Approaches to Non-targeted Analyses of Per- and Polyfluoroalkyl Substances (PFAS) in Environmental Samples : Waters

Perand polyfluoroalkyl substances (PFAS) are a group of synthetic compounds that are used in a variety of industrial applications and consumer products and are known environmental pollutants. Targeted methods using tandem quadrupole mass spectrometers provide sensitive detection for these compounds, but focus on a limited number of potential PFAS that could be detected. A non-targeted technique provides a more comprehensive characterization of PFAS contamination in a sample. In this study, workflows for nontargeted analyses for PFAS are demonstrated using a Xevo G2-XS QTof coupled with an ACQUITY UPLC IClass PLUS modified with PFAS kit components. In-house PFAS reference libraries were used to assign putative identities to the compounds detected in wastewater and soil samples. The libraries consisted of accurate masses of molecular ions, fragment ions, isotope patterns and, in cases where reference standards are available, additional chromatographic properties such as retention times, which were used to confidently assign putative identifications to the components. PFAS components detected in the wastewater and soil samples were subsequently quantified using a similar workflow. Discovery of PFAS not present in the UNIFI libraries can be achieved by automatic searching of external databases, aided using additional software tools including common fragments, neutral loss, and mass defect searching. The presented non-targeted methodology can be useful in various scenarios including, but not limited to, discovery of novel PFAS compounds, a better understanding of PFAS contamination in the environment, and source fingerprinting for remediation purposes. Benefits The direct injection approach provides a simplified sample preparation technique to avoid loss of PFAS and biased results ■ Local PFAS accurate mass libraries with over 4,000 compounds that are easily customizable ■ An analytical solution that uses multiple attributes for component putative identification increasing confidence in the results for legacy and emerging PFAS in environmental samples ■