What is PFAS testing? Lab methods, standards, kits and what drives the cost

What PFAS testing measures

PFAS testing is a lab measurement of per- and polyfluoroalkyl substances, a family the EPA counts in the thousands. The OECD definition counts any substance with at least one fully fluorinated methyl (CF3) or methylene (CF2) carbon. The EPA’s TSCA reporting rule uses a narrower definition, so one molecule can be a PFAS under one and not the other.

No method measures every PFAS. Labs answer the question in two ways:

• Targeted analysis names and quantifies a fixed list of compounds, usually by LC-MS/MS. Each compound gets its own result: ng/L (parts per trillion) for water, ng/g or ng/kg for solids and food.
• Organic fluorine screens measure the fluorine bound to carbon in a sample. They catch compounds no list includes, but they cannot say which compounds are there.

A full picture often needs both.

PFAS testing methods: targeted LC-MS/MS

In a targeted method, the lab first adds isotope-labelled copies of the target compounds to the sample. Solid-phase extraction (SPE) concentrates the PFAS from 100 to 250 mL of water into 1 mL (Method 533). Liquid chromatography separates the compounds, and a tandem mass spectrometer identifies each by its mass transitions and retention time. Because the labelled copies go through every step, the results are corrected for losses and, in part, for matrix effects. Method 1633A calls this isotope dilution.

In single-lab studies, the lowest concentration minimum reporting levels were 0.53 to 6.3 ng/L for Method 537.1 and 1.4 to 16 ng/L for Method 533. ISO 21675 states that a limit of quantification of 0.2 ng/L can be reached for most of its compounds, and that the real limit depends on each lab’s blanks.

PFAS testing standards by sample type

Method	Sample type	Compounds	How it works
EPA 537.1 (2018; version 2.0, 2020)	Drinking water	18 PFAS	SPE, LC-MS/MS, internal standards
EPA 533 (2019)	Drinking water	25 PFAS	Isotope dilution, anion-exchange SPE, LC-MS/MS
EPA 8327 (2019)	Groundwater, surface water, wastewater	24 PFAS	LC-MS/MS, external standard calibration
EPA 1633A (December 2024)	Wastewater, surface water, groundwater, soil, biosolids, sediment, landfill leachate, fish tissue	40 PFAS	Isotope dilution, LC-MS/MS
ISO 21675:2019	Drinking, fresh, sea and waste water with under 2 g/L of suspended solids	The list in the standard, which may be modified	SPE, LC-MS/MS
FDA C-010.03 (posted April 2024)	Food and feed	30 PFAS	QuEChERS and SPE, LC-MS/MS
EPA 1621 (January 2024)	Water, such as wastewater	One total: adsorbable organic fluorine	Combustion ion chromatography

Each list is fixed. Method 533 reaches down to PFBA, an acid with four carbons. Method 537.1 adds longer ones such as PFTrDA and PFTA. So the EPA’s national drinking water survey, UCMR 5, used both methods to cover 29 PFAS. Ateia et al. (2023) note that labs may add compounds, but only as far as certified reference standards exist.

Most compounds have a second, confirming mass transition. FDA’s food method warns that bile acids in eggs, seafood, milk and meat produce the main PFOS transition and can cause false positives. PFBA and PFPeA have only one transition, so the FDA confirms any positive for them by high-resolution mass spectrometry.

Forever chemicals testing beyond a fixed list

Targeted lists miss precursors and newer compounds, so the PFAS a targeted method measures may be only part of what a sample holds (Ateia et al.). Screens fill the gap, each with its own limits.

