How Food Safety Laboratories Detect PFAS: What the Detection Limit on Your Report Actually Means

A “non-detect” result on a PFAS report does not mean your product contains zero PFAS. It means your food safety laboratory didn’t find PFAS above a defined reporting threshold — and that threshold, along with the method used to establish it, is where most brand managers stop reading when they really shouldn’t.

PFAS (per- and polyfluoroalkyl substances) are a family of more than 12,000 synthetic compounds, with contamination routes that span agricultural soil, food contact materials, fluorinated cosmetic raw materials, and botanical supply chains. The regulatory picture shifted considerably in 2024 and 2025 — EPA issued its first-ever drinking water MCLs for specific PFAS compounds, and California’s AB 2771 cosmetic ban took effect in January 2025. The analytical methods available to commercial food safety laboratories vary more than most brand managers realize.

Getting a clean PFAS report matters. Understanding what your lab was actually testing for — and how sensitive that testing was — is a different, more important question.

Three Methods, Three Very Different Stories

Most food safety laboratories running PFAS analysis anchor their work to one of three EPA methods: Method 533, Method 537.1, or Method 8327. All three use liquid chromatography tandem mass spectrometry (LC-MS/MS). All three are credible, peer-reviewed, and routinely accepted by regulators. And they differ meaningfully in which compounds they target and which sample matrices they were designed for.

EPA Method 537.1 is the established drinking water standard — 40 PFAS compounds, with reporting limits typically below 1 ng/L for most analytes in aqueous samples. It’s highly sensitive and well-validated for water. Applied to food matrices, it requires extraction and cleanup steps, and lab performance on those additional steps varies considerably. Before accepting a 537.1-based food result, ask for the matrix spike recovery data. Recovery percentages between 70% and 130% are acceptable for most PFAS analytes; anything outside that range suggests matrix interference that the result may not be correcting for.

EPA Method 533 was designed specifically to capture shorter-chain PFAS — the compounds the fluorochemical industry shifted toward after longer-chain PFOA and PFOS faced international regulatory pressure beginning in the early 2000s. Method 533 covers 25 compounds including PFBS, PFBA, and HFPO-DA (commonly known as GenX), most of which don’t appear on the 537.1 target list at all. If your formulation involves fluorinated surfactants, fluorinated processing aids, or food packaging with fluorinated coatings, Method 533 is the panel more likely to find what you need to know. The catch: many brands run 537.1 because it’s the more commonly offered method, and come away thinking their shorter-chain exposure profile is clean when they’ve simply never tested for it.

EPA Method 8327 was purpose-built for non-aqueous matrices — soils, sludge, and solid food samples. It covers 24 PFAS, uses isotope dilution for quantitative accuracy, and achieves reporting limits typically in the range of 0.5 to 2 µg/kg in food matrices, depending on the analyte and sample type. For finished supplement capsules, botanical ingredient powders, or solid cosmetic formats, Method 8327 is usually the most appropriate starting point.

Beyond those three, some food safety laboratories now offer the Total Oxidizable Precursor (TOP) assay for clients who want a fuller picture. The TOP assay oxidizes PFAS precursor compounds — fluorinated molecules that aren’t themselves PFOA or PFOS but can convert to them over time in biological systems — and measures the resulting products. It captures PFAS burden that every targeted-compound method misses entirely. It’s not a regulatory requirement anywhere yet. But for brands conducting thorough due-diligence screening on high-risk ingredient categories, it’s a meaningful addition to a standard targeted panel.

Why “Non-Detect” Is Only as Meaningful as the Number Next to It

Here’s a scenario that plays out regularly in product compliance work. A brand submits a finished product sample to a food safety testing laboratory, gets back a report showing “ND” (non-detect) or ”< RL” across the entire PFAS panel, and treats it as a clean bill of health for regulatory and retailer purposes. What they don’t notice — or don’t know to look for — is the reporting limit column.

A lab running a PFAS screen with a reporting limit of 10 µg/kg will mark a sample “non-detect” that another lab, using a method with a 0.5 µg/kg reporting limit, might detect at 3 µg/kg. Both reports are technically accurate. Only one of them is useful in the current regulatory climate.

