To Speciate or Not to Speciate… That is the Question.

As PFAS industry professionals, we have seen the global adoption of speciated analytical methods in various regulatory frameworks, from the EPA and other organizations. These methods have been instrumental in protecting human health by achieving low-level detection and analyzing discrete PFAS compounds with the most common being as many as 40 unique compounds to date. 

While these methods are effective, they are not without limitations including:

• • The best modified 1633 methods detect up to ~40 compounds. However, depending on how you define PFAS, there are anywhere from 15,000 to 900,000 of them.

• • With thousands of unique PFAS compounds and more being added routinely to the list, speciated analysis is really only a small snapshot of what exists and may only be a small aperture of what the real PFAS story is for your samples. It calls into question how agencies will look at regulating the “other” PFAS compounds.

• • PFAS needs to be measured at incredibly low levels. The EPA has looked to regulate some forms of PFAS to be as low as 4 ppt (ng/L) which makes analysis incredibly difficult for these compounds.

• • Identifying one discrete chemical compound in the class across various forms of water matrices can result in significant error. In fact, interlab analysis studies for the 1633 method show recoveries as broad as +/- 70% which creates a challenge for generating accurate information.

This highlights the importance of understanding the benefits of non-speciated PFAS screening methods, when to use them, and where they too may fall short.

Benefits of Non-Speciated PFAS Screening Methods

Non-targeted PFAS screening methods are ideal for screening a broad PFAS picture, and technologies like the FRED-PFAS^TM field kit enable same-day, on-site results. Non-speciated analytical methods like his field kit and AOF, EOF, and TOF (Adsorbable, Extrable and Total Organic Fluorine respectively) offer reliable, quantitative indicators that can support decision-makers in various areas. For example, they enable:

• • The broadening of the aperture which captures a much broader range of PFAS 

• • Efficient PFAS contaminated site investigation and remediation project support

• • PFAS treatment technology efficacy and optimization 

• • Treatment train technology breakthroughs and troubleshooting support

• • Future-proofing projects and determining potential PFAS formation in forms unexpected

• • Evaluation of potential unanticipated sources or contributors to PFAS concentration that may not be part of the speciated lists

Where Non-Speciated Methods May Fall Short

While non-targeted methods are being trusted more and more by sophisticated consultants and technology providers, they are not ideal for all applications, including:

• • PFAS Forensics – Fingerprinting and characterization 

• • Regulatory Reporting – Customers often specify EPA methods 1633, 537.1, or 533 for state or federal agency reporting in the USA.

• • Potential False Positives – AOF and TOF may detect non-PFAS C-F bonds found in certain pesticides and pharmaceuticals which may or may not be an important consideration to your project.

• • Detection Limits – Certain total PFAS screening methods have higher detection limits (ppb levels).

• • Customer Hesitation – Customers may be reluctant to learn about additional PFAS compounds outside of their jurisdiction’s regulations.

• • Understanding Ultra Short Chain Speciation – Ultra short chains are less understood, and some total PFAS methods capture them, particularly TOF, which measures total fluorine mass.

• • Regulatory limit differences – Short chain PFAS are regulated at ppb levels while longer chains are regulated at ppt levels. It is always important to run speciated analysis to understand what your non-targeted method is saying at your site.