PFAS analysis in water, soil, food and other materials is more important now, more than ever. The number of PFAS compounds continues to grow, some estimates are up to 9000. PFAS is also being found in all areas of the environment sometimes in higher concentrations than expected.
Some of these persistent compounds are easier to analyze than others and it is very dependent on the matrix. Sample preparation is often the most difficult part of a workflow. While water, especially drinking water, is fairly straight-forward, others like soil may not be so easy to extract your compounds of interest.
The next consideration you need to make is are you looking for a set list of PFAS or do you want to discover and identify other PFAS in a particular sample. The optimal analytical instruments and strategies differ depending on the goals of your analysis. For targeted analysis many time sensitivity is a primary concern so you can achieve required detection limits. The most common PFAS of interest are PFOA and PFOS and many stares have set limits for these two compounds. While the current federal advisory limit, as of July 2021, is 70 part per trillion (ppt). Many states have set regulations for PFOA and PFOS at or below these limits. The state of California has just announced a goal of 1 ppt for PFOS and 7 parts per quadrillion (ppq) for PFOA. Sensitivity is certainly a primary concern for a workflow like this one.
On the other hand, if unknown screening is your goal, you will want to be able confidently identify as many compounds as possible. You may even want to go back and retrospectively interrogate data sets to see if newly discovered compounds were present in past samples. While sensitivity is always important in any analysis, resolution between compounds may take precedence in this analysis.
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