EPA’s April 2024 final PFAS maximum contaminant levels for drinking water placed PFOA and PFOS at 4 parts per trillion — the most stringent standards EPA has ever issued for any contaminant in water. PFNA, PFHxS, and HFPO-DA are each regulated at 10 ppt. These numbers don’t directly govern food or cosmetics today. But they establish the regulatory direction of travel, and FDA’s food safety program has signaled clearly that food-relevant PFAS standards are on the horizon. Brands that calibrate their testing programs to where regulations are heading — rather than where they currently sit — are the ones that avoid expensive reformulation and crisis recalls later.

California, as is often the case, is already further down that road. AB 2771, effective January 1, 2025, bans intentionally added PFAS in cosmetic products sold in the state. California represents roughly 12% of US retail consumer product revenue, which makes it a de facto national standard for most cosmetic brands. “Intentionally added” is narrower than “detectable at any level,” but credible compliance still requires a food safety laboratory running at sufficient sensitivity to detect trace-level contamination from fluorinated raw material impurities. A cosmetic PFAS panel with a 5 µg/kg reporting limit doesn’t give you a defensible answer in that context.

How to Read a PFAS Report Without Being Misled by It

A few specific things to check on any PFAS test report before filing it as evidence of compliance:

Method citation. The report should name a specific EPA method or an equivalent validated reference method. “In-house method” without supporting validation documentation is a flag worth following up on — ask for the method validation summary, including precision, accuracy, and detection limits.

Analyte count. A 12-compound panel and a 40-compound panel are both described as “PFAS tests.” They aren’t equivalent. Review which specific compounds were included, and confirm the list covers the shorter-chain compounds relevant to your ingredient and packaging chemistry.

Reporting limits. For finished food and cosmetic products in 2026, reporting limits at or below 1 µg/kg give you meaningful analytical sensitivity. For liquid formulations or water-soluble ingredients, sub-ng/L sensitivity is more appropriate.

Internal standards. Accurate PFAS quantitation requires isotope-labeled internal standards — ¹³C-labeled PFAS analogs added at the very start of sample extraction to correct for losses during sample preparation. A competent food safety laboratory will list the internal standards used in the method section of the report. If they’re not listed, ask.

Matrix spike recovery. For any non-aqueous matrix, ask for the matrix spike recovery data if it isn’t already on the report. Recoveries outside the 70–130% window should prompt a conversation about method applicability to your specific sample type.

Building a PFAS Testing Program That Actually Protects You

Good PFAS testing program design starts with a short supply chain inventory: where are the fluorinated chemistries in your process? That includes PTFE in manufacturing equipment, fluorinated release agents, fluorinated coatings on packaging, and any fluorinated ingredient in the formulation itself. That inventory determines the right analytical method.

If the risk is primarily longer-chain compounds from agricultural contamination in botanical ingredients, a 40-compound LC-MS/MS panel adapted for your matrix is the right tool. If the risk involves fluorinated surfactants or shorter-chain compounds from cosmetic raw materials, Method 533 or a combination approach is more appropriate. If you’re establishing a baseline on a new product line and the contamination pathway isn’t clear yet, a TOP assay alongside a targeted panel is how you get a defensible starting picture.

At Qalitex, when a food brand, supplement company, or cosmetic manufacturer comes to us with PFAS questions, the first conversation is always about which regulatory or commercial standard they need to satisfy. That shapes every subsequent decision — compound list, method selection, reporting limit targets, and how the result is framed for your compliance documentation. We’re not running one-size-fits-all panels and sending you reports to file. We’re helping you understand what the data means.

The PFAS regulatory environment will tighten further over the next two to three years. What constitutes adequate due diligence today may well be insufficient by 2028. The brands getting ahead of that curve are the ones that already understand their reports — and already know to ask the right questions of their laboratory before the regulators do.

---

Written by Nour Abochama, Vice President of Operations, Qalitex Laboratories. Learn more about our team

Talk to our team about your testing needs. Contact us

Related from our network

• FDA Regulatory Strategy for Chemical Compliance Programs — Aurora TIC provides 21 CFR and FDA audit preparation support for brands navigating emerging PFAS and chemical testing requirements.
• Raw Material Supplier PFAS Screening and COA Verification — Ayah Labs supports ingredient-level PFAS risk assessment and supplier qualification for food, supplement, and cosmetic brands.