PFAS TESTING METHODS
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PFAS testing is not one-size-fits-all. Different projects call for different methods, depending on the compounds you care about, the matrices you need tested, and the regulatory programs you must satisfy. On this page, you’ll find an overview of the leading PFAS test options available through Pace®, from targeted compound analysis to screening tools like total fluorine and precursor assays, along with guidance to help you match each method to your objectives.
THERE ARE MANY PFAS TESTING METHODS AVAILABLE FOR ANALYZING PFAS. WHICH ONE IS “BEST” DEPENDS ON YOUR PROJECT PARAMETERS AND GOALS.
Jump to Test Method:
AOF/EPA 1621
MATRICES: AQUEOUS
In PFAS Testing, AOF/EPA 1621 measures adsorbable organic fluorine in non-potable water. EPA 1621 utilizes combustion ion chromatography (CIC) instrumentation. The EPA intends EPA 1621 to be utilized as a screening tool to assess organic fluorine concentrations in non-potable water, which often contains many PFAS compounds not detectable by targeted methods such as EPA 1633. The EPA Office of Water describes EPA 1621 as a “Screening Method for the Determination of Adsorbable Organic Fluorine (AOF) in Aqueous Matrices by Combustion Ion Chromatography (CIC).” Its reporting limit is in the single-digit parts-per-billion range. Pace® was chosen to perform the single-lab validation for EPA 1621.
ASTM D8421/ASTM D8535/EPA 8327
MATRICES: GROUND & SURFACE WATERS, WASTEWATER, LANDFILL LEACHATE, BIOSOLIDS, SOIL & SEDIMENT
ASTM D8421 and D8535 are PFAS testing methods developed by the American Society for Testing and Materials (ASTM) to provide a definitive method for PFAS analyses in aqueous and solid matrices, respectively. ASTM D8421/D8535 utilizes Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS), with optional uses of Isotope Dilution (ID) to minimize the impacts of sample matrix interference on quantification and thus improve data quality. Technically similar to EPA 8327, Pace® can cite either EPA 8327 or ASTM D8421/D8535.
ASTM D8421/D8535 and EPA 8327 PFAS testing methods offer several advantages over other methods. Turnaround time (TAT) is faster than other published methods that are more procedurally challenging. With optimal procedural requirements, ASTM D8421/D8535/EPA 8327 can also be delivered at a lower price point than other PFAS methods. Finally, ASTM D8421/EPA 8327 only requires 15 mL of water volume to be collected. Therefore, this saves significant field collection time and shipping costs compared to other methods, such as EPA 1633, which require higher sample volumes. Along with EPA 1633, the DOD utilizes ASTM methods to expedite base-wide remedial investigations across the country.
Consumer and Industrial Products
MATRICES: TEXTILES, FOOD CONTACT MATERIALS, AND MANY OTHER CONSUMER AND INDUSTRIAL PRODUCTS
PFAS is often an ingredient in consumer products and other materials used for packaging and in many commercial and industrial applications. It is also a concern in the container industry and chemical formulation. Pace® utilizes EPA Method 1633 with cryomilling to analyze for common PFAS compounds in consumer and industrial products. Also, we offer Total Fluorine by CIC for these products.
EPA 1633
MATRICES: WASTEWATER, SURFACE WATER, GROUNDWATER, SOILS, BIOSOLIDS, BIOLOGICAL TISSUES, LANDFILL LEACHATE, AND SEDIMENT
EPA 1633 can quantitate PFAS compounds across a wide range of solid and aqueous matrices. This method will replace all laboratory-specific SOPs over time and play a vital role in the EPA’s efforts to study, monitor, and regulate PFAS in nearly all matrices and regulatory programs except drinking water. In addition to other methods, including ASTM D8421 and ASTM D8535, the DOD utilizes EPA 1633 for remedial investigations at military sites across the country.
Pace® participated in the multi-lab validation of this method. This method will be adopted into SW-846 for the RCRA program and promulgated under 40 CFR Part 136. Pace® labs are also DOD-certified for EPA 1633.
EPA 537.1
MATRIX: DRINKING WATER
An EPA validated method, EPA 537.1 was developed to replace EPA 537 and is common in drinking water compliance. In addition to analyzing for the 14 compounds, which covers the original EPA 537 PFAS testing method, EPA 537.1 also analyzes for four replacement PFAS: 11Cl-PF3OUdS 9Cl-PF3ONS, ADONA, and HFPO-DA (also known as Gen X).
