Accurate Mass Library for PFAS Analysis in Environmental Samples and Workflow for Identification of Pollutants in Drinking Water Using GC/Q-TOF

Significance of the Topic

The persistence and bioaccumulation of per- and polyfluoroalkyl substances in environmental and drinking water samples pose significant health and regulatory challenges. Accurate mass libraries enable high-confidence detection and broaden the scope of monitored PFAS compounds, improving sensitivity and reliability compared to conventional non-target screening.

Objectives and Study Overview

This work describes the development of a comprehensive accurate mass Personal Compound Database and Library of over 150 GC-amenable PFAS spectra for the Agilent 7250 GC/Q-TOF system. The study evaluates both targeted and non-targeted workflows for identifying PFAS and other pollutants in drinking water extracts from two California sources.

Methodology and Instrumentation

Water samples from Weaverville (surface) and Irvine (mixed source) were extracted by multimode SPE (HLB, WAX, WCS, Isoelut ENV) and solvent-exchanged to ethyl acetate prior to GC/Q-TOF analysis. Key instrumentation and software included:

• Agilent 8890 GC with Agilent DB-624 UI and DB-5ms UI columns
• Agilent multimode inlet with ultra inert liners
• Agilent 7250 GC/Q-TOF mass spectrometer under electron ionization at 70 eV
• Helium carrier gas at constant flow (1–1.2 mL/min)
• MassHunter Qualitative Analysis, Unknowns Analysis (SureMass), Quantitative Analysis Screener, PCDL Manager, ChemVista and Mass Profiler Professional software

Main Results and Discussion

The PFAS PCDL contains accurate mass fragments, retention times and indices for diverse classes including fluorotelomer alcohols, olefins, acrylates, carboxylic acids and sulfonamides. Over 50 percent of PFAS spectra were unique compared to NIST23. Both non-targeted and targeted GC/Q-TOF workflows detected methyl perfluorooctanoate in drinking water, confirming conversion of perfluorocarboxylic acids to methyl esters. Non-target screening against PFAS, pesticide, NIST23 and MassBank.us libraries identified more than 100 additional contaminants such as disinfection by-products (halomethanes, haloacetic acids), industrial chemicals, PAHs and pesticides. Accurate mass filtering and retention index matching effectively removed false positives from unit-mass libraries.

Benefits and Practical Applications

This accurate mass library approach enhances PFAS monitoring by providing:

• Higher confidence in compound identification through combined accurate mass and retention index matching
• Improved sensitivity and flexibility in targeted and non-targeted screening
• Automated workflows (GC/Q-TOF Screener) that reduce manual data review time

Future Trends and Applications

Integration of predictive retention index models and further expansion of accurate mass libraries will facilitate identification of emerging PFAS and other pollutants. Coupling high-resolution GC/Q-TOF with orthogonal techniques and real-time monitoring systems promises enhanced environmental surveillance and regulatory compliance.

Conclusion

The developed accurate mass PFAS library for GC/Q-TOF significantly expands the detection capabilities for both known and unknown contaminants in drinking water. When combined with high-resolution workflows and retention index matching, it delivers a robust platform for routine environmental monitoring and research.

References

1. Poly and Perfluoroalkyl Substances PFAS Overview and Current Activities Environmental Protection Agency
2. Hammer J Endo S Volatility and Nonspecific van der Waals Interaction Properties of PFAS Environ Sci Technol 2022 56 15737-15745
3. Liu X Understanding Semi-volatile Organic Compounds SVOCs in Indoor Dust Indoor Built Environ 2022 31 291-298
4. Del Vento S et al Volatile PFAS in the Western Antarctic Peninsula Atmos Pollut Res 2012 3 450-455
5. Wohlgemuth G et al SPLASH a Hashed Identifier for Mass Spectra Nat Biotechnol 2016 34 1099-1101
6. Agilent ChemVista Library Manager Technical Overview 5994-5924EN 2023
7. Valdiviez L Fiehn O Nieto S Differences in Metabolic Profiles in Heart Failure High-Resolution GC/Q-TOF Agilent Technologies 2023
8. Van Gansbeke W et al Semi-Automated GC/Q-TOF Screening with AssayMAP Bravo for Antidoping Agilent Technologies 2023
9. Hanari N et al Variation in Concentration of PFOA in Methanol Solutions During Storage Chemosphere 2014 94 116-120