using polyurethane foam-based passive air samplers (PUF-PASs) to sample ionic PFASs.

Aqueous Sampling

Analysis of Per- and Polyfluoroalkyl Substances in Houston Ship Channel and Galveston Bay Following a Large-Scale Industrial Fire Using Ion-Mobility-Spectrometry-Mass Spectrometry
Valdiviezo A, Aly NA, Luo YS, Cordova A, Casillas G, Foster M, Baker ES and Rusyn I. Journal of Environmental Sciences 115:350-362(2022) [Abstract]

Large quantities of PFAS-containing firefighting foams were deployed following the chemical fire at the Intercontinental Terminals Company in Deer Park, TX, in 2019. The release of PFAS into the Houston Ship Channel/Galveston Bay (HSC/GB) prompted concerns over the extent and level of PFAS contamination. A targeted liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based study of temporal and spatial patterns of PFAS associated with this incident revealed the presence of seven species whose levels gradually decreased over six months. Targeted LC-MS/MS analysis focused on ~30 PFAS molecules and may have missed other PFAS compounds present in firefighting foams. A non-targeted LC-ion mobility spectrometry-mass spectrometry (LC-IMS-MS)-based analytical approach was applied to 31 samples from nine HSC/GB sites collected over 5 months to conduct a more comprehensive characterization. Data showed that an additional 19 PFAS were detected in HSC/GB surface water; most decreased gradually after the incident. PFAS features detected by LC-MS/MS correlated well in abundance with LC-IMS-MS data, though LC-IMS-MS identified several additional PFAS, many known to be components of firefighting foams. Findings illustrate that non-targeted LC-IMS-MS can improve the understanding of PFAS presence in complex environmental samples.

Assessment of PFAS in Collocated Soil and Porewater Samples at an AFFF-Impacted Source Zone: Field-Scale Validation of Suction Lysimeters
Anderson, R.H., J.B. Field, H. Dieffenbach-Carle, O. Elsharnouby, and R.K. Krebs.
Chemosphere 308(Part 1):136247(2022) [Abstract]

PFAS occurrence was evaluated in lysimeter-collected porewater samples for two depth intervals at a decades-old aqueous film-forming foam (AFFF)-impacted field site quarterly for a year. Site-wide Log₁₀ (∑PFAS) concentrations did not significantly differ among sampling events despite highly variable sample yields due to a heterogeneous and dynamic soil moisture regime. However, Log₁₀ (∑PFAS) concentrations were significantly higher in the shallow interval concordant with higher mean soil concentrations and higher total organic carbon (TOC) reflecting net retention, which is supported by soil-to-groundwater annual mass discharge estimates less than 0.2% of the total source mass for any given PFAS. PFAS-specific Log₁₀ (soil-to-porewater ratios) significantly increased with soil concentration in both depth intervals contrary to concentration dependence resulting from the saturation of sorption sites potentially implicating self-assembly as an additional operative retention mechanism. Overall, these data validate the use of suction lysimeters for short-term site characterization deployments and emphasize the importance of in situ porewater samples for interrogating PFAS transport within source zones.

Determination of Perfluoroalkyl Compounds in Water, Sediment, and Biota
Ahrens, L., K. Vorkamp, P. Lepom, et al.
International Council for the Exploration of the Sea, ICES Techniques in Marine Environmental Sciences No. 48, 16 pp, 2010

An overview of environmentally relevant PFCs is followed by information on techniques for their analysis in samples of water, sediment, and biota, including sampling, pretreatment, extraction, cleanup, instrumental analysis, quantification and quality assurance, and quality control.

Development and Applications of Novel DGT Passive Samplers For Measuring 12 Per- And Polyfluoroalkyl Substances in Natural Waters and Wastewaters
Fang, Z., Y. Li, Y. Li, D. Yang, H. Zhang, K.C. Jones, C. Gu, and J. Luo. Environmental Science & Technology 55(14):954819556(2021) [Abstract]

A diffusive gradient in thin-films (DGT) passive sampling method based on a weak anion exchanger (WAX) binding layer was developed to monitor five PFCAs, five PFSAs, 6:2 FTSA, and GenX in water. Performance was independent of environmental conditions, including pH (3.03-8.96), ionic strength (1-500 mM), and dissolved organic matter content (4-30 mg/L). Diffusion coefficients (D) of the PFAS in the diffusive gels were measured, nine for the first time. Linear correlations between D and perfluoroalkyl chain lengths (CF2) were established to obtain D for congener chemicals with a similar functional group and structure. The binding capacity was at least 440 µg PFAS per sampler, sufficient to apply in water across a wide range of conditions and PFAS concentrations. Successful applications of WAX-based DGT samplers in a wastewater treatment plant and three rivers demonstrated that DGT can be a powerful tool to monitor, surveil and research the 12 PFASs in aquatic systems.

