Analysis of PFAS Specified in EPA Method 537 and Beyond using Shimadzu UFMS™

Significance of the Topic

Per- and polyfluoroalkyl substances are persistent environmental contaminants widely used in coatings, fire retardants and food packaging for their water- and oil-repellent properties
They resist degradation and bioaccumulate, leading to global concerns over drinking water contamination and adverse health effects
Regulatory agencies such as the US EPA have set advisory limits for PFOS and PFOA, driving the need for sensitive, reliable analytical methods

Study Objectives and Overview

This study evaluated Shimadzu’s Ultra-fast Mass Spectrometry (UFMS™) performance in alignment with EPA Method 537 for 14 regulated PFAS and an extended panel of seven additional compounds
Two triple-quadrupole LCMS systems (LCMS-8045 and LCMS-8050) were compared for sensitivity, linearity, accuracy and precision in drinking water analysis

Instrument Used

• Nexera™-X2 UHPLC system with Shim-pack Velox SP-C18 analytical column
• Shimadzu LCMS-8045 and LCMS-8050 UFMS platforms featuring rapid polarity switching and high MRM acquisition speed
• Solvent delay column to trap PFAS background from LC solvents
• Biotage-ISOLUTE SDVB SPE cartridges for sample extraction

Methodology

Sample Preparation and SPE

• 250 mL drinking water samples fortified with surrogates and passed through SDVB SPE cartridges
• Elution with methanol, evaporation under nitrogen, reconstitution in methanol : water

Calibration and Internal Standards

• Ten-point calibration from 1.25 to 100 ng/mL using 21 target PFAS, 3 internal standards and 3 surrogates
• Injection volume of 1 µL, equivalent to 5 ng/L method range after concentration

Chromatographic and MS Conditions

• Mobile phase of 20 mM ammonium acetate and methanol at 0.25 mL/min, 35 min run time
• ESI source with optimized temperatures and gas flows
• MRM transitions for quantification and confirmation of 27 PFAS

Quality Control

• Continuing calibration checks at low, mid and high levels over two weeks
• Method Detection Limit study at 5 ng/L with nine replicates
• Accuracy and precision evaluated at 60 ng/L with seven replicates

Main Results and Discussion

Chromatographic Separation

• Clear resolution of linear and branched PFHxS and PFOS isomers on Velox SP-C18
• Effective separation of expanded PFAS panel within the run time

Linearity and Calibration

• All PFAS calibration curves exhibited R2 > 0.99
• Continuing calibration checks showed recoveries within 70 – 130% and RSDs under 15%

Detection Limits

• LCMS-8050 achieved MDLs of 0.7 – 1.7 ng/L
• LCMS-8045 recorded MDLs of 0.7 – 3.3 ng/L

Accuracy and Precision

• Recoveries of 21 – 109% for target PFAS and surrogates, within EPA criteria
• Precision RSDs generally below 15%

System Performance Comparison

• LCMS-8050 demonstrated superior signal-to-noise and lower MDLs
• Both systems met EPA 537 requirements with a reduced injection volume, enhancing robustness

Benefits and Practical Applications

• High sensitivity and rapid polarity switching enable reliable quantitation of regulated and emerging PFAS
• Reduced solvent consumption and lower injection volumes extend column lifetime and lower operational costs
• Single UFMS platform can run multiple regulatory methods, simplifying laboratory workflows

Future Trends and Potential Applications

• Expansion of PFAS target lists as new precursors and degradation products are regulated
• Integration with high-resolution MS for non-target screening
• Automation and online SPE coupling for higher throughput and on-site monitoring
• Adoption of UFMS in environmental, industrial and QA/QC laboratories for routine PFAS surveillance

Conclusion

Shimadzu UFMS systems (LCMS-8045 and LCMS-8050) provide sensitive, accurate and robust analysis of 21 PFAS compounds in drinking water, fulfilling and exceeding EPA Method 537 requirements
The LCMS-8050 in particular offers enhanced detection limits and signal-to-noise performance, enabling laboratories to efficiently monitor both regulated and emerging PFAS

References

1. U S EPA Method 537 Determination of Selected Perfluorinated Alkyl Acids in Drinking Water by SPE and LC/MS/MS 2009
2. ASTM D7979-17 Standard Test Method for Determination of Perfluorinated Compounds in Water, Sludge, Influent, Effluent and Wastewater by LC/MS/MS 2017