EPA 533
MATRIX: DRINKING WATER
EPA 533 expanded the number of PFAS compounds that can be analyzed in drinking water samples. Unlike the 537 series, this method utilizes isotope dilution, providing additional quality control for accuracy of reporting, especially at ppt (parts per trillion) levels. EPA 533 does not replace EPA 537.1, but together, the tests analyze for 29 PFAS compounds. EPA 533 is also commonly used for drinking water compliance, and both EPA 533 and EPA 537.1 are a requirement for UCMR 5 compliance.
PACE® IS AN APPROVED UCMR 5 TESTING LABORATORY. YOU CAN LEARN MORE ABOUT THE PROGRAM AND OUR SERVICES ON OUR UCMR 5 PROGRAM PAGE.
PFAS by Isotope Dilution
MATRICES: GROUND & SURFACE WATERS, WASTEWATER, LANDFILL LEACHATE, WASTEWATER SLUDGE & BIOSOLIDS, SOIL & OTHER SOLIDS, BIOTA, AFFF
Like many commercial labs, Pace® developed and validated an isotope dilution method based on EPA 537 to apply for non-drinking water matrices such as non-potable water, solids, biota, and biosolids. This method is widely applicable to both DOD and commercial/industrial applications. Furthermore, Pace® has been audited and certified to the accreditation standards of DOD, TNI NELAC, and state accreditation bodies for this method.
TOP Assay
MATRICES: AQUEOUS AND SOLIDS
PFAS precursors, both known and unknown, are a class of PFAS compounds that can degrade to terminal PFAS compounds (i.e., perfluoroalkyl substances) under the right environmental circumstances. TOP Assay oxidizes PFAS precursors, most of which are compounds not currently measured by targeted techniques, converting them into their terminal PFAS compounds that can then be measured. The increase in PFAS measuring after the TOP Assay oxidation relative to pre-oxidation levels is a gross estimate of the total concentration of PFAS precursors present in a sample. PFAS testing and analysis by TOP Assay is particularly useful in forensic studies designed to identify the source of increasing PFAS levels in all matrices.
Total Fluorine/Total Organic Fluorine
MATRICES: CONSUMER AND INDUSTRIAL PRODUCTS
Total Fluorine is one of the more common test methods used for analyzing PFAS in matrices such as consumer goods. At its essence, the method employs combustion (>1000°C) to liberate all organic and inorganic fluoride into a hydrogen fluoride (HF) gas. The HF is then directed into an aqueous solution that can be quantified by ion chromatography (IC). Collectively, this instrument is known as combustion/IC, or CIC.
This test method does not distinguish between organic and inorganic fluorine/fluoride. Therefore, the presence of any fluorine-containing compounds, such as sodium fluoride or calcium fluoride, will be included in the total fluorine result. However, this is still a powerful tool because of its relative simplicity, coupled with the fact that if the Total Fluorine level is below a certain threshold, then the more commonly referenced Total Organic Fluorine is also below that level.
PFAS Testing FAQs
Q: What is the difference between targeted PFAS and non targeted PFAS?
Targeted PFAS are the well-characterized‑ compounds that appear on regulatory or laboratory analyte lists. Analytical methods for targeted PFAS are developed around commercially available reference standards, enabling laboratories to measure each compound with a high degree of confidence and report a precise concentration.
Nontargeted PFAS are everything outside that list, e.g., suspected, emerging, precursors, and unknown fluorinated compounds that may be present but for which available standards or formal method coverage is not yet available. EPA 1621 can be used to scan for thousands of fluorinated compounds to provide an approximate view of the PFAS “universe” in a sample.
Q: What is a PFAS Screening Method?
A screening method is typically used when the goal is to understand whether any PFAS contamination exists, how broad the PFAS mixture might be, or whether additional, nontargeted PFAS could be present beyond a standardized test method list—for example, in early site investigations, source identification, or prioritizing locations or samples for more detailed follow-up testing. EPA 1621, which measures adsorbable organic fluorine (AOF), is a good example: It does not identify individual PFAS compounds but can rapidly flag water or wastewater samples that contain elevated organic fluorine and therefore warrant more detailed targeted analyses.
