Handbook of Analysis Procedures for EPA method 533

Importance of the topic

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants that pose health risks at trace levels in drinking water. Reliable detection methods are essential for regulatory compliance and public safety.

Objectives and overview of the method

This study presents detailed procedures for EPA Method 533, covering initial demonstration of capability (IDC) and routine analysis of 29 PFAS in drinking water. Key objectives include establishing minimum reporting levels (MRLs), validating calibration curves, and ensuring ongoing quality control (QC).

Methodology and instrumentation

• Solid-phase extraction (SPE) using anion-exchange cartridges with phosphate buffer and ammonium acetate rinses.
• Elution of PFAS with ammonium hydroxide in methanol, followed by nitrogen blowdown and reconstitution in 80:20 methanol:water.
• Liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) employing isotope-dilution internal standards for quantitation.

Used instrumentation

• Automated SPE manifold and vacuum pump
• Nitrogen evaporative concentrator (55–60 °C)
• High-performance LC system with binary pump
• Triple quadrupole mass spectrometer with electrospray ionization

Main results and discussion

• Calibration curves with ≥5 points forced through zero demonstrated linearity across MRL to upper range.
• System blanks showed PFAS levels below one-third of MRL, confirming low background.
• MRL confirmation and calibration verification met QC limits (50–150% at MRL, 70–130% at mid-range).
• Precision (RSD ≤ 20%) and accuracy (recoveries 70–130%) were achieved for both laboratory fortified blanks and matrices.
• Branched isomeric PFAS were successfully separated within expected MRM windows.

Benefits and practical applications

The outlined protocol ensures robust, reproducible quantification of PFAS in drinking water for regulatory monitoring, quality assurance, and research applications. The isotope-dilution approach corrects for matrix effects and instrument variability.

Future trends and possibilities

• Automation of SPE and sample handling to increase throughput.
• Expansion of target lists to emerging PFAS and transformation products.
• Integrating high-resolution mass spectrometry for non-target screening.
• Miniaturized sampling techniques for in-field analysis.

Conclusion

EPA Method 533 with SPE and LC-MS/MS provides a validated, sensitive approach for PFAS analysis in drinking water. Adherence to IDC and stringent QC criteria ensures data reliability for environmental monitoring and public health protection.

References

• EPA Method 533: Determination of Per- and Polyfluoroalkyl Substances in Drinking Water by Isotope Dilution Anion Exchange SPE and LC-MS/MS.
• Shimadzu Corporation, Handbook of Analysis Procedures for EPA Method 533, C146-E465, 2022.