A New Method for the Analysis of PFAS in Non-Potable Water
Zintek, L., W. Lipps, L. Zintek, and D. Kleinmaier.
Environmental Measurement Symposium: Hitting Reset, 2-5 August, Bellevue, WA, 25 slides, 2021

This presentation covers ASTM Committee D19's progress to date in developing and drafting a new method to replace or supplement ASTM Method D7979 to analyze PFAS in non-potable water samples. The method will extract samples in the same manner as D7979, but more compounds are being added along with additional calibration schemes, including isotope dilution. Once developed and optimized, the method will undergo an inter-lab study. The presentation includes chromatography and single laboratory validation and interference studies.

New Passive Sampling Device for PFAS
National Institute of Environmental Health Sciences, Superfund Research Program (SRP), November 2021

A new type of passive sampling device for PFAS that overcomes many limitations to traditional approaches, such as detecting short-chain PFAS and low concentrations of the chemicals in water, was developed. The sampling devices are miniature cylinders assembled from graphene oxide nanosheets, which stack to create internal pores. The cylinders leverage the high internal surface area of the atomically thin graphene to collect PFAS from aquatic environments via adsorption. Concentrated PFAS can then be extracted and measured using traditional laboratory methods. The ability of the cylinders to collect 23 PFAS chemicals from water was measured to explore optimizing the samplers to collect a broader range of PFAS chemicals. An objective was to improve the functionality for sampling short-chain PFAS, which tend to have negative chemical charges and are repelled by the similarly negatively charged graphene oxide nanosheets. Using a novel but simple grafting method based on diazonium chemistry introduced a positive surface charge to the graphene cylinders, increasing their affinity to adsorb short-chain PFAS. Using this modification, a ten-fold increased sorption of short- and middle-chain PFAS was reported. [Additional information]

Passive Sampling of Perfluorinated Chemicals in Water: In-Situ Calibration
Kaserzon, S., D. Hawker, K. Booij, D. O'Brien, K. Kennedy, E. Vermeirssen, and J.F. Mueller.
Environmental Pollution 186:98-103(2014) [Abstract]

A passive modified polar organic chemical integrative sampler (POCIS) was employed to sample PFASs in surface water.

PFAS Analysis in Water for the Global Monitoring Plan of the Stockholm Convention: Set-Up and Guidelines for Monitoring
Weiss, J., J. de Boer, U. Berger, D. Muir, et al.
United Nations Environment Programme (UNEP), Division of Technology, Industry and Economics, 35 pp, 2015

Chapter 4 addresses sampling considerations and guidelines, and Chapter 5 covers analysis, primarily for PFOS.

Spatial, Phase, and Temporal Distributions of Perfluorooctane Sulfonate (PFOS) and Perfluorooctanoate (PFOA) in Tokyo Bay, Japan
Sakurai, T., S. Serizawa, T. Isobe, et al.
Environmental Science & Technology 44(11):4110-4115. 2010. [Abstract]

An investigation was conducted of the behavior of PFOS and PFOA in seawater, especially with regard to stratification and how this affects sampling strategies.

Technology Guidance for Sentinel™ Passive PFAS Samplers Osorb© Media Use in PFAS Passive Samplers
Divine, C. and P. Edmiston. SERDP Project ER20-1127, 25 pp, 2022

This Technical Guidance describes the collection of surface water and groundwater samples using the Sentinel passive sampling device being developed for PFAS in environmental waters. The sampler design is simple and robust, using an organosilica resin modified with cross-linked amine polymer in a high-density polyethylene housing with polypropylene mesh. The addition of amine groups as a weak ion exchange resin in combination with Cu²⁺ was designed to promote binding of short-chain PFAS compounds. Passive sampler uptake rates were relatively constant in lab tests even under extreme ionic strength conditions and natural organic matter concentrations, indicating potential applicability to a wide range of environmental water types. Integrative performance for most analytes showed a linear response to concentration with time (except for perfluorobutanoic acid and perfluoropentanoic acid), simplifying the calculation of aqueous concentrations. Sampling times as short as 3 days were necessary to reach the <70 ng/L detection limits for PFOA and PFOS.

Isomer Profiling

Isomer Profiling of Perfluorinated Substances as a Tool for Source Tracking: A Review of Early Findings and Future Applications
Benskin, J.P., A.O. De Silva, and J.W. Martin.
Reviews of Environmental Contamination and Toxicology 208, P. de Voogt (ed.).
Springer Science, ISBN: 978-1-4419-6880-7_2:111-160(2010)

A particular focus in this chapter is the measurement and interpretation of isomer signatures in the environment to gain new knowledge on emission sources, differentiate between historical versus current exposure sources, or identify direct versus indirect pathways of exposure for humans and wildlife.

Sample Containers

Aqueous Sample Stability: PFOS, PFOA and Other Fluorinated Compounds
Obal, T., A. Robinson, and S.C. Chia.
REMTECH 2012: The Remediation Technologies Symposium, Banff, AB, Canada, 17-19 Oct 2012.
Environmental Services Association of Alberta, Edmonton, AB, 24 slides, 2012

A study to assess preferential adsorption of PFOS, PFOA, and other PFCs in aqueous samples by sample container type reports observed differences in the degree of adsorption and the rate at which adsorption occurs under different sample conditions and in diverse container materials (polypropylene, glass, HDPE, stainless steel). New approaches are recommended to minimize adsorptive effects in aqueous environmental PFC samples.

