Overlooked PFAS compound in water

Per- and polyfluorinated alkyl substances (PFAS) are a wide group of compounds. When it comes to water, both surface and drinking water, regulation typically covers common sulphonic acids (PFSA; e.g. PFOS) and carboxylic acids (PFCA; e.g. PFOA). In some cases, as in the Swe Food Agency’s PFAS11 other substances such as 6:2 FTS might be included. So called novel PFAS is a range of PFAS that are either replacement products (e.g. GenX) or “older ones” that have not previously been (fully) addressed.

FHxSA or alternatively PFHxSA (fluorohexanesulphone amide) is a PFAS that has been shown to be present in some older firefighting foams (AFFF) alongside with PFOS, PFHxS and larger molecules with an FHxSA moiety. FHxSA is a shorter (C=6) homologue to FOSA (or PFOSA), and although less is known it is likely that it in natural systems is degraded to PFHxS in the same manner as FOSA to PFOS.

A major drinking water contamination was discovered in Kallinge, Ronneby in Sweden 2013. The PFAS was thought to originate from the airfield in the vicinity of the Brantafors waterworks. Eurofins has sampled the water in the stream Klintabäcken close to the extraction wells G6 and G7. FHxSA was found to be the third largest PFAS substance present (~105 ng/l; sampled at high flow in the stream) with similar concentrations at the two sites. PFOS and PFHxS were still dominant, but the level of FHxSA was for example higher than PFOA and PFHxA.

In a sample from another Swedish city with raw water contaminated by PFAS, FHxSA was also identified but at a much lower concentration (1.3 ng/l). Here PFHxS was the major PFAS found, but an additional observation was the presence of the shorter amide homologue FBSA (6 ng/l; C=4).

Moreover, in research work on AFFF polluted soils, performed in collaboration with Örebro university and NIRAS, FHxSA has been shown to be present in soil as well as leachates. This was seen especially for soils at the same time high in PFHxS and PFOS. We have also determined FHxSA in fish and mussels though it should be stressed that the number of samples has been limited so far.

Although our studies so far have been very limited they point to a potentially significant contribution of FHxSA in some cases, and that the compound might deserve attention in the context of drinking water contamination. Further work is clearly needed to elucidate its importance.

Eurofins offers FHxSA in both clean (LW1V0; LOQ 0.3 ng/l) and unclean (LW1UI; LOQ 1 ng/l) water as part of our novel PFAS range. The substance can be added to our standard packages for PFAS 2, 11, 25 and 33. Please order the package code plus the one for FHxSA, no further volume/bottle is needed. See our online catalogue for more information.

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Questions on PFAS can be answered by Patrick van Hees: tel 010-490 8151, e-mail: patrickvanhees@eurofins.se

Overlooked PFAS compound in water

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