Total Oxidizable Precursors (TOP) - Eurofins introduces soil analysis

In the risk assessment of PFAS contamination in both soil and water, it is often justified to include so-called precursors. This since precursors can form PFCA (perfluorinated carboxylic acids) and PFSA (perflourinated sulfonic acids) upon degradation in nature, and thereby be relevant for future distribution and exposure. Since there are thousands of different PFAS substances, the precursors make up a very broad group of both known and unknown compounds. Among the more known, e.g. PFOSA and EtFOSE can be mentioned which form PFOS (so called PreFOS), and fluorotelomers, such as 6:2 and 8:2 FTS (fluorotelomer sulfonates), which yield different PFCAs. Moreover, there exists precursors that are not included in regular analysis, for example FTAB and FTSAS that can be found in firefighting foam, as well as substances that can not be determined.

In addition, precursors can be oxidized chemically to the corresponding perflourinated substances, typically PFCAs, and this is what takes place during TOP analysis. The conditions are chosen so that PFCA and PFSA, which were initially present, should not be affected. Eurofins in Lidköping has offered TOP analysis of water samples since last year. We are now extending and introducing TOP on soil samples as well as sediments. Several packages that match our usual PFAS "non-oxidized" range are available; SLV 11 (Swe Food Agency 11 PFAS, PLWY9), PFAS 22-pack (PLWNM) and PFAS 30-pack (PLWRI). It is possible to analyse TOP without performing a "regular" PFAS analysis at the same time. However, our recommendation is to order both analyses so that known and unknown precursors can be evaluated more fully. The reporting limit (LOQ) is for most substances 2-10 μg/kg DM. LOQ increases may occur if the sample dry matter content is <50%. For sampling we prefer that you use PE containers supplied by Eurofins and the recommended sample weight is 100g. The delivery time (TAT) is 10 working days.

More information about our TOP analysis in water.

More background on the TOP analysis and precursors (eg properties, concentrations, biodegradation and adsorption) can be found in our short-facts mini review.

More information on PFAS analyses can be found in our search engine.

Contact Eurofins experts!

Questions on PFAS and TOP 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