New Semiquantification Strategy Developed for Estimating Suspect PFAS Concentrations

Researchers at Oregon State University have developed a practical semiquantification strategy for estimating suspect per- and polyfluoroalkyl substance (PFAS) concentrations in complex mixtures.

The traditional 1:1 matching strategy requires expert knowledge to select calibrants based on head group, fluorinated chain length, and retention time, making it a time-consuming process. A lack of uniformity in calibrant selection among different laboratories also makes comparing reported suspect concentrations challenging.

In this study, the area counts for 50 anionic and five zwitterionic/cationic target PFAS were used to create “average PFAS calibration curves” for suspects detected in negative- and positive-ionization mode liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS). The calibration curves were fitted with log-log and weighted linear regression models and were evaluated for their accuracy and prediction interval in predicting the target PFAS concentrations.

The researchers then used the average PFAS calibration curves to estimate the suspect PFAS concentration in a well-characterized aqueous film-forming foam. Weighted linear regression resulted in more target PFAS that fell within 70–130% of their known standard value and narrower prediction intervals than the log-log transformation approach. The suspect PFAS concentrations calculated by both weighted linear regression and log-log transformation were within 8–16% of those estimated by a 1:1 matching strategy.

The new semiquantification strategy can be easily expanded and applied to any suspect PFAS, even if the confidence in the suspect structure is low or unknown. It provides a practical and efficient way to estimate suspect PFAS concentrations, which will aid in the monitoring and regulation of these potentially harmful chemicals in the environment.

Reference

(1) Cao, D.; Schwichtenberg, T.; Duan, C.; Xue, L.; Muensterman, D.; Field, J. Practical Semiquantification Strategy for Estimating Suspect Per- and Polyfluoroalkyl Substance (PFAS) Concentrations. J. Am. Soc. Mass Spectrom. 2023, ASAP. DOI: 10.1021/jasms.3c00019