Faster Than the Speed of Life: A Rapid Screening Method for Select PFAS Compounds in Serum by RapidFire-MS

Significance of the Topic

Per- and polyfluoroalkyl substances (PFAS) are persistent synthetic compounds used in numerous industrial and consumer products. Their environmental stability and potential health effects have driven the need for sensitive, high-throughput screening methods in biological matrices such as human serum.

Objectives and Study Overview

This work aimed to develop and validate a rapid screening workflow for selected PFAS in serum. Key goals included minimizing sample preparation time, achieving low limits of quantitation (LOQs), and ensuring robust performance on a RapidFire-MS platform.

Experimental Methodology and Instrumentation

Sample preparation comprised two approaches: simple protein precipitation and protein precipitation combined with Captiva EMR-Lipid cleanup. Each 100 µL serum aliquot was spiked with native and extracted isotopic standards, vortexed, then crashed with acidified acetonitrile. For lipid removal, the supernatant passed through a pre-rinsed Captiva EMR-Lipid cartridge under positive pressure.

• Instrumentation Used
  • Agilent RapidFire 400 front-end autosampler
  • Agilent 6495D triple quadrupole mass spectrometer with JetStream ESI
  • RapidFire cartridges (C18 and custom mixed-mode C18/anion exchange)

Main Results and Discussion

Method optimization identified the custom mixed-mode cartridge as superior for retaining short-chain PFAS compared to conventional C18. The total RapidFire-MS cycle time was approximately 12.5 seconds per sample. LOQs for most analytes were 0.1 ppb or lower, with calibration ranges spanning 0.01–10 ppb. Dilution improved signal for protein-only samples but was unnecessary when lipid cleanup was applied, as EMR-Lipid effectively removed matrix interferences.

Advantages and Practical Applications

The developed workflow offers:

• High throughput: ~300 injections per hour
• High sensitivity: LOQs ≤0.1 ppb for key PFAS
• Minimal system background and matrix effects with EMR-Lipid cleanup

Future Trends and Applications

Future efforts may expand the PFAS analyte panel, integrate high-resolution MS for non-targeted screening, and automate sample handling for routine clinical and environmental biomonitoring studies.

Conclusion

RapidFire-MS combined with optimized sample cleanup and custom mixed-mode cartridges delivers a fast, sensitive, and reliable method for PFAS screening in serum. This approach can support large-scale biomonitoring and exposure assessment.

Reference

Zhao, L., and Juck, M. Protein Precipitation for Biological Fluid Samples Using Agilent Captiva EMR-Lipid 96-Well Plates; Agilent Application Note 5991-9222EN, 2018.