While the U.S. EPA developed EPA 1621 as a screening method, keep in mind that other “targeted methods” may also be used for screening purposes. For example, EPA 1633A may be used as a screening method for drinking water samples alongside EPA 533 and EPA 537.1 for compliance reporting. Targeted methods, including EPA 1633A and ASTM D8421, can also be used for screening purposes, although these methods quantitate a defined list of individual PFAS compounds, rather than providing a bulk/total fluorine or screening-only measurement.
Q: Why should I test for PFAS that aren’t regulated?
Testing for unregulated PFAS provides a clearer picture of overall PFAS exposure, helps identify emerging risks early, and allows utilities and industry to prepare for future regulations that may affect liability, treatment costs, and public perception. One primary concern is the thousands of PFAS precursors, such as 6:2 FTS and 8:2 FTS, that have been shown to transform into terminal regulated PFAS under certain conditions.
In addition, many unregulated PFAS share similar persistence, mobility, and potential toxicity characteristics with regulated compounds, leading regulatory agencies to increasingly focus on broader PFAS classes and mixtures. Monitoring data for unregulated PFAS, including shorter-chain acids, such as PFPeA and PFHxA, can inform risk evaluations as these substances are frequently detected in public water systems and other environmental media.
Finally, understanding the complete PFAS profile, including precursors and unregulated compounds, supports better design and optimization of treatment systems, such as activated carbon, ion exchange, and high-pressure membranes. If treatment planning focuses only on regulated PFAS, systems can underestimate total PFAS loading, shorten media life, and miss opportunities to address upstream sources. Conversely, more comprehensive testing helps align investments with the true PFAS burden and long-term compliance needs.
Q: Can we use EPA 1633A to analyze PFAS in drinking water samples?
For compliance reporting, the U.S. EPA and state regulatory agencies require EPA 533 or 537.1. These methods have been validated by the U.S. EPA for regulatory compliance monitoring under the Safe Drinking Water Act (SDWA). EPA 1633A was developed mainly for other aqueous and solid environmental matrices (such as wastewater, surface water, groundwater, leachate, soil, sediment, and biosolids) under the Clean Water Act, so it is not accepted for formal drinking water compliance reporting.
However, laboratories and utilities may use EPA 1633A for noncompliance, investigative monitoring of drinking water to screen for PFAS and assess potential issues before or alongside regulated testing. EPA 1633A can be implemented at a lower cost than the total of the two drinking water methods, making it a more economical way to perform broader or more frequent screening for non-compliance purposes.
Q: What is isotope dilution?
In PFAS analysis, isotope dilution greatly improves accuracy and compensates for analyte losses and matrix interference during extraction and LCMS/MS measurement. In this approach, a known amount of an isotopically labeled analog of each target PFAS is added to the sample before analysis, and the ratio of the native PFAS signal to its labeled analog is used to calculate the PFAS concentration.
Because of the ability to correct for variability and sample interference, isotope dilution is key to several analytical methods, including EPA 533 and EPA 1633A. These methods rely on extracted isotope-labeled internal standards to produce more reliable PFAS measurements in complex matrices like drinking water, wastewater, and environmental solids.
Q: Do any of the test methods analyze for short-chain PFAS and ultra-short-chain PFAS?
To provide a level set, let’s start by defining terms. Short-‑chain PFAS are usually defined as compounds with about four to seven fully or mostly fluorinated carbons, while ultra-short‑-‑chain PFAS have fewer than four carbons. These smaller PFAS are more polar and mobile than long-chain PFAS, which makes them more difficult to measure with standard methods. Because of this, many regulatory methods focus on C4+ PFAS, although development is underway to design or enhance methods for the analysis of ultra-short-chain PFAS.
Of the two EPA-validated drinking water methods, EPA 533 and EPA 537.1, only EPA 533 performs well with short-chain PFAS. This is one of the reasons both of these methods were required for UCMR 5 sampling. However, neither EPA 533 nor EPA 537.1 is validated for ultra-short chain PFAS with fewer than four carbons.
EPA 1621 is a screening method for adsorbable organic fluorine (AOF). The method reports total organic fluorine retained on granular activated carbon but does not target individual PFAS compounds. Because short-chain organic fluorine compounds are poorly retained on the carbon sorbent used, EPA 1621 does not reliably include ultra-short-chain PFAS in its assessment for total organic fluorine.