Bottle Selection and Other Sampling Considerations When Sampling for Per- And Poly-Fluoroalkyl Substances (PFAS) - Revision 1.2
DoD Environmental Data Quality Workgroup, 2 pp, 2017

During sample collection, the use of products that contain PFASs could contaminate the samples. To prevent accidental contamination, this fact sheet identifies materials to use and materials to avoid.

Site Characterization Studies

Application of PFAS-Mobile Lab to Support Adaptive Characterization and Flux-Based Conceptual Site Models at AFFF Releases
Quinnan, J., M. Rossi, P. Curry, M. Lupo, M. Miller, H. Korb, C. Orth, and K. Hasbrouck. Remediation 31(3):7-26(2021) [Abstract]

Two aspects of an ESTCP demonstration that were conducted at Camp Grayling Army Airfield in Grayling, Michigan, are presented. The objective was to demonstrate the value of adaptive high-resolution PFAS site characterization using a quantitative screening method that is selective for PFAS compounds and sensitive across the range of concentrations between screening levels at 40 ng/L and source impacts within the mg/L range. The method's reliability was demonstrated using sample pair comparability statistics with an Environmental Laboratory Accreditation Program-certified lab, visual interpretation of characterization and relative flux, and comparison of contaminant mass discharge calculated at flux transects. In addition, the study measured vadose zone source strength using soil to groundwater concentration ratios, lysimeter porewater sample analysis, and synthetic precipitation leaching procedure testing. Results demonstrated that using the mobile lab and the stratigraphic flux approach can distinguish individual PFAS sources, visually map PFOA and PFOS and migration pathways, and provide an efficient means of ranking source contributions to plumes. Additional information: ESTCP Project

Field-Scale Investigation of Per- and Polyfluoroalkyl Substances (PFAS) Leaching from Shallow Soils to Groundwater at Two Sites in New Hampshire, 2021-2022
Santangelo, L.M., S.M. Welch, A.K. Tokranov, A.F. Drouin, K.E.A. Schlosser, J.M. Marts, T.A. Lincoln, N.A. Deyette, and K. Perkins. U.S. Geological Survey data release, 2023 [Abstract]

PFAS and related chemical and physical data are presented from shallow soil and groundwater sampling conducted at the Brentwood Fire Training Area and White Farm sites in New Hampshire, both known to contain PFAS. Soil samples were collected in a gridded pattern across each site. Soil horizons within the sampling intervals were described using the National Soil Survey Center Natural Resources Conservation Service U.S. Department of Agriculture Field Book for Describing and Sampling Soils. Analyses included 36 PFAS compounds, 36 PFAS compounds post-total oxidizable precursor assay (TOPA), total organic carbon (TOC), moisture content, pH, autoclaved-citrate extractable protein, grain size, major ions, and other physical and physicochemical parameters. Groundwater samples were collected and analyzed for PFAS during two sampling events at each site from temporary wells, existing monitoring wells, and/or pushpoint samplers. Additionally, a lysimeter was installed at the center of each site, and a composite sample through the duration of each water sampling event (~7 days) was collected. Quality control samples included source-solution blanks, equipment blanks, and replicates.

Phytoscreening for Per- and Polyfluoroalkyl Substances at a Contaminated Site in Germany
Wurth, A., M. Mechler, K. Menberg, M.A. Ikipinar, P. Martus, R. Sohlmann, R.S. Boeddinghaus, and P. Blum. Environmental Science & Technology 57(10):4122-4132(2023) [Abstract]

The applicability of phytoscreening was investigated to detect PFAS at a contaminated site in Germany. Foliage of white willow (Salix alba L.), black poplar (Populus nigra L.), and black alder (Alnus glutinosa L.) were sampled to evaluate seasonal and annual variations in PFAS concentrations. Phytoscreening results indicated species and specific differences, with the highest PFAS sum concentrations of Σ23 observed in October for white willow (0-1800 µg/kg), followed by black poplar (6.7-32 µg/kg) and black alder (0-13 µg/kg). The bulk substances in leaves were highly mobile short-chain PFCAs. In contrast, the PFAS composition in soil was dominated by long-chain PFCAs, PFOA and PFDA, as a result of the lower mobility with Σ23PFAS ranging between 0.18 and 26 µg/L (eluate) and between 66 and 420 µg/kg (solid). However, the PFAS composition in groundwater was comparable to the spectrum observed in leaves. Spatial interpolations of PFAS in groundwater and foliage correspond well and demonstrate the successful application of phytoscreening to detect and delineate the impact of PFAS in groundwater.

Remedial Investigation Report: Phase 2 Fluorochemical (FC) Data Assessment Report for the Cottage Grove, MN Site
3M Company, 166 pp, June 2007

An overview is presented by media and area of the findings of the Cottage Grove Site Phase 1 and 2 FC assessments to provide focus on areas of interest for further evaluation as part of the FS process.

