Linear and branched forms of PFAS - extended range in water, soil and TOP assay
The last 5-10 years isomeric forms of PFAS have been more and more discussed and the impacts assessed. There are small but significant differences in physico-chemical properties such as hydrophobicity and water solubility between branched and linear forms which lead to changes in biochemical reactions and transformation, bioaccumulation and thus toxic exposure. Adsorption to solids is another property affected. As a whole these factors will have an effect of the relative distribution in environmental matrices such as soil, water as well as biota.
Besides the ”regular” PFAS typically measured there are frequently precursors, both known and unknown, present in environmental samples. TOP (total oxidizable precursors) is a method in which these precursors are chemically oxidized to corresponding perfluorinated carboxylic acids (PFCA). The study of branched and linear forms of the resulting PFCAs has been put forward as one way of shedding light on the origin of the precursors in combination with the PFCA composition (e.g. ECF sulfonamides vs telomers).
Eurofins introduced already 1.5 years ago analysis of the sum of branched isomers and the linear (n-) form of PFOS, PFOA, PFHxS and PFOSA in water, which was later on offered for soil samples too. Now we introduce an exented range of branched (sums) and linear forms of PFCAs (C5-C8) and PFSA (C4, C6-C8; perfluorosulphonic acids) plus PFOSA. Packages are available for both water and soil. Moreover, we can now also determine branched/linear isomers in the TOP assay and thus give further assistance in the evaluation of the oxidized precursors.
There are four new packages: for water LW187 (PFAS) and LW188 (TOP), and for soil LW1BX (PFAS) and LW1CX (TOP). These packs can be ordered together with our regular PFAS and TOP packages (e.g. PLWFK), and branched/linear concentrations reported will correspond to the PFAS compounds included in the particular package. Limits of quantification (LOQ) for branched/linear forms are the same as for total PFAS/TOP concentrations and the sample amount/volume and delivery time are not changed.
In addition, we would like to inform that we have now lowered the LOQ for PFHxS in our PFAS packages PLW6I, PLWFK and PLWAF to 0.2 ng/l.
More information on isomeric forms and their properties can be found in our updated ”short facts” review.
Contact Eurofins experts for more information
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