PFAS on Our Plate: Why Food Testing Needs Stronger Standards

Published 14 May 2026 · By Dr Helena Marsh, Senior Scientist, Food and Beverage Reference Materials

For most of the last decade, PFAS in food was a monitoring question. Authorities gathered occurrence data, laboratories reported what they found, and the results informed dietary exposure models. That phase has ended. Maximum levels for perfluoroalkyl substances in specific foodstuffs are now enforceable, and a result above a limit has commercial and legal consequences for a producer. The analytical community has inherited a regulatory obligation that its reference material infrastructure was never designed to support.

What changed, and why it is hard

Maximum levels apply to PFOS, PFOA, PFNA and PFHxS individually and as a sum, across fish, crustaceans, molluscs, meat, offal and eggs. The limits sit in the low micrograms per kilogram range, and for some commodities well below one microgram per kilogram. Testing at those concentrations in a fatty, protein-rich, highly variable matrix is a genuinely difficult measurement, and it is not the same problem as testing drinking water.

• Matrix complexity: lipids, phospholipids and bile acids co-extract and suppress ionisation, and several endogenous compounds produce transitions that interfere with PFOS confirmation.
• Branched and linear isomers: technical PFOS contains both, environmental exposure delivers both, and quantifying against a linear-only standard systematically under-reports.
• Low limits of quantification: validating reliably below the maximum level leaves little analytical headroom for recovery variation.
• Background contamination: laboratory air, solvents, consumables and even sample packaging can contribute at the concentrations now being reported.

The reference material gap

Water and soil analysts have a reasonable choice of characterised materials. Food analysts have far less. Many laboratories validate using spiked blank matrix prepared in house, which demonstrates precision and recovery of the spike but says nothing about whether the method releases natively incurred PFAS bound within tissue. Incurred residues behave differently from freshly added ones: they partition into protein-bound fractions that a gentle extraction may simply not reach.

That distinction matters when two laboratories disagree about a borderline result. A matrix certified reference material with a naturally incurred contamination profile is the only way to demonstrate trueness rather than merely repeatability. Where such materials do not yet exist for a commodity, the practical alternatives are a well-characterised in-house material value-assigned through a proficiency testing round, or participation in interlaboratory comparisons that generate consensus values for real samples.

Building a defensible food PFAS method

Laboratories that have passed assessment on this analysis tend to have addressed the same set of points:

1. Use isotopically labelled internal standards, preferably 13C-labelled, for every quantified analyte rather than a single surrogate for the class.
2. Calibrate with standards that reflect the isomer profile you expect to encounter, and state the basis of your reported value.
3. Report on an anion basis, and document the conversion factor applied to any salt-form standard.
4. Control background rigorously: fluoropolymer-free flow paths, a delay column, dedicated consumables and blanks at every stage.
5. Validate at and below the maximum level, not at a convenient mid-range concentration.
6. Verify trueness with a certified or consensus-valued matrix material at least annually.

Beyond the four regulated substances

The regulated list is a starting point rather than an endpoint. Occurrence studies consistently detect ultra-short-chain species such as TFA and PFBA, fluorotelomer precursors that degrade to regulated acids, and emerging replacement chemistries including GenX and ADONA. Several of these are poorly retained on standard reversed-phase chemistry and are missed entirely by methods optimised for the long-chain acids. Laboratories planning capital investment should assume the analyte list will grow, and choose chromatography and standards that can accommodate it.

Why this is worth the effort

Dietary intake is the dominant route of human PFAS exposure for most of the population. The measurements made in food testing laboratories feed directly into exposure assessments, enforcement decisions and, ultimately, the levels that people carry in their blood. Weak comparability between laboratories does not just create commercial disputes; it degrades the evidence base that regulation depends on.

Stronger standards — in both senses of the word — are how the sector fixes that. Matrix-matched certified reference materials, isotopically labelled internal standards with documented isotopic purity, and proficiency testing that uses real incurred samples are unglamorous infrastructure. They are also the difference between a number and a result that can be trusted.