Approach	What it measures	What it cannot tell you
AOF, EPA Method 1621	Organic fluorine that binds to activated carbon, measured by combustion ion chromatography (CIC)	Which compounds are present. It works at the part-per-billion (µg/L) level and also counts fluorinated pesticides and pharmaceuticals
EOF and TOF by CIC	Organic fluorine a solvent extracts (EOF), or all of it (TOF); AOF and EOF are both parts of TOF	The extraction decides what counts; common procedures often miss ultrashort-chain PFAS
TOP assay	A targeted run on two portions, one oxidised with heat-activated alkaline persulfate; the rise in PFAS acids estimates hidden precursors	Oxidation can form TFA and PFPrA, which most targeted methods do not measure
Non-target screening by high-resolution MS	Thousands of possible PFAS, by exact mass	Amounts without matching standards; the authors call it resource-intensive expert work, not routine testing
19F NMR	Total PFAS from the terminal CF3 signal, TFA included	Low levels: the 2023 method’s detection limit was 50 µg/L, far above LC-MS/MS

In one wastewater sample in the 2023 NMR study (Camdzic et al.), TFA (trifluoroacetic acid) came to more than five times the total PFAS that LC-MS measured. TFA is an ultrashort-chain PFAS acid with two carbons, and it matters for peptides.

The PFAS testing process, from bottle to report

1. Match the method to the sample and purpose. A result for a regulator needs the method the rule names. Soil, sludge or wastewater points to Method 1633A.
2. Use the lab’s containers. Method 1633A bans PTFE-lined caps and requires each lot of bottles to be shown PFAS-free. Method 537.1 uses a 250 mL polypropylene bottle that already holds its preservative, Trizma.
3. Add a field reagent blank. A bottle of PFAS-free water from the lab travels with the samples and is opened on site. It shows whether shipping, storage or the site added PFAS.
4. Ship cold. Method 533 samples travel on ice. They are valid if ice remains on arrival, or if they arrive within 2 days of collection below 10 °C. The lab stores them at 6 °C or below, unfrozen.
5. Analyse with blanks. Each extraction batch includes a reagent blank. Method 533 names PTFE products, solvent lines, methanol and aluminium foil as possible sources of background PFAS. It also keeps water samples away from glass, because PFAS can stick to it.
6. Report. Each compound gets a number, or a “less than” value at its reporting limit.

PFAS testing kits

A mail-in kit is only as good as the lab and method behind it. It should hold the method’s bottle and preservative, a field reagent blank and a way to ship cold, and the report should name the method, the compounds and a limit for each. The EPA’s PFOA and PFOS limits are 4.0 ng/L, and the EPA methods that reach that level all use LC-MS/MS in a lab.

PFAS testing requirements in the US, EU and UK

Where	Rule	Levels and duties
United States, public water systems	EPA drinking water rule, announced 10 April 2024	PFOA and PFOS 4.0 ng/L each; PFHxS, PFNA and HFPO-DA 10 ng/L each; a hazard index for mixtures. Initial monitoring by 2027
United States, update	Two EPA proposals, 18 May 2026	Would keep the PFOA and PFOS limits, with an option to request until 2031 to meet them, and rescind the limits for PFHxS, PFNA, HFPO-DA and the mixture index
European Union	Recast Drinking Water Directive, applying since 12 January 2026	“PFAS Total” 0.5 µg/L or “Sum of PFAS” 0.1 µg/L; each Member State uses one or both
England and Wales	Drinking Water Inspectorate guidance	Tier 1 below 0.01 µg/L, tier 2 below 0.1 µg/L, tier 3 at 0.1 µg/L or above, per PFAS and for a sum of 48 named PFAS

For scale, 0.1 µg/L is 100 ng/L. The Commission issued technical guidelines on methods for the two EU parameters in 2024. In its 2024 report for England, the inspectorate states that companies ran over 770,000 analyses for individual PFAS, and that 96% of samples were below the detection limit of their method.

These rules cover drinking water. For products, see PFAS in supplements and peptides.

PFAS testing for supplements, peptides and packaging

Supplements are closer to food than to water. The FDA’s method C-010.03 measures 30 PFAS and was validated in one lab across nine food and feed matrices. Its limits show how much the matrix matters: the limit of quantification for PFOA ran from 24 ng/kg in bread to 177 ng/kg in clams. The FDA says it has tested over 1,900 food samples on the US market.

Sample size matters too. The FDA method starts from 5 g of food; a 10 mg peptide vial holds one five-hundredth of that. With less sample, the same instrument gives a higher limit per gram, so a peptide test pools vials from one batch or accepts a higher reporting limit.

