CASE STUDY 3: Quantitative and Qualitative Analysis of Perfluoroalkyl Substances (PFASs) in Wildlife Samples Using the Xevo G2-XS Q-Tof

Importance of the Topic

Perfluoroalkyl substances (PFASs) are widely used fully fluorinated compounds with exceptional hydro- and lipophobic properties. Their extensive application in consumer goods and industrial processes has led to persistent contamination of the environment and wildlife. Regulatory and research efforts demand methods capable of detecting and characterizing PFASs at sub-ppb levels to assess exposure risks and support mitigation strategies.

Objectives and Study Overview

The primary aim was to demonstrate a robust workflow for both quantitative and qualitative analysis of PFASs in wildlife tissues using high-resolution, data independent mass spectrometry (MS E) on the Xevo G2-XS Q-Tof. An integrated software platform (UNIFI Scientific Information System) was used to streamline data review, historical re-interrogation, and reporting. Authentic mink liver extracts were used to validate performance at trace concentration levels.

Methodology and Workflow

Samples and standards preparation

• PFAS solvent standards were diluted from a PFC Analysis Kit mixture
• Mink liver extracts were provided pre-extracted, stored, and diluted 1:10 in methanol

Chromatography and system modification

• ACQUITY UPLC I-Class with BEH C18 columns (analytical and isolator) maintained at 55 °C
• PEEK tubing and an isolator column introduced to eliminate PTFE-derived PFAS background
• Water/methanol mobile phases buffered with ammonium acetate
• Gradient elution over 8.5 min at 0.65 mL/min

Mass spectrometry

• Xevo G2-XS Q-Tof operating in negative ESI
• Data independent acquisition (MS E) with low and elevated collision energies
• Mass range 50–1200 m/z, scan time 0.2 s
• Lock mass correction using leucine enkephalin

Data processing

• UNIFI workflows defined for screening, identification, and quantification
• Compound lists imported from a user-curated scientific library
• Fragment Match algorithm assigned structure-specific product ions
• Historical data review enabled by updateable target lists

Used Instrumentation

• ACQUITY UPLC I-Class System
• ACQUITY UPLC BEH C18 Column (2.1 x 50 mm, 1.7 μm)
• Xevo G2-XS Q-Tof Mass Spectrometer
• Waters PFC Analysis Kit with isolator column and PEEK tubing
• UNIFI Scientific Information System

Main Results and Discussion

Eleven PFAS analytes (carboxylic and sulfonic acids) achieved limits of detection down to 0.01–0.25 ng/mL and LOQs at 0.05–0.5 ng/mL, with linear dynamic ranges spanning 0.05 to 25 ng/mL and correlation coefficients (R2) above 0.99. High resolution full-scan MS and elevated-energy spectra provided multiple exact mass product ions per compound. Chromatographic peak widths were ~6 s with 12–15 data points at base. Co-eluting matrix components such as bile acids were distinguished by accurate mass differences (e.g., PFOS vs taurodeoxycholate). UNIFI workflows enabled one-click visualization of calibration curves, concentration calculations, extracted ion chromatograms, and fragment confirmation.

Benefits and Practical Applications

• Simultaneous targeted and non-targeted screening without reprocessing
• Comprehensive fragment information for structural confirmation
• Historical data review for emerging contaminants
• Reduced PFAS background through hardware modifications
• Streamlined reporting via customizable software workflows

Future Trends and Opportunities

Continuous expansion of scientific libraries will support the identification of novel or emerging PFASs. Integration of suspect- and non-targeted screening methods with AI-driven annotation could accelerate discovery of transformation products. Applications may extend to additional matrices such as blood, water, and sediments. Advances in instrumentation sensitivity and software interoperability will further enhance routine monitoring and forensic investigations.

Conclusion

The described workflow using the Xevo G2-XS Q-Tof and UNIFI platform delivers sensitive, high-confidence qualitative and quantitative analysis of PFASs in wildlife samples. Key advantages include sub-ppb detection, full-scan fragment data, effective background suppression, and efficient data review. This integrated approach meets the demands of environmental monitoring and regulatory compliance.

Reference

1. Buck RC et al. Integrated Environmental Assessment and Management 2011, 7, 513–541
2. Benskin JP et al. Analytical Chemistry 2007, 79, 6455–6464
3. Waters White Paper 720004036en, October 2011
4. Kärrman A et al. Environ Pollut Res 2010, 3, 750–758
5. Waters Application Note 720002813en, November 2008
6. Waters Application Note 720005436en, July 2015
7. Waters White Paper 720004597en, April 2013