Statement of Basis: DuPont Washington Works, Washington, West Virginia
West Virginia Department of Environmental Protection (WVDEP), 28 pp, 2015

This Statement of Basis highlights key [characterization] information relied upon by the WVDEP in making its proposed cleanup decision for PFAS contamination at the DuPont Washington Works.

Subsurface Per- and Polyfluoroalkyl Substances (PFAS) Distribution at Two Contaminated Sites
Schumacher, B., J. Zimmerman, K. Bronstein, R. Warrier, C. Lutes, E. Escobar, and A. Williams. U.S. Environmental Protection Agency, EPA/600/R-23/294, 165 pp, 2023

This investigation represents EPA's initial research into whether the VI exposure pathway is pertinent to PFAS chemicals, with a focus on fluorotelomer alcohols. The investigation was designed to determine whether there is sufficient attenuation (e.g., due to biodegradation) of PFAS vapor concentrations in the vadose zone overlying PFAS-contaminated groundwater or soil to limit or prevent PFAS VI. The study focused on two sites, a PFAS manufacturing plant in New Jersey and a closed, unlined MSW landfill in Georgia, where volatile PFAS were likely present in the soil or uppermost groundwater-bearing zone. The study will inform regulators to help them decide whether VI should be evaluated at the hundreds of sites where PFAS are reasonably expected to have been released to the subsurface and determine what additional research is necessary to evaluate the threat before making policy decisions.

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Analytical Methods

EPA Method 537 is a liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for determining selected perfluorinated alkyl acids (PFAAs) in drinking water (Shoemaker et al. 2009). Additional work has been completed to adapt methods for sewage sludge and biosolids (USEPA 2011) and soil and sediments (Washington et al. 2014). However, Method 537 does not cover all the potential PFAS chemicals that could be present at contaminated sites.

Many PFAS chemicals cannot be analyzed readily due to the lack of appropriate reference materials (Martin et al. 2004; Pancras et al. 2016; Buechler 2016). Additionally, the mixture of linear and branched isomers presents challenges in providing an accurate quantification of many PFASs in environmental matrices (Martin et al. 2004; Buck et al. 2011). EPA Method 537 only calls for the use of branched and linear isomers if standards are available.

There are efforts to develop a total organic fluorine analysis method to detect all the PFAS compounds beyond those in EPA Method 537 (Trojanowicz and Koc 2013). One such method, the total oxidizable precursor (TOP) assay, involves converting all oxidizable PFAS compounds to PFAAs, which can then be detected by a method measuring PFAAs (Houtz and Sedlak 2012). However, it should be noted that this is still limited to what can be oxidized by the method and the limited number of PFAA chemicals in the analytical method. Another method uses particle-induced gamma ray emission (PIGE) to quantify the total amount of fluorine present in a sample (Lang et al. 2016).

An in situ analytical device is under development that utilizes an ion-selective electrode with fluorous anion-exchanger membrane to detect PFOA and PFOS (Chen et al. 2013). Although the detection limits reported were greater than the current drinking water advisory of 70 ppt, this device may serve a role in screening water samples for higher PFOA and PFOS concentrations. As of December 2016 it has not been commercialized.

The presence of certain materials can have an adverse effect on PFAS analytical results. Ahrens et al. (2010) cautions that every material that comes into contact with the sample must be free of fluorinated compounds. Understanding the analytical implications of factors such as PFAS adsorption to surfaces (e.g., containers, filters, tubing), effects of differing matrices, varying PFAS isomer response factors, potential bias effects of sampling, and sample preparation is critical to measuring highly fluorinated compounds at trace levels. These issues and the potential interferences can affect analytical results significantly (Berger et al. 2011).

Research is ongoing for some of these issues, such as the influence of the sample matrix and container type on PFAS loss from the sample. Berger et al. (2011) and Obal et al. (2012) examined the potential effect of sample container material on the recovery of individual PFASs. The Obal et al. (2012) study also found a relationship between PFAS recovery and whether the sample container was partially or completely full.

For discussions of different analytical approaches see Trojanowicz and Koc (2013) and Pancras et al. (2016), including methods under development, such as adsorbable organic fluorinated compounds and total organic fluorine.

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Method Overviews and Reviews

Analytical Methods for Priority and Emerging Contaminants: A Literature Review
Johnston, L.A., M.Y. Croft, and E.J. Murby.
CRC for Contamination Assessment and Remediation of the Environment, Adelaide, Australia. CRC CARE Technical Report No. 24, 118 pp, 2013

Analytical methods and measurement issues for PFOS and PFOA are covered in Section 2.2 and for other PFASs in Section 2.3. The review is limited to lab-based methodology, and does not include field-based testing.

Analytical Methods for the New Proposed Priority Substances of the European Water Framework Directive (WFD)
Loos, R.
European Commission, Joint Research Centre, Institute for Environment and Sustainability, 71 pp, 2012

Pages 37-40 point to standard method ISO 25101, analytical methods applied by EU member states, and analytical methods for PFOS found in the literature.

