Advancing PFAS Detection in Drinking Water: GC-MS as a Complementary Technique to LC-MS for Closing PFAS Mass Balance

Significance of the Topic

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants with diverse physico-chemical properties. Standard LC-MS methods do not effectively cover volatile PFAS compounds, creating analytical gaps and hindering accurate PFAS mass balance assessments in drinking water.

Objectives and Study Overview

This study aimed to develop and validate a head-space solid-phase microextraction (HS-SPME) coupled with triple quadrupole gas chromatography-mass spectrometry (GC-MS/MS) method for the quantitative analysis of 13 volatile PFAS targets in drinking water. The performance was evaluated in reagent water, surface water-derived drinking water, and private well samples.

Methodology

• Sample preparation: 10 mL water, 2 % NaCl addition, direct HS-SPME extraction.
• SPME fiber: 50/30 µm DVB/CAR/PDMS.
• Extraction: 30 min at 50 °C, agitation at 300 rpm.
• Desorption: 7 min at 240 °C.
• Calibration: Isotope-dilution over 1–2000 ng/L with seven-point curve and internal standards spiked at 100 ng/L.

Instrumentation

• Gas chromatograph: Shimadzu Nexis GC-2030.
• Mass spectrometer: Shimadzu GCMS-TQ8040 NX in MRM mode.
• Autosampler: AOC-6000 Plus with HS-SPME module.
• Column: SH-I-624Sil MS Capillary, 30 m × 0.25 mm ID × 1.40 µm.

Main Results and Discussion

• Blanks confirmed free of PFAS interferences.
• Calibration linearity: R² ≥ 0.994 for all analytes.
• Recoveries: 64–129 % across matrices, intra-batch RSD ≤ 4.9 %.
• Laboratory control sample (LCS) precision: recoveries 76–128 %, RSD ≤ 8.9 %.
• No significant matrix effects observed in private well or surface-water-derived drinking water.

Benefits and Practical Applications of the Method

• Minimal sample preparation without solvent extraction.
• Quantitative detection of volatile PFAS at nanogram-per-liter levels.
• Complements LC-MS workflows to expand PFAS coverage.
• Applicable for routine drinking water monitoring and regulatory compliance.

Future Trends and Potential Applications

• Expanding the target list to include emerging and transformation PFAS products.
• Integration with high-resolution MS for non-target screening.
• Automation and field-deployable SPME sampling devices for on-site analysis.
• Combined LC-MS/GC-MS platforms for comprehensive PFAS mass balance studies.

Conclusion

The developed HS-SPME GC-MS/MS method demonstrates robust sensitivity, precision, and accuracy for volatile PFAS in drinking water. By addressing analytical gaps left by LC-MS, this approach enhances the overall PFAS mass balance and supports comprehensive environmental monitoring.