Analysis of Perfuorinated Alkyl Acids Specified in EPA M537 and Beyond Using LCMS-8045

Importance of the Topic

Perfluorinated alkyl acids (PFAAs) are persistent environmental contaminants found in water supplies worldwide. Their stability and bioaccumulation pose significant public health and ecological risks. Monitoring these compounds at trace levels is critical for regulatory compliance and safeguarding human health. The expansion of analytical methods to detect a broader range of PFAAs supports more comprehensive water quality assessments and informed decision-making.

Objectives and Study Overview

This study aimed to extend EPA Method 537 by including seven additional perfluorinated alkyl acids, achieving reliable quantitation of 24 target analytes in drinking water. Researchers evaluated method performance using Shimadzu’s LCMS-8045 coupled with solid phase extraction to meet stringent detection limits and recovery criteria.

Methodology and Instrumentation

Solid Phase Extraction (SPE) and LC-MS/MS were combined to isolate and quantify PFAAs from water samples.

• SPE Protocol: 250 mL water samples were spiked with surrogate standards, passed through Biotage ISOLUTE® SDVB cartridges, eluted with methanol, evaporated under nitrogen, and reconstituted in methanol–water (96:4).
• Chromatography: Separation on a Restek Raptor ARC-18 column (150 × 2.1 mm) using 20 mM ammonium acetate and methanol gradients.
• Mass Spectrometry: Shimadzu LCMS-8045 operated in multiple reaction monitoring (MRM) mode with optimized transitions via flow injection analysis.

Main Results and Discussion

Method Detection Limits (MDLs) ranged from 0.69 to 3.25 ppt for all 24 analytes, surpassing EPA 537 requirements.

• Calibration: Excellent linearity up to 100 ppb (R²≥0.992), with relative standard deviations below 13 %.
• Accuracy and Precision: Spiked recovery tests at 5 ppt and 60 ppt yielded recoveries between 79 % and 105 % and RSDs under 23 %.
• Surrogate Performance: Recoveries for internal standards averaged 106 %–109 % with RSDs below 14 %.

Benefits and Practical Applications

The validated method delivers rapid, sensitive quantitation of a wider spectrum of PFAAs in drinking water. Its robust performance supports:

• Routine monitoring by public health laboratories and environmental agencies.
• Regulatory compliance under evolving PFAS guidelines.
• Research on environmental fate and human exposure pathways.

Future Trends and Opportunities

Emerging nanoflow LC-MS technologies and high-resolution mass spectrometry offer potential for even lower detection thresholds and identification of novel PFAS species. Coupling with automated SPE and field-deployable samplers could further streamline monitoring efforts and enable real-time assessments.

Conclusion

The extended EPA 537 method using Shimadzu LCMS-8045 and Biotage ISOLUTE® cartridges demonstrates excellent sensitivity, accuracy, and precision for 24 perfluorinated alkyl acids. This approach meets regulatory requirements and enhances capacity for comprehensive water quality surveillance.

Reference

(1) EPA Method 537 Revision 1.1. Determination of Selected Perfluorinated Alkyl Acids in Drinking Water by SPE and LC-MS/MS. U.S. Environmental Protection Agency, Washington, D.C., 2009.
(2) ASTM D7979-16. Standard Test Method for Determination of Perfluorinated Compounds.