LC-MS/MS ANALYSIS OF LEGACY AND EMERGING PERFLUOROALKYL SUBSTANCES (PFAS) IN ENVIRONMENTAL WATER SAMPLES

Importance of the Topic

PFAS are persistent environmental pollutants used in various consumer and industrial applications. Their chemical stability and mobility make them challenging contaminants in water resources, necessitating highly sensitive analytical methods for monitoring and regulatory compliance.

Objectives and Study Overview

This work adapts and expands an SPE-LC-MS/MS protocol based on ISO 25101 to quantify 40 legacy and emerging PFAS compounds. The method was applied to four water matrices: surface water, groundwater, influent wastewater, and final effluent.

Methodology and Instrumentation

• Sample Preparation: Oasis WAX SPE cartridges (6 cc, 150 mg) provided 250× enrichment. Cartridges were conditioned with 0.5 % ammonia/methanol, methanol, and water; samples were acidified (pH < 3), loaded, rinsed with acetate buffer, and eluted with methanol and ammonia/methanol. Final extracts were concentrated to 0.5 mL.
• Chromatography: ACQUITY UPLC I-Class Plus with BEH C18 column (2.1×100 mm, 1.7 µm) at 35 °C. Mobile phases: A = 95:5 water:methanol + 2 mM ammonium acetate; B = methanol + 2 mM ammonium acetate; gradient elution over 22 min, 10 µL injection.
• Mass Spectrometry: Xevo TQ-S micro in ESI mode. Source at 100 °C, desolvation 350 °C (900 L/h), cone gas 100 L/h, capillary voltage 0.5 kV. MRM transitions optimized with QuanOptimize in MassLynx.

Main Results and Discussion

• Recovery and Repeatability: Internal standard–corrected recoveries ranged 75–130%; repeatability (six ground water replicates) showed RSDs <15%, mostly <10%.
• Detection Limits: Pre-enrichment LODs spanned <0.01 to 2 ng/L; all compounds exhibited linear calibration (R² >0.99).
• Instrument Robustness: Twenty replicate injections of spiked surface water demonstrated stable peak areas, retention times, and ion ratios with RSDs <10%.
• Environmental Screening: Diverse PFAS profiles were observed across sample types, highlighting both legacy (e.g., PFOA, PFOS) and emerging (e.g., GenX, ADONA) substances at varying concentration levels.

Benefits and Practical Applications

• Attains sensitivity to meet EPA (70 ng/L) and EU water directive requirements.
• Enables simultaneous quantification of a wide PFAS range, including emerging compounds.
• Provides a robust, reproducible workflow suitable for routine environmental and compliance monitoring.

Future Trends and Applications

Anticipated developments include automation of sample preparation, integration of non-targeted high-resolution screening, miniaturized SPE formats, and further lowering of detection limits for ultra-trace PFAS analysis.

Conclusion

The described SPE-LC-MS/MS method offers a reliable, high-throughput approach for the quantitative determination of both legacy and emerging PFAS in environmental waters, aligning with current regulatory guidelines and supporting comprehensive monitoring programs.

References

Organtini K, Rosnack K, Stevens D, Orens P, Brinster K. LC-MS/MS Analysis of Legacy and Emerging Perfluoroalkyl Substances in Environmental Water Samples. Waters Application Note 720006471EN.