Analysis of Per/Polyfluoroalkyl Substances (PFAS) in Drinking Water by EPA 537.1 and EPA 533 Using the Agilent Ultivo Triple Quadrupole LC/MS

Significance of the Topic

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants found in water sources worldwide. Their resistance to degradation and potential health impacts at trace levels have prompted stringent regulations and the need for ultra-trace analytical methods. Monitoring PFAS in drinking water is essential for public health and compliance with EPA guidelines.

Objectives and Study Overview

This work presents a commercial lab evaluation of EPA Method 537.1 (targeting 18 PFAS) and the newer EPA Method 533 (covering 25 PFAS) using the Agilent Ultivo triple quadrupole LC/MS system. Key goals included reducing analysis time, maintaining or improving sensitivity and reproducibility, and demonstrating method applicability for routine drinking water testing.

Methodology and Instrumentation

Sample Preparation:

• 250 mL drinking water samples spiked with isotopically labeled surrogates.
• Preservation with antimicrobial and dechlorinating agents per EPA protocols.
• SPE extraction, evaporation to 1 mL, reconstitution in appropriate methanol/water ratios.
• Final extracts analyzed by LC/MS/MS.

Instrumentation

• LC: Agilent 1290 Infinity II with a Poroshell EC-120 delay column and analytical column at 55 °C; run time 9 min plus 2.5 min post time; flow rate 0.7 mL/min; injection volumes of 4 µL for EPA 537.1 and 7 µL for EPA 533.
• MS: Agilent Ultivo triple quadrupole, negative ESI; optimized source settings; dynamic MRM acquisition with compound-specific transitions to ensure selectivity and sensitivity.

Key Results and Discussion

Chromatographic Performance:

• Complete baseline separation of PFAS with asymmetry factors within EPA criteria.
• Analysis time reduced to less than 10 minutes, enabling higher throughput compared to over 20 minutes in standard EPA methods.
• Delay column effectively minimized background PFAS contamination and carryover.

Recovery and Reproducibility:

• Recoveries for all PFAS ranged between 70 % and 130 % in reagent and finished drinking water.
• Relative standard deviations (RSDs) were below 20 % for both methods.

Sensitivity and Reporting Levels:

• Method detection limits for PFAS were below 1 ng/L for all analytes, surpassing EPA-specified reporting levels.
• The system achieved these limits despite using lower injection volumes than prescribed in the original methods.

Benefits and Practical Applications

• High-throughput PFAS monitoring with run times under 10 minutes.
• Robust performance meeting or exceeding EPA method requirements for sensitivity, accuracy, and precision.
• Reduced solvent and sample carryover due to optimized plumbing and delay column use.
• Scalable approach for commercial and regulatory laboratories tasked with routine PFAS analysis.

Future Trends and Potential Applications

• Extension of the method to emerging PFAS with expanded compound lists.
• Integration with automated sample preparation workflows to further increase throughput.
• Development of miniaturized or field-deployable LC/MS systems for on-site PFAS assessment.
• Continuous monitoring strategies leveraging high-speed data processing and expanded MRM libraries.

Conclusion

The Agilent Ultivo triple quadrupole LC/MS coupled with the 1290 Infinity II LC demonstrated exceptional performance for analyzing PFAS in drinking water according to EPA Methods 537.1 and 533. Shortened analysis times, low detection limits, robust recoveries, and minimal carryover underscore its suitability for high-throughput, compliance-driven testing where public health protection is paramount.

Reference

• Wang Z.; DeWitt J.C.; Higgins C.P.; Cousins I.T. A Never-Ending Story of Per- and Polyfluoroalkyl Substances (PFASs)? Environmental Science & Technology, 2017, 51 (5), 2508–2518.
• Agency for Toxic Substances and Disease Registry. Toxicological Profile for Per- and Polyfluoroalkyl Substances (PFAS), 2018.
• Hunt K.; et al. Extraction of Per/Polyfluoroalkyl Substances in Water Using Agilent Offline Solid Phase Extraction, Agilent Technologies Application Note 5994-0250EN, 2018.
• Hindle R.; et al. EPA Method 533 for Analysis of Per/Polyfluoroalkyl Substances in Drinking Water Using Agilent 6470 Triple Quadrupole LC/MS, Application Note 5994-1628EN, 2020.
• Anumol T.; et al. Recommended Plumbing Configurations for Reduction in Per/Polyfluoroalkyl Substance Background with Agilent 1260/1290 Infinity II LC Systems, Application Note 5991-7863EN, 2017.