Figure: Molecular structure of PFOS and PFOA


ALS offering for PFAS testing



Sample volume

Soil (23 compounds)

0,025 – 0,3 µg/kg

5 g

Sediment (23 compounds)

0,025 – 0,3 µg/kg

5 g

Water (35 compounds)

0,0012 – 0,01 µg/L

0.25 L


A multitude of poly- and perfluoroalkyl substances (PFAS), have been used for decades for diverse applications such as water repellent “outdoor” fabrics, stain resistant carpets, non-stick frying pans and firefighting foams.

PFOS (perfluorooctane sulphonate) and PFOA (perfluorooctanoic acid) are likely the best known examples of PFAS and most frequently found in the environment.

However, there are several thousand varieties of PFAS. A standard analytical suite normally contains between 20 and 35 compounds and is insufficient for risk assessment purposes.

In order to quantify the total PFAS concentration in a sample a so-called TOP Assay has been developed. A top assay is a pre-treatment step whereby all PFAS in a sample goes through a process where they chemically are oxidised into “identifiable” compounds e.g PFOS. 



PFOA has been produced commercially since the 1940’s with one of the main applications being in Teflon.

Around the turn of the millennium there was enough evidence around the negative effects of PFOA for the USEPA to order companies producing PFAS to investigate the effects on humans and the environment.

Following the investigation one major producer in 2000 decided to outphase the production of PFOA while another 8 agreed to gradually stop production and outphase the compound by 2015


PFOA has a number of negative healt effects including being carcinogenic and an immune system toxicant. EFSA's 2208 Tolerable Daily Intake for PFOA is 1.5 µg/body weight or 120 µg per day for a person weighing 80 kg. 



Similar to PFOA, PFOS was commercially produced since the 1940’s and has been gradually outphased by the main international producers.

In 2006 the EU placed a limit of 0.005 % of PFOS in finished and semi-finished products with excemptions for certain industrial applications. This was later included in REACH and in 2010 the limit was lowered to 0.001 %.

PFOS was added to the list of POP’s under the Stoclholm convention in 2009.


PFOS is classed as toxic with a moderate acute toxicity. The compound is carcinogenic and an endocrine disruptor in addition to having a number of other negative effects on health.

EFSA's 2208 Tolerable Daily Intake for PFOS is 0.15 µg/body weight or 12 µg per day for a person weighing 80 kg.

Table: International threshold values for PFAS





Sediment (PFOS)

0.17-3100 µg/kg-1


Water (PFOS)

25-360 µg/l-1

  1. 2229/2007 Norwegian Pollution Control Agency. Limit depending on classification

For 0.5 L of sample