Testing for PFAS Analysis in Aquatic Environments

A team of scientists from China and Sweden are testing different methods for analyzing per- and polyfluoroalkyl substances (PFAS) in aquatic environments, publishing their work in TrAC Trends in Analytical Chemistry (1).

Beautiful yellow Water lily (nuphar lutea) in the clear pound. Underwater shot in the lake. Nature habitat. | Image Credit: © Rostislav - stock.adobe.com

PFAS have been used for decades in various industrial and consumer products and create great risk to the environment and human health because of their inability to break down (2). PFAS are typically used in non-stick, water-repellent, and fire-resistant materials. While efforts have been made since the 1990s to detect PFAS, there is still a lot unknown about these substances and their potential impact.

In this study, the scientists chose to analyze PFAS in aquatic environments. Normally, extractable organofluorine (EOF) or adsorbable organofluorine (AOF) are used to address PFAS. However, aquatic environments hold a limited amount of natural organofluorine (OF) sources, meaning that most OFs in water samples stem from anthropogenic sources. To better understand organofluorine (UOF) profiles, nontarget and suspect screening were applied using high-resolution mass spectrometry (HRMS) techniques, while some also considered applying the oxidative conversion method to measure oxidizable precursors that could transform into perfluorocarboxlylic acids (PFCAs). According to the scientists, combining these methods could help build a better picture of PFAS pollution in aquatic environments.

The techniques used in this experiment each had advantages and disadvantages. Target analysis, which is typically used for PFAS analysis, proved to be the most sensitive, convenient, and accurate of the four; however, it also had low inclusivity and delivered less comprehensive results. EOF analysis holds high inclusivity, which supports target analysis and enables the process to provide a complete PFAS profile and detect high amounts of UOF in water samples. The oxidative conversion method can also be applied to this process, but it does not effectively identify non-oxidizable emerging PFAS.

The scientists said it is important to consider many targets in future PFAS analysis, including emerging PFAS — PFAS isomers, ultrashort-chain PFAS, and cationic and zwitterionic PFAS — to measure large unknown PFAS fractions more effectively.

References

(1) Wang, Q.; Ruan, Y.; Yuen, C. N. T.; Lin, H.; Yeung, L. W. Y.; Leung, K. M. Y.; Lam, P. K. S. Tracing per- and polyfluoroalkyl substances (PFASs) in the aquatic environment: Target analysis and beyond. Trends Analyt. Chem. 2023, 169, 117351. DOI: https://doi.org/10.1016/j.trac.2023.117351

(2) Workman Jr, J. Are “Forever Chemicals” Really Forever? LCGC 2023. https://www.chromatographyonline.com/view/forever-chemicals-pfas-perfluoroalkyl-polyfluoroalkyl-substances (accessed 2023-11-30)