Analysis of Per- and Poly-fluoroalkylated Substances (PFAS) Specified in EPA Method 1633 Using Triple Quadrupole LC-MS/MS

Significance of the Topic

Per- and polyfluoroalkyl substances (PFAS) represent a class of persistent environmental contaminants with significant human health and ecological impacts. Regulatory bodies, including the U.S. EPA, are establishing stringent limits for PFAS in water and solid matrices. Reliable, sensitive analytical methods are essential for monitoring these trace-level compounds and ensuring compliance.

Objectives and Study Overview

The primary aim of this work was to evaluate Shimadzu’s LCMS-8060NX triple quadrupole system in quantifying the 40 PFAS compounds specified in EPA Draft Method 1633. Key goals included:

• Assessing method sensitivity and linearity across a broad concentration range (0.3 ppt to 625 ppb).
• Verifying limits of quantitation (LOQ), detection limits (IDL, theoretical MDL), and precision criteria (%RSD, %RSE ≤ 20%).
• Demonstrating efficient data processing and reporting with LabSolutions Insight software.

Methodology and Instrumentation

Samples were prepared in silanized glass vials with low-adsorption caps. Chromatographic separation employed a Shim-pack Scepter C18 analytical column (2.1 × 50 mm, 3 µm) and a Shimadzu GIST C18 delay column to reduce background PFAS interferences. Gradient elution used 2 mM ammonium acetate in water (Phase A) and acetonitrile (Phase B) at 0.4 mL/min. Detection was performed in negative electrospray ionization MRM mode on the Shimadzu LCMS-8060NX. Data acquisition and review utilized Shimadzu LabSolutions Insight software.

Main Results and Discussion

• All target PFAS met sensitivity requirements, with signal-to-noise ratios above 10 at LOQ levels.
• Calibration curves exhibited excellent linearity (R²>0.99) across the tested range.
• Instrument detection limits (IDL) and theoretical method detection limits (MDL) were below EPA 1633 thresholds, often by an order of magnitude.
• Precision metrics (%RSD, %RSE) were consistently under 20% for all analytes.

Benefits and Practical Applications

• Meets or exceeds EPA 1633 performance demands for regulatory monitoring in wastewater, biosolids, and tissue.
• High throughput data processing with LabSolutions Insight enhances laboratory efficiency.
• Robust interferences management via delay column and inert sample vials improves data confidence.

Future Trends and Potential Applications

• Expansion to broader PFAS panels as regulations evolve.
• Application in complex environmental and biological matrices with further method validation.
• Integration with high-resolution MS techniques for non-targeted PFAS screening.
• Automation of sample preparation workflows to increase throughput.

Conclusion

The Shimadzu LCMS-8060NX platform, combined with optimized chromatographic separation and LabSolutions Insight software, reliably quantifies the 40 PFAS defined in EPA Draft Method 1633. The system demonstrates excellent sensitivity, precision, and data processing speed, supporting regulatory compliance and advanced environmental monitoring efforts.

Reference

1. United States Environmental Protection Agency. 3rd Draft Method 1633: Analysis of Per- and Polyfluoroalkyl Substances (PFAS) in Aqueous, Solid, Biosolids, and Tissue Samples by LC/MS/MS, Office of Water, 2022.