Challenges in Perfluorocarboxylic Acid Measurements
Larsen, B.S. and M.A. Kaiser.
Analytical Chemistry 79(11):3966-3973(2007)

This article provides background information on C(5) to C(13) PFCAs and discusses the problems that might be encountered when trying to analyze them.

Comparison of Three Types of Mass Spectrometers for HPLC/MS Analysis of Perfluoroalkylated Substances and Fluorotelomer Alcohols
Berger, U., I. Langlois, M. Oehme, and R. Kallenborn
European Journal of Mass Spectrometry 10(5):579-588(2004) [Abstract]

Ion trap MS in the full scan and product ion MS2 mode, time-of-flight high-resolution MS and quadrupole MS in the selected ion mode, and triple quadrupole tandem MS were tested and compared.

Recent Developments in Methods for Analysis of Perfluorinated Persistent Pollutants
Trojanowicz, M. and M. Koc.
Mikrochimica Acta 180(11-12):957-971(2013)

Recent achievements in PFAS determination in various matrices with different methods are described and compared to measurement of total organic fluorine.

Recent Developments in Trace Analysis of Poly- and Perfluoroalkyl Substances
Berger, U., M.A. Kaiser, A. Kaerrman, et al.
Analytical and Bioanalytical Chemistry 400(6):1625-1635(2011) [Abstract]

The potential confounding issues—such as adsorption of PFASs to surfaces, effects of differing matrices, varying PFAS isomer response factors, and potential bias effects of sampling when measuring highly fluorinated compounds at trace levels—are discussed and documented with examples.

Methods for Aqueous Film-Forming Foam

Developing PIGE into a Rapid Field-Screening Test for PFAS
Peaslee, G. SERDP Project ER19-1142, 41 pp, 2020

This project was designed to determine the operating parameters to turn a lab technique known as Particle Induced Gamma-ray Emission Spectroscopy (PIGE) into a field-deployable approach to rapidly screen for the presence of PFAS in groundwaters at AFFF-impacted sites. The precise beam energy of protons required to measure the presence of organic fluorine as a surrogate for PFAS in groundwater that could be produced by modifying a field-deployable accelerator system was determined. Modifications were made to a commercial system's design plans. The method detection limits were estimated based on a series of lab measurements on existing and new solid-phase extraction media. The project showed that the modified system would be theoretically capable of making rapid PIGE measurements (minutes per sample) at a field site. The discovery of an inline filter material that allows PIGE measurement detection limits in the 10-50 ppt range for all anionic PFAS simultaneously indicates the system may be used in various situations to facilitate site characterization, remediation, and long-term monitoring.

Identification of Novel Fluorochemicals in Aqueous Film-Forming Foams (AFFF) Used by the US Military
Place, B. and J.A. Field.
Environmental Science & Technology 46(13):7120-7127(2012) [Abstract]

Fast atom bombardment mass spectrometry (FAB-MS) and high-resolution quadrupole-time-of-flight mass spectrometry (QTOF-MS) were employed to elucidate chemical formulas for the fluorochemicals in AFFF mixtures.

Zwitterionic, Cationic, and Anionic Fluorinated Chemicals in Aqueous Film Forming Foam Formulations and Groundwater from U.S. Military Bases by Nonaqueous Large-Volume Injection HPLC-MS/MS
Backe, W.J., T.C. Day, and J.A. Field.
Environmental Science & Technology 47(10):5226-5234(2013) [Abstract]

Prior to analysis, AFFF formulations were diluted into methanol, and PFAS in groundwater were micro liquid-liquid extracted. Methanolic dilutions of AFFF formulations and groundwater extracts were analyzed by large-volume injection HPLC-MS/MS. Orthogonal chromatography was performed using cation exchange (silica) and anion exchange (propylamine) guard columns connected in series to a reverse-phase (C18) analytical column.

Methods for Aqueous Matrices

Analysis of 18 Perfluorinated Compounds in River Waters: Comparison of High Performance Liquid Chromatography-Tandem Mass Spectrometry, Ultra-High-Performance Liquid Chromatography-Tandem Mass Spectrometry and Capillary Liquid Chromatography-Mass Spectrometry
Onghena, M., Y. Moliner-Martinez, Y. Pico, P. Campins-Falco, and D. Barcelo.
Journal of Chromatography A 1244:88-97(2012) [Abstract]

The performance of UHPLC-MS/MS and CLC-MS for the analysis of 18 perfluorinated compounds in water samples were compared with conventional LC-MS/MS in terms of speed, sensitivity, selectivity and resolution.

Data Review and Validation Guidelines for Perfluoroalkyl Substances (PFASs) Analyzed Using EPA Method 537
Caporale, C., G. Dodo, K. Feddersen, B. Pepich, et al.
EPA 910-R-18-001, 47 pp, 2018

This document contains guidance to aid the data reviewer in determining the usability of analytical data generated for perfluoroalkyl substances. It is primarily based on EPA Method 537 and the general validation approach developed under EPA's Contract Laboratory Program. The guide is intended to be applicable to data gathered using EPA Method 537 for investigative purposes.

