THE UTILITY OF CYCLIC ION MOBILITY TO IMPROVE SELECTIVITY AND ANALYSIS EFFICIENCY OF ENVIRONMENTAL PFAS CONTAMINATION AND EXPOSURE

Importance of the Topic

Contamination by per‐ and polyfluoroalkyl substances (PFAS) poses significant environmental and human health concerns due to their persistence, bioaccumulation, and potential carcinogenicity. Accurate separation and identification of PFAS isomers in complex matrices are critical for exposure assessment and risk management.

Objectives and Study Overview

This study evaluates cyclic ion mobility (cIM) coupled with liquid chromatography–mass spectrometry (LC‐cIM‐MS) to enhance selectivity, reduce analysis time, and improve identification confidence for PFAS and isobaric biomarkers. A cross‐site and cross‐technology comparison against drift tube (DT) ion mobility CCS values was performed to validate reproducibility.

Methodology and Instrumentation

Human serum samples were subjected to solid‐phase extraction using SPE 96‐well µElution plates with mixed‐mode sorbent. Reversed‐phase UPLC separation employed a Waters ACQUITY UPLC I‐Class Premier system using Atlantis BEH C18 AX and HSS T3 columns under a 95:5 H₂O/MeOH gradient. Ion mobility analysis was conducted on a SELECT SERIES Cyclic IMS mass spectrometer with T‐wave IMS at resolution up to 145. Data processing utilized MassLynx v4.2, Driftscope 3.0, Waters_connect 3.8.0.23, and Tibco Spotfire 6.0.0.

Used Instrumentation

• Waters ACQUITY UPLC I‐Class Premier system with PFAS Kit
• ACQUITY UPLC Atlantis Premier BEH C18 AX column (2.1 × 50 mm, 5 µm)
• ACQUITY UPLC HSS T3 column (2.1 × 100 mm, 1.8 µm)
• SELECT SERIES Cyclic IMS mass spectrometer
• MassLynx, Driftscope, Waters_connect, Tibco Spotfire software

Main Results and Discussion

Cyclic ion mobility enabled full resolution of linear and branched PFOS and perfluoroalkyl carboxylic acid isomers, with CCS reproducibility within Δ<1% relative to DT values. Coeluting cholic acid biomarkers were differentiated. Quantitative linearity (R² >0.999) was demonstrated from 5 pg/mL to 10 000 pg/mL. Combining CCS, retention time, and m/z enhanced specificity for non‐targeted PFAS screening.

Benefits and Practical Applications

• Improved selectivity for isomeric PFAS and biomarker species
• 75% reduction in analysis time via shortened UPLC gradients
• Reproducible CCS as an orthogonal identification metric
• Potential to link isomer structures with toxicity and exposure pathways

Future Trends and Applications

Wider adoption of cyclic ion mobility in routine PFAS monitoring is expected, driven by its high throughput and specificity. Advancements will include integration with high‐definition MSE, expansion of CCS reference libraries, automated data workflows, and multimodal separation techniques for improved structural elucidation.

Conclusion

LC‐cIM‐MS offers a robust platform for rapid, reproducible separation and identification of PFAS and isobaric biomarkers. CCS measurements provide a reliable, complementary descriptor that enhances analytical confidence and supports comprehensive exposure assessment.

References

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2. Schilberg RN, Wei S, Twagirayezu S, Neill JL. Conformational dynamics of perfluorooctanoic acid (PFOA) studied by molecular rotational resonance spectroscopy. Chemical Physics Letters. 2021;778:138789.
3. Organtini KL, Rosnack KJ, Lame ME, Calton LJ. Extracting and Analyzing PFAS from Human Serum. Waters Application Note 720007114. 2021.
4. Waters Corporation. PFAS Analysis Kit for ACQUITY UPLC Systems User Guide 720006689. 2021.