TOP and Linear/Branched isomers

In addition, TOP (total oxidizable precursors) can be determined. TOP is a method that can be used to chemically oxidize precursors to measurable PFCA such as PFHxA and PFOA. Precursors are compounds, known and/or unknown, that also in nature, can degrade to their perflourinated “backbones”. By measuring the increase in PFCA after oxidation it is possible to estimate the contribution of these “hidden” compounds. Literature values and our own studies show that the increase can be several hundred percent or even more. When it comes to soil polluted by firefighting foam (AFFF) the PFAS originally present may only correspond to a few percent. TOP can be applied to water, soil and firefighting foam. Contact us regarding other matrices.

Eurofins can also provide speciation of linear (lin) and (sum of) branched (br) forms of PFAS. Branched PFAS are associated with the so called ECF (electrochemical fluorination) which yields a mixture of linear and branched molecules. On the contrary the so called telomerization (FT) technique will result in linear forms only. Branched forms have slightly different physicochemical properties with regard to e.g. higher water solubility, lower adsorption to soil, lower bioaccumulation and possibly faster degradation of precursors. PFAS in foam have been produced using both methods and analytical determination of lin/br in soil and water may give insights into which type of AFFF that has been used. For soil and water there is a smaller pack with speciation for four major PFAS and a bigger pack  with nine substances (C4-C8). These packs can also be applied to TOP determinations