Determination of Selected Perfluorinated Alkyl Acids in Drinking Water by Solid Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS)
Shoemaker, J.A., P.E. Grimmett, and B.K. Boutin.
EPA600-R-08-092, EPA Method 537, Rev 1.1, 50 pp, 2009

Discovery of C5-C17 Poly- and Perfluoroalkyl Substances in Water by In-Line SPE-HPLC-Orbitrap with In-Source Fragmentation Flagging
Liu, Y., A. Dos Santos Pereira, and J.W. Martin.
Analytical Chemistry 87(8):4260-4268(2015) [Abstract]

The studied method for analyzing PFASs in water was validated by applying it to an industrial wastewater; 36 new PFASs were discovered during the process.

Fluorous Membrane Ion-Selective Electrodes for Perfluorinated Surfactants: Trace-Level Detection and in Situ Monitoring of Adsorption
Chen, L.D., C.-Z. Lai, L.P. Granda, M.A. Fierke, D. Mandal, A. Stein, J.A. Gladysz, and P. Buehlmann.
Analytical Chemistry 85(15):7471-7477(2013) [Abstract]

Ion-selective electrodes (ISEs) with fluorous anion-exchanger membranes were developed for the potentiometric detection of PFOA and PFOS. To demonstrate a real-life application of these electrodes, in situ measurements were performed of PFOS adsorption onto Ottawa sand (a standard sample often used in environmental sciences) and in a background of water from Carnegie Lake. Additional information: NSF Grant 1256626

Oxidative Conversion as a Means of Detecting Precursors to Perfluoroalkyl Acids in Urban Runoff
Houtz, E.F., and D.L. Sedlak.
Environmental Science & Technology 46(17):9342-9349(2012) [Abstract]

This article discusses a method to quantify concentrations of unidentified precursors of perfluoroalkyl carboxylic (PFCA) and sulfonic (PFSA) acids in urban runoff. The method transforms perfluoroalkyl acid (PFAA) precursors to PFCAs of related perfluorinated chain length.

Perfluorooctanoic Acid (PFOA) in Drinking Water
Federal-Provincial-Territorial Committee on Drinking Water.
Health Canada, 103 pp, 2016

Chapter 6 discusses available methods for drinking water, analytical challenges, and analytical performance.

A Validated Analytical Method for the Determination of Perfluorinated Compounds in Surface-, Sea- and Sewage Water Using Liquid Chromatography Coupled to Time-of-Flight Mass Spectrometry
Wille, K., J. Vanden Bussche, H. Noppe, E. De Wulf, P. Van Caeter, C.R. Janssen, et al.
Journal of Chromatography A 1217(43):6616-6622(2010)

The target analytes were extracted using solid-phase extraction followed by LC-ToF-MS. The use of very narrow mass tolerance windows (<10 ppm) resulted in a highly selective MS technique for the detection of PFCs in complex aqueous matrices.

Water Quality: Determination of Perfluorooctanesulfonate (PFOS) and Perfluorooctanoate (PFOA), Method for Unfiltered Samples Using Solid Phase Extraction and Liquid Chromatography/Mass Spectrometry
International Organization for Standardization (ISO), ISO 25101, 2009 [Abstract]

Methods for Human Serum

A Fast Method for Analysing Six Perfluoroalkyl Substances in Human Serum by Solid-Phase Extraction On-Line Coupled to Liquid Chromatography Tandem Mass Spectrometry
Bartolome, M., A. Gallego-Pico, O. Huetos, M.A. Lucena, and A. Castano.
Analytical and Bioanalytical Chemistry 408(8):2159-2170(2016) [Abstract]

An online TurboFlow solid-phase extraction procedure was coupled to HPLC-MS/MS for analysis of PFOS, PFOA, perfluorohexane sulfonate, perfluorononanoic acid, perfluorodecanoic acid, and N-methylperfluorooctane sulfonamide in human serum samples.

Online Solid Phase Extraction-High Performance Liquid Chromatography-Turbo Ion Spray-Tandem Mass Spectrometry (online SPE-HPLC-TIS-MS/MS)
Centers for Disease Control and Prevention, CDC Method 6304.04, 42 pp, 2013

Laboratory procedures are provided for 12 polyfluoroalkyl chemicals in a serum matrix: perfluorooctane sulfonamide, 2-(N-methyl-perfluorooctanesulfonamido) acetate, 2-(N-ethyl-perfluorooctanesulfonamido) acetate, perfluorobutane sulfonate, perfluorohexane sulfonate, perfluorooctane sulfonate, perfluoroheptanoate, perfluorooctanoate, perfluorononanoate, perfluorodecanoate, perfluoroundecanoate, and perfluorododecanoate.

