Not all fluorine is PFAS: Why the distinction matters more than ever
When Swedish TV came to examine PFAS in frying pans, the key question wasn’t just whether fluorine was present but what kind. During the filming, we interviewed Lisa Skedung to understand how our method can distinguish PFAS from inorganic fluorine, and why that difference matters as regulations tighten.
What are PFAS?
PFAS are a large group of synthetic chemicals characterized by extremely strong carbon–fluorine bonds, which make them highly stable. These organic fluorinated compounds have been used for decades to give materials water-, grease-, and dirt-repellent properties. They have been used in products such as ski wax, baking molds, food packaging, non-stick frying pans, and textiles.
Their chemical stability means they break down very slowly in nature, which has earned them the nickname “forever chemicals.” They spread easily in the environment and are now found in both humans and animals worldwide.
What other sources of fluorine exist?
Fluorine can also originate from naturally occurring inorganic fluorides in soil, minerals, bedrock, and water.
Inorganic fluorine (fluoride) can be present in materials containing fluoride salts, glass fiber, or mineral fillers. These sources can contribute to total fluorine levels above 50 ppm without involving PFAS at all.
This is why total fluorine measurement alone is not sufficient to confirm PFAS presence.
How can pyrolysis-GC/MS distinguish inorganic fluorine from PFAS?
Pyrolysis-GC/MS works by rapidly heating a material so that it breaks down into very small organic fragments, which are then analyzed in the instrument.
Because PFAS are organic fluorinated compounds — meaning they contain both carbon and fluorine — they form characteristic fragments when broken down at high temperature. These fragments can be detected and linked to PFAS structures.
Inorganic fluorine behaves completely differently. It contains no carbon and does not vaporize in the same way. Therefore, it does not form organic fragments that can be separated in the gas chromatography (GC) step or detected in the mass spectrometry (MS) step. As a result, inorganic fluorine does not appear in a pyrolysis-GC/MS analysis.
If a sample shows high total fluorine but no PFAS fragments in pyrolysis-GC/MS, this indicates that the fluorine likely originates from an inorganic source such as minerals, glass fiber, or fluoride salts.
The method therefore makes it possible to determine whether fluorine in a material comes from PFAS or from inorganic fluorine — a distinction that is not commonly addressed in routine testing.
What are the advantages of pyrolysis-GC/MS?
- Can determine whether fluorine originates from PFAS or not
- Can detect and distinguish different polymeric PFAS
- Provides rapid and relatively cost-effective screening
- Works on all types of materials, including paper, plastics, and textiles
- Supports regulatory enforcement by flagging suspected PFAS use
- Serves as an important complement to total fluorine measurement, which alone cannot distinguish PFAS from other fluorine sources
What does pyrolysis look like in practice?
The pyrolysis process takes place in a closed system, so there is little visible activity. What the user sees are the results — characteristic peaks in a graph. These peaks represent the chemical fragments formed when the material is heated.
A very small sample is placed on a pyrolysis foil, often covered with platinum, and inserted into the pyrolysis chamber. The sample is heated through an electrical impulse conducted via the platinum foil. During this rapid heating, the material breaks down into smaller fragments, which vaporize and are transferred into the GC-MS instrument. There, they are separated in the gas chromatograph and identified in the mass spectrometer.
How can this method support stricter PFAS regulation?
We have developed a systematic workflow for PFAS testing that has been referenced in background documentation to the proposed class-wide PFAS restriction under REACH.
The workflow is structured as follows:
- Start with total fluorine analysis
- If levels exceed 50 ppm, proceed with pyrolysis-GC/MS to determine whether the fluorine originates from PFAS or from inorganic sources
- Only proceed to targeted analysis of specific PFAS substances if necessary
This stepwise approach helps avoid false positives — situations where total fluorine is high but no PFAS are present.
If both total fluorine and pyrolysis-GC/MS confirm PFAS, there is often no need to proceed with more expensive and time-consuming targeted analyses, especially since such methods frequently do not capture polymeric PFAS used for functionality.
For companies requiring rapid screening, analysis can also begin directly with pyrolysis-GC/MS. If PFAS fragments are detected, this effectively indicates total fluorine levels at or above 50 ppm.
The method will also play a role in OEKO-TEX certification, where pyrolysis-GC/MS can be used to demonstrate that a material does not contain PFAS and may therefore qualify for exemption from the 50 ppm total fluorine threshold, provided hydrolysis results remain within their concentration limits.
In summary
This method enables broad screening for PFAS, including polymeric PFAS, while also allowing follow-up of samples with total fluorine levels above 50 ppm to determine whether the fluorine originates from PFAS or from inorganic sources.
As regulatory requirements tighten, that distinction becomes critical.
Testing for PFAS is increasingly common. The ability to differentiate inorganic fluorine from PFAS using pyrolysis-GC/MS is far less so — and that is precisely where the analytical advantage lies.