EPA Method 533 for Analysis of Per/Polyfluoroalkyl Substances in Drinking Water Using Agilent 6470 Triple Quadrupole LC/MS

Significance of the topic

The analysis of per- and polyfluoroalkyl substances (PFAS) in drinking water has become critical due to their environmental persistence, widespread occurrence, and potential health impacts. Accurate quantitation at low concentrations is necessary for regulatory compliance and public safety. USEPA Method 533 addresses these demands by providing a validated protocol for measuring a broad range of PFAS compounds using solid-phase extraction coupled with triple quadrupole LC/MS/MS.

Objectives and study overview

This work presents a second-laboratory demonstration of EPA Method 533, using an Agilent 6470 Triple Quadrupole LC/MS system. The goals were to verify method performance for 25 targeted PFAS analytes (including C4–C12 acids, C4–C8 sulfonates, fluorotelomers, and perfluorinated ethers), assess accuracy and precision in reagent and tap water, and confirm achievable reporting limits relative to EPA requirements.

Methodology and instrumentation

Sample preparation:

• Volume: 250 mL water samples spiked with isotope-dilution analogs
• Extraction: Off-line weak anion-exchange SPE cartridges, elution with ammonium hydroxide/methanol, concentration to dryness, reconstitution in 80 % MeOH, addition of internal standards

Chromatography and mass spectrometry:

• LC: Agilent 1260 Infinity binary pump, autosampler, column compartment; analytical column ZORBAX Eclipse Plus C18 (3×50 mm, 1.8 µm), delay column ZORBAX SB-C18 (4.6×50 mm, 3.5 µm), 50 °C, injection volume 10 µL
• Mobile phase: A = 20 mM ammonium acetate in water, B = methanol; gradient from 5 % to 95 % B over 20 min at 0.4 mL/min
• MS: Agilent Jet Stream ESI in negative mode, dynamic MRM with optimized transitions (precursor/product ions, fragmentor and collision energies), cell accelerator voltage 2 V

Main results and discussion

Precision and accuracy:

• Reagent and tap water recoveries ranged 87–103 % for all compounds
• Relative standard deviations ≤5 % in reagent water and ≤12 % in tap water, meeting EPA criteria

Reporting limits and background:

• Laboratory reagent blanks showed minimal PFAS background, confirming system cleanliness
• Single-lab minimum reporting limits (LCMRLs) for 22 of 25 analytes were ≤1 ng/L; all except PFHpA were below EPA targets

Chromatographic performance:

• Baseline resolution achieved for all compounds within each class without retention overlap
• Delay column effectively removed PFAS background from system plumbing

Benefits and practical applications

This validated protocol enables water testing laboratories to reliably quantify trace PFAS levels in drinking water, supporting regulatory compliance and risk assessment. The use of isotope-dilution internal standards ensures robust quantitation, while flexible LC conditions allow adaptation to different instrument platforms.

Future trends and potential applications

Continued method expansion may include emerging PFAS structures and shorter-chain analytes. Advances in high-resolution MS and automated SPE could further lower reporting limits and increase throughput. Integration with rapid screening techniques and data analytics will enhance large-scale environmental monitoring.

Conclusion

Agilent’s demonstration of EPA Method 533 confirms its accuracy, precision, and sensitivity for a diverse PFAS panel in drinking water. The approach meets or exceeds EPA performance requirements and provides a reliable framework for regulatory laboratories. Adoption of this workflow supports consistent PFAS monitoring and informed water quality management.

Used instrumentation

• Agilent 6470 Triple Quadrupole LC/MS with Jet Stream ESI source
• Agilent 1260 Infinity binary pump, autosampler, and column compartment
• Analytical column: ZORBAX Eclipse Plus C18, delay column: ZORBAX SB-C18

References

• USEPA Method 533 for Analysis of PFAS in Drinking Water, EPA Publication 533, 2020
• Agilent Application Note 5991-7951: Optimizer Software for dMRM Transition Tuning