Methods for Multiple Matrices

Decades-Scale Degradation of Commercial, Side-Chain, Fluorotelomer-Based Polymers in Soils and Water
Washington, J.W., T.M. Jenkins, K. Rankin, and J.E. Naile.
Environmental Science & Technology 49(2):915-923(2015) [Abstract]

This report describes a 376-day study of the degradability of two commercial acrylate-linked FTPs in four saturated soils and in water. The study employed an exhaustive serial extraction procedure with GC/MS and LC/MS/MS results for 50 species, including fluorotelomer alcohols and acids and perfluorocarboxylates.

Determination of Extractable Perfluorooctanesulphonate (PFOS) in Coated and Impregnated Solid Articles, Liquids and Fire Fighting Foams: Method for Sampling, Extraction and Analysis by LC-qMS or LC-tandem/MS
European Committee for Standardization (CEN), CEN/TS 15968, 2010 [Abstract]

Determination of Perfluoroalkyl Carboxylic, Sulfonic, and Phosphonic Acids in Food
Ullah, S., T. Alsberg, R. Vestergren, and U. Berger.
Analytical and Bioanalytical Chemistry 404(8):2193-2201(2012) [Abstract]

A method is described for simultaneous analysis of perfluoroalkyl carboxylic acids, sulfonic acids, and phosphonic acids at low picograms per gram concentrations in a variety of food matrices. [Additional information]

Determination of Perfluoroalkyl Compounds in Water, Sediment, and Biota
Ahrens, L., K. Vorkamp, P. Lepom, et al.
International Council for the Exploration of the Sea, ICES Techniques in Marine Environmental Sciences No. 48, 16 pp, 2010

An overview is provided of environmentally relevant PFCs and techniques for their analysis in samples of water, sediment, and biota, including sampling, pretreatment, extraction, cleanup, instrumental analysis, quantification and quality assurance, and quality control.

Focused Ultrasound Solid-Liquid Extraction for the Determination of Perfluorinated Compounds in Fish, Vegetables and Amended Soil
Zabaleta, I., E. Bizkarguenaga, A. Iparragirre, P. Navarro, A. Prieto, et al.
Journal of Chromatography A 1331:27-37(2014) [Abstract]

A method is described for the determination of different perfluorinated compounds, including three perfluorinated sulfonic acids, seven perfluorocarboxylic acids, three perfluorophosphonic acids, and PFOSA in fish, vegetables and amended soil samples, using focused ultrasound solid-liquid extraction followed by SPE cleanup and LC-MS/MS.

Multi-Laboratory Validation Study for Analysis of PFAS by EPA DRAFT Method 1633
Willey, J., A. Hanley, R. Anderson, A. Leeson, and T. Thompson. SERDP Project ER19-1409, 2024

The overarching goal of this project conducted by the DoD and EPA was to establish a standardized analytical method for PFAS in various environmental matrices, including groundwater, surface water, soils, sediment, landfill leachate, municipal wastewater, tissue, and biosolids (i.e., municipal wastewater treatment plant residuals). A single-laboratory study and a multi-laboratory study were completed with a focus on generating the necessary data to document the precision and accuracy of the analytical method for quantitation of PFAS in environmental media. The lab validation study was conducted as a single-lab validation before a multi-lab validation was conducted. The multi-lab study was conducted in several phases:

• Validation for wastewater, surface water, and groundwater (Volume I) (Volume I Appendices )
• Soils and Sediments (Volume II)
• Landfill Leachates and Biosolids (Volume III)
• Tissue (Volume IV)

The results for all reports but the landfill leachates support the finding that EPA Method 1633 measures PFAS concentrations as well as or better than most EPA methods for similar-sized organic contaminants in real-world samples of these matrices. The landfill leachate results demonstrate the ability of the method to adequately measure PFAS concentrations in real-world landfill leachate and biosolids samples. However, the mean % recovery of PFDoS (48.9%) in spiked biosolid samples across all six labs indicated recovery of this analyte in biosolids samples may be biased low. Ongoing precision and recovery standards (OPR) and low-level OPR (LLOPR) data associated with biosolids sample results for PFDoS should be considered when determining the usability of biosolids sample data for PFDoS.

Single-Laboratory Validation Study of PFAS by Isotope Dilution LC-MS/MS
Willey, J., R. Anderson, A. Hanley, M. Mills, C. Hamilton, T. Thompson, and A. Leeson. SERDP Project ER19-1409, 570 pp, 2022

An analytical method for the preparation and analysis of PFAS in environmental matrices was validated in a joint effort by the DoD and EPA. The study was designed to provide data on the accuracy and precision of the method in aqueous matrices (wastewater, surface waters, groundwaters, landfill leachate), solids (soil, sediment, biosolids), and fish and clam tissues. The standard operating procedure (SOP) and the results of the study were the basis for EPA's Office of Water draft Method 1633: Analysis of Per- and Polyfluoroalkyl Substances (PFAS) in Aqueous, Solid, Biosolids, and Tissue Samples by LC-MS/MS, published in September 2021. Method efficacy was evaluated using a mean matrix spike interim recovery criterion of 70-130% of the spike concentration after correcting for native sample concentrations. The method is being tested further in a multi-laboratory validation study that will be completed in 2022.