Peptides are often supplied as TFA salts. In a 2025 study, TFA made up 21.9 to 35.2% of the weight of seven peptide salts, by formula. TFA carries a CF3 group, so it meets the OECD definition of a PFAS (AGES). For testing, that means:

• Targeted panels do not report it. None of Methods 533, 537.1, 1633A or C-010.03 lists TFA; their shortest acids, such as PFBA, have four carbons. A clean panel says nothing about TFA.
• Fluorine screens may count it. On a TFA salt, an organic fluorine result can include the counter-ion along with any other PFAS, depending on how the fluorine is extracted.

In a peptide, TFA is measured as a counter-ion, as a share of the powder. Our guide to TFA in peptides explains the methods.

Containers matter as well. PTFE is a known source of background PFAS in the lab, which is why the EPA methods control caps, tubing and blanks. For what vials, stoppers and pens can release into a product, see extractables and leachables testing.

How to read a PFAS test report

What the report should state	Why it matters
Method, version and any changes	Method 533 allows other columns and instrument settings, but no changes to preservation, extraction or quality control
The compound list	“Not detected” and any sum cover only the listed compounds
A reporting limit for each compound, with units	Limits change with the matrix and the amount of sample
Blanks and how they were used	Method 533 forbids subtracting blanks and voids positive results if the blank reaches a third of the reporting limit. FDA’s food method allows subtraction when background cannot be avoided
Recovery of the labelled standards	Method 533 requires 50–200% for each labelled analogue
Raw data	Chromatograms per compound and transition show the peaks and any interference

Two labs can report different numbers for one sample if their lists, limits or blank rules differ, as with peptide results (why labs disagree).

How to choose a PFAS testing lab

For US drinking water, the EPA advises a state-certified laboratory using EPA-developed methods. Your state agency keeps the list, and the National Environmental Laboratory Accreditation Management System website can also help. For UCMR 5, only labs that passed the EPA’s Laboratory Approval Program, including proficiency testing, could analyse samples.

For soil, food or products, ask for the lab’s accreditation scope. A scope lists each method and sample type, so a lab accredited for PFAS in water may not be for powders. Before you order, ask:

• Which method and version, and is it modified?
• Which compounds, and what reporting limit for each in my sample?
• Isotope dilution, recoveries and blanks: which are reported, and are blanks subtracted?
• Will the report include chromatograms, and what is the turnaround from receipt?

What drives PFAS testing cost

• Method and compound list. Every added compound needs reference standards and calibration. Eighteen compounds in drinking water is a smaller job than 40 in soil.
• Sample type. Water is extracted by SPE directly. Under Method 1633A, soil is extracted into basic methanol, then cleaned up with carbon and SPE; fish tissue needs an extra extraction first.
• Reporting limits. Method 533 notes that some reporting limits are set by background contamination, so lower limits need cleaner blanks and more control.
• Add-ons. A TOP assay runs the targeted method twice. AOF or TOF needs a CIC instrument, high-resolution confirmation a second mass spectrometer, and non-target screening expert time.
• Quality control, timing and purpose. Field blanks, duplicates and rush turnaround add work, and a result for a regulator needs a certified lab and the named method.

Savings that hold: test the compounds the rule or your question names, and test one batch once. False savings: a screen that cannot name compounds when you need names, a report without reporting limits, or results with no blanks.

What HK Analytical does

We do not test for PFAS today. HK Analytical is adding microplastic, PFAS and BPA testing. Write to contact@hkanalytical.com to hear when it starts. You can also use the contact form.

For peptides, our counter-ion test already reports the share of the powder that is TFA or acetate. It is a composition test, not a PFAS panel. Our other tests include identity (LC-MS), purity (HPLC), content per vial and endotoxin, in any mix per sample. Results within days of receipt. Sterility (USP <71>, 14 days) is the one test that takes 14 days, because the method incubates for 14 days. Every number comes with its raw data, in a signed record you can check on /verify; the example report shows the format. We do not hold ISO/IEC 17025 accreditation. To price a panel, request a quote.