As worldwide per- and polyfluoroalkyl substances (PFAS) contamination becomes ever more evident, expanding analytical capabilities has never been more important in PFAS testing. Currently, attention is primarily focused on drinking water and other source water contamination. Addressing the issues of PFAS in water is among the highest priorities for making our health and environment safer. However, PFAS is not found only in water, therefore, detection in other sources in the environment, is just as crucial.
One of the places PFAS is found other than water, is in soil as a result of run-off from sources such as areas where aqueous firefighting foams have been used, landfills and manufacturing sites. These compounds are problematic in soil because they can leach into groundwater or contaminate any vegetation growing in that soil.
Analyzing compounds in soil presents many more challenges as compared to simple matrices like water. Soil contains many more components, which could interfere in analytical methods. PFAS molecules are very persistent and can also be trapped within the soil, which makes extraction difficult. When using manual extraction methods, the solvent does not get into all the soil sample, and greatly decreases recoveries, even to unacceptable levels. One of the causes for poor recovery is the fact the soil tends to clump together preventing the solvent from accessing the entire sample.
While sonication and vortex can help, it still does not always give acceptable yields. During a recent collaboration between Pacific Rim Laboratories and Thermo Fisher Scientific, Pacific Rim observed quite unacceptable recovery levels for some of the PFAS molecules, ranging from 0 to 50%. All the extraction and analysis data generated by Pacific Rim Labs can be viewed by downloading the customer application note: Extraction and analysis of poly- and perfluoroalkyl substances (PFAS) from soil.
Using accelerated solvent extraction, using an instrument such as the Thermo Scientific™ Dionex™ ASE™ 350 Accelerated Solvent Extractor, solves many of the issues present in manual extraction methods. The Thermo Scientific™ Dionex™ ASE™ 350 Accelerated Solvent Extractor uses high temperatures to ensure just about complete solvent distribution throughout the soil sample to greatly increase recoveries for organic molecules, like PFAS, to improve results.
Thermo Scientific™ Dionex™ ASE™ 350 Accelerated Solvent Extractor, also uses high pressure because the temperatures used are above the solvents’ boiling point; high pressure keeps the solvent as a liquid and boosts extraction efficiency. Thermo Scientific™ Dionex™ ASE™ 350 Accelerated Solvent Extractor, is also automated which helps increase lab efficiency by allowing you to do other tasks in your lab. Less solvent is also required because the instrument is so efficient, which will save your lab on costs and make it more environmentally friendly.
Thermo Scientific™ Dionex™ ASE™ 350 Accelerated Solvent Extractor, excels at PFAS extraction from soil because of these benefits, which have been highlighted above. Leading environmental laboratories are using the ASE 350 for this type of work. Laboratories are noting that previous difficulties in recovering long-chain PFAS from soil using sonication/vortex methods were overcome by using ASE.
To learn more about PFAS testing, our start-to-finish PFAS analytical solutions, and free access to our PFAS Toolkit, visit our dedicated PFAS web pages.