Standard Test Method for Determination of Perfluorinated Compounds in Water, Sludge, Influent, Effluent and Wastewater by Liquid Chromatography Tandem Mass Spectrometry (LC/MS/MS): ASTM D7979-16
ASTM International, West Conshohocken, PA, 2016 [Abstract]

This method has been investigated for use with reagent, surface, sludge and wastewaters for selected perfluorinated compounds. However, this method has not undergone multilaboratory validation.

Single-Laboratory Validation Study of PFAS by Isotope Dilution LC-MS/MS
Quinnan, J., P. Curry, M. Lupo, M. Miller, and M. Rossi. ESTCP Project ER19-5203, 242 pp, 2021

The objectives of this project were to demonstrate the application of three real-time mobile laboratory methods to analyze PFAS, including a standard DoD Quality Systems Manual approach, an accelerated liquid chromatography tandem mass spectroscopy method for quantitative screening, and a methylene blue active substances semiquantitative screening approach. The methods were applied using high-resolution site characterization and a stratigraphic flux to map PFAS migration pathways using a relative flux heat map. Soil to groundwater concentration ratios, lysimeter pore water sampling, and synthetic precipitate leaching procedures were used to evaluate source strength.

Methods for Solid Matrices

Analysis of Perfluorinated Carboxylic Acids in Soils II: Optimization of Chromatography and Extraction
Washington, J.W., W.M. Henderson, J.J. Ellington, T. Jenkins, and J.J. Evans.
Journal of Chromatography A 1181(1-2):21-32(2008) [Abstract]

This study compared the analytical suitability of liquid chromatography columns containing three different stationary phases, two different liquid chromatography tandem mass spectrometry (LC/MS/MS) systems, and eight combinations of sample-extract pretreatments, extractions and cleanups on three test soils.

Characterizing Fluorotelomer and Polyfluoroalkyl Substances in New and Aged Fluorotelomer-BasedPolymers for Degradation Studies with GC/MS and LC/MS/MS
Washington, J.W., J.E. Naile, T.M. Jenkins, and D.G. Lynch.
Environmental Science & Technology 48(10):5762-5769(2014) [Abstract]

The authors report a method for quantitating fluorotelomer-based polymers (FTPs) to yield internally consistent accounting of monomers and associated compounds for FTPs, either alone or in a soil matrix, for both new and simulated-aged FTPs to allow degradation testing, and for fluorinated compounds at least as long as C12.

Determination of Ten Perfluorinated Compounds in Sludge Amended Soil by Ultrasonic Extraction and Liquid Chromatography-Tandem Mass Spectrometry
Garcia-Valcarcel, A., E. Miguel, and J.L. Tadeo.
Analytical Methods 4(8):2462-2468(2012) [Abstract]

A method for the analysis of five perfluoroalkyl carboxylates, three perfluoroalkyl sulfonates, and two perfluoroalkyl sulfonamides uses ultrasound-assisted extraction followed by a dispersive solid-phase extraction cleanup and analysis by LC-MS/MS.

Method Development for Analysis of Short- and Long-Chain Perfluorinated Acids in Solid Matrices
Li, F., C. Zhang, Y. Qu, J. Chen, X. Hu, and Q. Zhou.
International Journal of Environmental Analytical Chemistry 91(12):1117-1134(2011) [Abstract]

The presented method consists of solvent extraction of PFAs from solid matrices using sonication, solid-phase extraction using weak anion exchange cartridges, cleanup of SPE eluent with dispersive carbon sorbent, and quantitation by HPLC-negative ESI-MS/MS.

Optimization and Comparison of Several Extraction Methods for Determining Perfluoroalkyl Substances in Abiotic Environmental Solid Matrices Using Liquid Chromatography-Mass Spectrometry
Lorenzo, M., J. Campo, and Y. Pico.
Analytical and Bioanalytical Chemistry 407(19):5767-5781(2015) [Abstract]

Four methods for extracting PFASs from soils and sediments were compared to determine the one that provides the best recoveries and the highest sensitivity.

Re-investigation of Aerobic Biodegradation of 6:2 and 8:2 Polyfluroalkyl Phosphate Diesters (6:2 and 8:2 diPAPs) in Soil
Liu, C. and J. Liu.
11th Annual Workshop on LC/MS/MS Applications in Environmental Analysis and Food Safety, September 21-22, 2015, Burlington, ON. [Abstract, page 36 ]

During an investigation of the environmental fate of 6:2 diPAP and 8:2 diPAP in soils, soil extraction methods were found to have a great impact on study outcome. Some commonly used extraction methods either did not recover the PAPs efficiently or caused substantial solvent-enhanced hydrolysis that biased study results.

Standard Test Method for Determination of Polyfluorinated Compounds in Soil by Liquid Chromatography Tandem Mass Spectrometry (LC/MS/MS): ASTM D7968-17
ASTM International, West Conshohocken, PA, 2017 [Abstract]

This method has been used to determine selected polyfluorinated compounds in sand and four ASTM reference soils. However, this method has not undergone multilaboratory validation.

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