EPA 1633A, used for non-potable water and other matrices, targets around 40 named PFAS, including several short-chain PFAS in the C4-C6 range. While EPA 1633A (as published) was not validated to include ultra-short-chain PFAS below C4, Pace® has validated and thus added a few ultra-short-chain PFAS, including PFPrA and TFSI, to its EPA 1633A analyte list.
ASTM D8421 is designed to measure an extensive list of PFAS in aqueous samples, including short-chain‑ PFAS down to at least C3. While ASTM D8421 is not currently specified for PFAS compliance reporting, it has some advantages over more procedurally complex methods, such as EPA 1633A. Furthermore, the U.S. EPA has begun the process of adding ASTM D8421 to its official list of approved methods through a Clean Water Act Methods Update Rule (MUR). Once finalized, this rule would place ASTM D8421 in the regulatory tables under 40 CFR Part 136, making it an approved alternative for PFAS analysis in appropriate wastewater and other CWA programs.
Q: Do I need to be careful about cross-contamination when collecting samples for PFAS analysis?
Cross contamination is a concern in PFAS sampling because PFAS are present in many everyday products and materials used in the field. During sample collection and handling, avoid PFAS-containing items such as waterproof clothing, markers, sunscreens, and fluoropolymer-based gear; use appropriate blanks (field, equipment, and trip blanks) to check for contamination; and follow strict sampling protocols to keep sample containers, equipment, and preservatives clean and PFAS-free.
Learn more about how to avoid PFAS sample cross-contamination.
Q: What new PFAS test methods are under development by the U.S. EPA or other organizations?
While tremendous work on PFAS test methods has been completed in the last few years, new methods and techniques are always under development. Advancements in the current PFAS analytical toolbox will be required to fully understand and address the extent of PFAS in the environment, treated drinking water, and consumer and industrial products.
Method development work includes adding additional short‑ and ultra‑short‑chain PFAS, fluorinated acids, and sulfonates to future drinking water and groundwater methods. EPA recently presented high-level details on two evolving drinking water methods: Method 534 and Method 563. Method 534 is a direct‑injection method for nine compounds that is expected to be published soon given that a multi-lab study has been completed. Method 563 focuses on ultra-short compounds and will likely be finalized in 2026.
In parallel with these targeted methods, EPA, ASTM, and other groups are refining “total PFAS” style tools such as extractable organic fluorine (EOF), total organic fluorine (TOF), and the Total Oxidizable Precursor (TOP) Assay. These approaches are especially useful for analyzing complex matrices—such as groundwater, surface water, leachate, and wastewater—in which thousands of PFAS and their precursors may be present, and they help fill important gaps that compound‑specific methods alone cannot fully address.
Q: We’re conducting a site assessment at a potential CERCLA Superfund site located on bedrock with only a thin soil cover. How does PFAS sampling in bedrock differ from PFAS sampling in soil?
PFAS sampling in bedrock needs to focus on how contaminants move and are stored in the rock, not just in the thin overburden. COREDFN is a high-resolution bedrock characterization approach that evaluates contaminant mass in both fractures and the rock matrix, helping to identify‑ which fractures are true transport pathways and how much PFAS is stored in otherwise “immobile” zones. For years, COREDFN has been used to analyze numerous common contaminants in bedrock. More recently, Sanborn Head, the team at Morwick G360, and Pace® adapted COREDFN sampling and testing methodologies for PFAS.
REASONS TO CHOOSE PACE®
EXPERIENCED
Pace® has been an industry leader in persistent organic pollutant testing for over three decades.
CERTIFIED
We’re certified/accredited by NELAC, ISO, DOD, DOE, and in every state with a PFAS lab certification program.
RELIABLE
For emergencies, our Rapid Response Team can provide defensible results in as little as 24 hours.
COMMITTED
We are committed to helping our customers advance their important work through building strong relationships, delivering upon expectations, and providing exceptional customer service.
ADVANCED
We can test for PFAS in both solid and aqueous matrices, including potable and non-potable waters, soils, and biota.
INNOVATIVE
We’re on the leading edge of science, working with EPA, DOD, ASTM, and others to develop new methods for analyzing PFAS.
