What is PFAS?

Per- and polyfluoroalkyl substances (PFASs) are a large class of chemically very stable organofluorine compounds with advantages such as water repellency, stain resistance and good insulation. They are particularly widely used in industrial manufacturing sectors such as food packaging, electronics, leather and clothing, construction and household products, and firefighting and medical supplies.

However, PFAS are persistent and mobile, are difficult to degrade in the environment and are therefore also called "forever chemicals", posing a serious threat to human health and the ecological environment.

Countries and regions around the world are progressively joining the camp that restricts and phases out PFAS.

On 7 February 2023, the European Chemicals Agency (ECHA) published a draft REACH restriction on PFASs affecting more than 10,000 substances. If adopted, it could become one of the largest chemical bans in European history.

Many US states, for example California with AB 1817, require that PFAS not be intentionally used and assess total organic fluorine content. Other countries have also successively established their own PFAS control measures.

Characteristics of PFAS

Persistence: extremely difficult to break down into harmless substances in the natural environment.

Mobility: the compounds migrate easily and may cause global pollution.

Bioaccumulation: they accumulate continuously in the food chain.

Biological toxicity: basically all PFAS compounds pose a hazard to living organisms and the environment, and more compound types still need to be analysed.

Regulatory requirements

Test methods

01 Ion chromatography (IC)

The sample is heated in a combustion furnace so that the target substances are converted into fluoride ions, and the total fluorine or extractable organic fluorine content of the solution is measured with an ion chromatograph.

02 Liquid chromatography - tandem mass spectrometry (LC-MS/MS)

After sample preparation, the substances are separated with a liquid chromatograph and analysed qualitatively and quantitatively with tandem mass spectrometry.

03 Gas chromatography-mass spectrometry (GC-MS)

After suitable pre-treatment, the substances are separated with a gas chromatograph and analysed qualitatively and quantitatively by mass spectrometry.

Advantages and drawbacks of the test methods

Method 1 above measures total fluorine content and is a screening method. The PFAS recently reported in foreign food packaging were basically tested using total fluorine methods. The advantage of such methods is that the total fluorine can be obtained relatively quickly, but they cannot exclude interference from fluorine-containing substances that are not PFAS, nor can they identify or quantify which PFAS are present.

Methods 2 and 3 above enable accurate qualitative and quantitative analysis of target substances, but they place high demands on equipment and personnel and the range of compounds that can be tested is limited. Quantification requires the corresponding reference standards.