Analysis of PFAS in Potable Water by Direct Injection Using the LCMS-8060NX

Importance of the Topic

Per- and polyfluoroalkyl substances (PFAS) are widely used in industrial and consumer applications and have become emerging contaminants in drinking water sources. Their persistence, bioaccumulation potential, and links to health effects such as carcinogenicity, developmental disruption, and immune dysfunction have prompted regulatory limits at the low ng/L level. Reliable, sensitive, and rapid analytical methods are essential for routine monitoring of potable water to ensure compliance and protect public health.

Study Objectives and Overview

This study presents a direct injection liquid chromatography–tandem mass spectrometry (LC-MS/MS) method using the Shimadzu LCMS-8060NX system for the quantitation of 23 PFAS in purified water. The goals were to achieve limits of quantitation (LoQs) between 1 and 5 ng/L, obtain linear calibration curves with correlation coefficients >0.99, and streamline sample preparation to enhance laboratory throughput.

Methodology

The method employed direct injection of filtered water samples without extraction or concentration steps. Key elements include:

• Negative electrospray ionization in multiple reaction monitoring (MRM) mode.
• Use of isotopically labeled internal standards for normalization.
• Fast gradient UHPLC (7 min total run) with 20 mM ammonium acetate in water (A) and acetonitrile (B).
• Calibration curves prepared in blank matrix spiked over the range of expected concentrations.
• Evaluation of filtration effects using 0.22 µm PVDF filters.

Used Instrumentation

The analysis was carried out on:

• UHPLC: Shimadzu Nexera™ XS system.
• Mass spectrometer: Shimadzu LCMS-8060NX triple quadrupole.
• Delay column: XRODS (30 × 3.0 mm, 2.2 µm).
• Analytical column: XRODS III (50 × 2.0 mm, 1.6 µm).
• Source parameters: HESI negative mode, interface voltage –0.5 kV, drying gas 8 L/min, nebulizing gas 2.5 L/min, heat block 200 °C, DL temperature 120 °C.
• Flow rate: 0.35 mL/min; injection volume: 100 µL; column temperature: 40 °C.

Main Results and Discussion

The method yielded linear calibration curves for all 23 PFAS, with R² values exceeding 0.99 for most analytes (PFDS R² = 0.985). LoQs ranged from 1 to 5 ng/L. Filtration with PVDF filters introduced variable analyte losses (differences from 0 % to 167 %), highlighting the importance of filter material selection. Chromatographic separation achieved retention times between 1.2 min and 4.4 min, enabling a rapid 7 min cycle time. Direct injection produced reproducible area ratios and consistent quantitation at low ng/L levels without manual cleanup or enrichment.

Benefits and Practical Applications

The developed method offers:

• A streamlined workflow with no sample pretreatment.
• High sensitivity meeting regulatory requirements for drinking water.
• Fast turnaround suitable for high-throughput monitoring.
• Robust quantitation using isotope dilution to compensate for matrix effects.

Future Trends and Opportunities

Emerging directions include:

• Expansion to a broader range of novel and ultra-short chain PFAS.
• Integration of high-resolution MS for non-target screening.
• On-site portable LC-MS for real-time water quality assessment.
• Automated sample handling and data processing to further increase throughput.
• Continuous adaptation to evolving regulatory standards and health guidelines.

Conclusion

This work demonstrates a rapid, reliable, and sensitive direct injection LC-MS/MS method for quantifying 23 PFAS in potable water at ng/L levels using a simple Shimadzu LCMS-8060NX configuration. The approach meets stringent regulatory requirements while minimizing sample preparation, making it well suited for routine environmental and compliance laboratories.

References

1. Peritore AF, et al. Analysis of PFAS in drinking water. Int J Mol Sci. 2023;24(14):11707.
2. US EPA. Our Current Understanding of the Human Health and Environmental Risks of PFAS. 2023.
3. Centers for Disease Control and Prevention. PFAS Factsheet. 2022.
4. US EPA. Final PFAS National Primary Drinking Water Regulation. 2024.