Analysis of novel PFAS in water - GenX, F-53B, (A)DONA and PFECHS

The widespread contamination as well as human and environmental exposure of PFAS has been paid much attention to in recent years. This is not at least the case for consumption of drinking water that may have been polluted e.g. from firefighting training sites. As the historically most used PFAS substances, especially PFOS and PFOA, have been banned and/or phased out, the fluorinated alternatives and replacement products are gradually put into focus as well.

The “classic” perfluorinated compounds, such as PFOS/PFOA, consist of a fully fluorinated alkyl chain with a functional group (e.g. sulphonate) at the end. The new PFAS can have other structures and, for example, be ether or cyclic molecules. Moreover, one of them (F53B) has a substituted chlorine atom. Not all replacement compounds are all new; some have existed alongside PFOS and PFOA for a number of years. These substances are currently not covered by any standard PFAS pack such as PFAS11 or similar. Eurofins can now offer a number of new PFAS, that have been most discussed and investigated, and are to some extent already being regarded as emerging contaminants.

GenX is perhaps the replacement compound that has drawn most attention. In fact GenX is the technology where 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)propanoate (FRD-902; HFPO-DA) is used  as a process agent in manufacturing of fluoropolymers e.g. PTFE (Teflon) instead of PFOA. Consequently HFPO-DA is commonly referred to as GenX. Recently (Nov 18) US-EPA came with the first draft toxicity assessment (draft oral reference doses; RfD) for the compound with values in the same order as PFOS. The worldwide occurrence of GenX in surface water was recently demonstrated in a paper by Pan et al (2018), including Lake Mälaren in Sweden (mean ~1.5 ng/l, similar to PFOA). Also the similar HFPO-TA was found in water, but at lower concentrations. Analysis of GenX, which is a PFAS ether, is a well-known challenge. Eurofins can now offer GenX in water as well as HFPO-TA at a low limit of detetction (LOQ; clean water 0.3 ng/l; unclean 1 ng/l). Though, a separate method is required and GenX (HFPO-DA) plus HFPO-TA can thus not be combined with any regular PFAS pack. Another replacement for PFOA is (A)DONA. Like GenX it is an ether that is used as processing aid during polymerization. Also this substance is now possible to analyse in water (LOQ 1 ng/l) and can added to our standard packs or be ordered on its own.

In the past PFOS has been used as wetting and mist suppressing agents in various types of metal plating. Over time PFOS has been replaced by other fluorinated compounds. One substitute that is now being monitored is the ether sulfonic acid 6:2 Cl-PFESA (F-53B) with one chlorine atom. In addition, the homologues 4:2 and 8:2 have been identified. Like PFOS, PFECHS (Perfluoro-4 ethylcyclohexane-sulfonate) is a perflourinated C8 sulphonate which major use is as an anticorrosive additive in aircraft hydraulic fluids, but other potential applications are possible too. In an upcoming Nordic council report this cyclic PFAS has been quantified in the Nordic environment in matrices ranging from surface water and WWTP effluent to biota (fish and marine mammals). PFECHS as well as 4:2, 6:2 (F-53B) and 8:2 Cl-PFESA are now offered in water with a LOQ of 1 ng/l. These can be analysed as add-ons to our regular PFAS packages or run as single compounds.

Besides the novel substances given above Eurofins also extends the portfolio with two other PFAS. Ultrashort PFAS are molecules with two or three carbon atoms and are attracting more attention. For example ultrashort PFAS has been identified in surface, ground and waste waters. Now there is a possibility to analyse one of these compounds PFPrS (Perfluoropropane sulfonic acid). PFHxSA (Perfluorohexane sulphonamide) is an analogue compound to PFOSA, and a precursor to PFHxS. It has been found in e.g. groundwater. Both these PFAS substances can be combined with present regular packages and have a LOQ of 1 ng/l too.

Overview of order numbers:

*Accredited

GenX and HFPO-TA require a separate method and can not be combined with other analytes or packages. Two 100ml PE bottles are required. The other compounds can be added to our present range of PFAS packages. If ordered separately 2x250ml is needed for clean waters and 2x100ml for unclean. Please use PE bottles supplied by Eurofins to avoid contamination. Additional details on PFAS analyses can be found in our search engine.

More information:

Pan et. al., Environ. Sci. Technol. 2018, 52, 7621−7629 (abstract free of charge)

Contact Eurofins experts!

Questions on PFAS can be answered by Patrick van Hees: tel 010-490 8151, e-mail: patrickvanhees@eurofins.se or Needa Shaheen: tel 010-490 8150, e-mail: needashaheen@eurofins.se