Molecular detection of per- and polyfluoroalkyl substances in water using time-of-flight secondary ion mass spectrometry

Xiao-Ying Yu; Cuiyun Yang; Jun Gao; John Xiong; Xiao Sui; Lirong Zhong; Yuchen Zhang; Jiyoung Son

doi:10.3389/fchem.2023.1253685

Molecular detection of per- and polyfluoroalkyl substances in water using time-of-flight secondary ion mass spectrometry

Front Chem. 2023 Oct 6:11:1253685. doi: 10.3389/fchem.2023.1253685. eCollection 2023.

Authors

Xiao-Ying Yu¹, Cuiyun Yang^#¹, Jun Gao^#¹, John Xiong², Xiao Sui³, Lirong Zhong⁴, Yuchen Zhang¹, Jiyoung Son⁴

Affiliations

¹ Oak Ridge National Laboratory, Materials Science and Technology Division, Oak Ridge, TN, United States.
² Haley & Aldrich Inc., Costa Mesa, CA, United States.
³ College of Geography and Environment, Shandong Normal University, Jinan, China.
⁴ Pacific Northwest National Laboratory, Energy and Environment Directorate, Richland, WA, United States.

^# Contributed equally.

Abstract

Detection of per- and polyfluoroalkyl substances (PFASs) is crucial in environmental mitigation and remediation of these persistent pollutants. We demonstrate that time-of-flight secondary ion mass spectrometry (ToF-SIMS) is a viable technique to analyze and identify these substances at parts per trillion (ppt) level in real field samples without complicated sample preparation due to its superior surface sensitivity. Several representative PFAS compounds, such as perfluorooctanesulfonic acid (PFOS), perfluorobutanoic acid (PFBA), perfluoropentanoic acid (PFPeA), perfluoheptanoic acid (PFHpA), and perfluorononanoic acid (PFNA), and real-world groundwater samples collected from monitoring wells installed around at a municipal wastewater treatment plant located in Southern California were analyzed in this work. ToF-SIMS spectral comparison depicts sensitive identification of pseudo-molecular ions, characteristic of reference PFASs. Additionally, principal component analysis (PCA) shows clear discrimination among real samples and reference compounds. Our results show that characteristic molecular ion and fragments peaks can be used to identify PFASs. Furthermore, SIMS two-dimensional (2D) images directly exhibit the distribution of perfluorocarboxylic acid (PFCA) and PFOS in simulated mixtures and real wastewater samples. Such findings indicate that ToF-SIMS is useable to determine PFAS compounds in complex environmental water samples. In conclusion, ToF-SIMS provides simple sample preparation and high sensitivity in mass spectral imaging, offering an alternative solution for environmental forensic analysis of PFASs in wastewater in the future.

Keywords: PFAS; PFOs; ToF-SIMS; groundwater; molecular identification; wastewater.

Grants and funding

X-YY is indebted to the support of the strategic Laboratory Directed Research and Development of the Physical Sciences Directorate of the Oak Ridge National Laboratory (ORNL). CY is grateful for support from the Chinese National Scholarship and Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology (LMEES2010809). JX thanks Department of Defense Environmental Security Technology Certification Program (project number ER21-5153) for support. X-YY thanks the SERDP WP 18-1660 for partial support of initial analysis. Pacific Northwest National Laboratory is operated for the U.S. Department of Energy (DOE) by Battelle Memorial Institute under Contract No. DE-AC05-76RL01830. ORNL is managed by UT-Battelle, LLC, for the U. S. DOE under contract number DE-AC05-00OR22725. This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. DOE. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan).