PFAS Analysis Puzzle: The Potential of Non-Targeted Analysis

For those spending time focused on matters related to per- and polyfluoroalkyl substances (PFAS), several specific types of properties often are synonymous with PFAS impact including metal plating facilities, DoD installations, airports and fire training facilities. However, other property groups appear to be increasingly concerned about their potential PFAS risk. A challenge for these facilities is determining how best to go about evaluating the real, or even perceived, risk. What about large properties for which estimating the extent of impact or contamination is highly uncertain? The group of laboratory analytical methods that are used to quantify PFAS compounds, while improving in breadth of PFAS-related compounds detectable (consider the thousands of related constituents that fall within the PFAS library) and accuracy of determination, only add additional complications to this already difficult task.

PFAS analytical method limits

Several limitations currently exist with targeted PFAS analytical methods. The accounting of these limitations is, however, by no means a criticism of any laboratory – commercial or research – involved with providing such analytical services. Rather, we note that, even with the exceptional work by the laboratory community and rapid development of new methods, the science of analytical chemistry, and development of regulatory-defensible protocol (which must undergo rigorous quality assurance and reproducibility schemes) cannot keep up with the pace of compound cataloguing leading to, as Naidu, et al (2020)[1] exclaimed, “a lack of harmonized analysis protocol for the wide range of PFAS occurring in environmental samples.” Specific limitations include, but are not limited to:

1. An estimated 10,000 unique PFAS compounds have been identified to be present in the environment with the list continuing to grow. However, existing analytical methods account for only 30 to 75[2] PFAS compounds.
2. Running as high as $300 to 400 per sample, the economics of PFAS analysis, particularly on a large project where hundreds to thousands of sample analyses may be necessary, can be expensive.
3. While the list of commercial laboratories with capabilities to conduct PFAS analysis is growing, few laboratories have been certified by regulatory agencies, and even fewer have the capacity to run high volumes of samples. As the need for PFAS sampling and analysis increases nation-wide, laboratory turnaround time could become a significant bottleneck.

Non-targeted analysis methods

To address these concerns, non-targeted analysis to determine the presence of a “chemical class,” as opposed to specific compound analysis, is sometimes floated as a possible solution to initial evaluation of compound occurrence. As an analog, consider how our practice historically applied the analysis of total petroleum hydrocarbons (TPH) to evaluate the presence of related compounds. This made sense with typical fuel compositions consisting of hundreds of unique constituents. In a similar way, a non-targeted analysis of PFAS may be a first line screening technique that could be both quick and cost effective. The development of these analysis for this exact purpose was even suggested within Minnesota’s newly released PFAS Blueprint.

However, existing non-targeted analysis methods, such as the total oxidizable precursor assay (TOP) or high-resolution mass spectrometry techniques like quadrupole time-of-flight (qTOF) are just as expensive per sample as traditional methods and are prone to bias.[3] Essentially, you might be paying the same price for data of a lesser quality. The concept of a “PFAS screening tool” approach still is worth evaluating as evidenced by the pursuit of the United States Environmental Protection Agency (USEPA), which is in the process of developing a new analytical method for measuring total organic fluorine (TOF) in environmental samples to compare to background organo-fluorine levels. In theory, with the right sensitivity and accuracy, these types of analyses could be game changers if the price is right. The USEPA TOF method is anticipated to be published in 2021.

The more we learn about PFAS contamination, the more we realize that the problem may be more widespread than we previously thought. Anvil 10+10,[4] a mosquito insecticide that has been aerially applied to considerably large portions of the United States, was recently found to contain PFAS. Further, emerging evidence suggests more pesticides and herbicides[5] may contain PFAS despite not being listed or disclosed through product safety data sheets (SDSs). We are already aware that land-applied biosolids, often to farmland, may contain PFAS. In the near future, we may need to sample incredibly wide geographic areas. Non-targeted PFAS analysis could be used to screen large areas, quickly identifying ‘hot zones’ that need to be investigated and characterized with more targeted and traditional PFAS analytical methods.

This method very well may be a cost-saving option that is recommended for site and property owners who are unsure of their risk.

Resources

[1] https://doi.org/10.1016/j.eti.2020.100915

[2]https://www.barrons.com/amp/articles/nation-s-pfas-leader-eurofins-expands-reporting-to-75-compounds-01614607351

[3]https://pfas-1.itrcweb.org/11-sampling-and-analytical-methods/#11_2

[4] https://www.epa.gov/pesticides/pfas-packaging

[5] https://www.eenews.net/stories/1063726787