Determination of Per and Polyfluoroalkyl Substances in Drinking Water Using Agilent Bond Elut PFAS WAX SPE and LC/MS/MS

Significance of the Topic

Per and polyfluoroalkyl substances PFAS are persistent environmental contaminants that accumulate in water supplies and pose human health concerns. Reliable analytical methods are critical to monitor trace level PFAS concentrations in drinking water and meet regulatory requirements.

Objectives and Study Overview

This study evaluates the Agilent Bond Elut PFAS WAX solid phase extraction SPE cartridge for isolation of 25 EPA method 533 target PFAS and 26 additional analytes from drinking water. The goal was to demonstrate low background contamination, high analyte recovery, precise quantification at low ng per liter levels, and broad PFAS class coverage.

Methodology

The protocol followed EPA method 533. A 500 mg 6 mL Bond Elut PFAS WAX cartridge was conditioned with phosphate buffer. A 250 mL water sample amended with isotope dilution analogues was loaded, washed to remove matrix interferences, and eluted with 2 percent ammonium hydroxide in methanol. Eluates were dried under nitrogen, reconstituted in 80:20 methanol water, and analyzed by LC/MS/MS. Calibration used seven levels from 0.25 to 25 ng/mL with isotope dilution. Laboratory reagent blanks fortified blanks and quality control standards were assessed for background demonstration and method validation.

Instrumentation Used

• Agilent 1290 Infinity II LC system with high-speed pump multisampler and multicolumn thermostat
• InfinityLab PFAS-free delay column and ZORBAX RRHD Eclipse Plus C18 analytical column
• Agilent 6470B triple quadrupole LC/MS with Jet Stream electrospray source
• Agilent VacElut SPS 24 manifold for SPE processing

Main Results and Discussion

Blank cartridge evaluations by LC/Q-TOF showed substantially lower PFAS contamination compared to other commercial polymeric WAX phases. Calibration accuracy ranged from 73 to 129 percent across all levels with average accuracy near 100 percent. MRL confirmation at 2 ng/L met prediction interval criteria of 50–150 percent. Seven replicate midlevel spikes at 20 ng/L yielded 98.1 percent average recovery and 4.6 percent RSD for EPA 533 targets. An extended PFAS list achieved 99.0 percent recovery and 7.1 percent RSD. Drinking water matrix spikes confirmed accuracy above 90 percent. A PEG coelution interference in positive mode highlighted the importance of low-background sorbents to avoid signal enhancement in negative ion detection.

Benefits and Practical Applications of the Method

• Low ppt quantitation suitable for regulatory monitoring of PFAS in drinking water
• High recovery and reproducibility across diverse PFAS chemistries
• Minimized background interference through PFAS-optimized SPE materials
• Isotope dilution approach for accurate trace-level quantification

Future Trends and Applications

Emerging neutral and zwitterionic PFAS require advanced mixed-mode sorbents and high resolution mass spectrometry for comprehensive profiling. Automation of high-throughput SPE workflows will support large-scale monitoring. Expanding suspect and non-target screening using HRMS can reveal novel PFAS structures. Further improvements in cartridge design will continue to reduce contamination and improve selectivity for next generation PFAS analysis.

Conclusion

The Agilent Bond Elut PFAS WAX SPE cartridge coupled with LC/MS/MS provides a robust, accurate and sensitive method for determination of legacy and emerging PFAS in drinking water at low ppt levels. It meets or exceeds EPA method 533 performance criteria and offers expanded analyte coverage with minimal background and excellent precision.

Reference

1. US EPA Method 533 Determination of Per- and Polyfluoroalkyl Substances in Drinking Water by SPE and LC/MS/MS
2. US EPA Method 537 Determination of Selected Perfluorinated Alkyl Acids in Drinking Water by SPE and LC/MS/MS 2009
3. US EPA Draft Method 1633 Analysis of Per- and Polyfluoroalkyl Substances in Aqueous Solid and Tissue Samples by LC/MS/MS 2021
4. Bradman A et al Assessment of Methods to Collect and Analyze PFAS in Air Dust and Soil California Air Resources Board 2021
5. Li F et al Short-Chain Per- and Polyfluoroalkyl Substances in Aquatic Systems Occurrence Impacts and Treatment Chemical Engineering Journal 2020