Comprehensive PFAS Analysis Using Diverse LC Column Types

Significance of the Topic

PFAS are persistent environmental contaminants with diverse industrial and consumer applications. Their stability and widespread occurrence in water, soil, and biota pose health risks and regulatory challenges. Analytical methods capable of detecting both long-chain and ultrashort-chain PFAS in complex matrices are essential for environmental monitoring, food safety, and regulatory compliance.

Objectives and Study Overview

This study evaluates the performance of multiple reversed-phase and ion-exchange liquid chromatography columns for comprehensive PFAS profiling. Key goals include:

• Assessing retention and separation of legacy long-chain, ultrashort-chain, and emerging PFAS derivatives.
• Comparing standard C18 with polar-embedded alkyl (Ultra IBD) and mixed-mode anion exchange/HILIC (Polar X) phases.
• Developing robust workflows for various sample types, including water, plasma, and serum.

Methodology and Instrumentation

A suite of LC-MS/MS platforms was employed to optimize PFAS detection across a broad polarity range:

• Instrumentation Used
  • Waters TQ-S triple quadrupole MS coupled to UPLC systems
  • Columns:
    • Raptor C18 (50×2.1 mm, 2.7 μm)
    • Ultra Inert IBD (100×2.1 mm, 3.0 μm)
    • Raptor Polar X (50×2.1 mm, 2.7 μm)
  • Mobile phases: ammonium acetate or formate buffers with formic/acetic acid modifiers, acetonitrile and methanol blends
  • Injection volumes ranged 10–50 μL; column temperatures 40 °C

Main Results and Discussion

• C18 Phase: Provided sharp peaks for C6–C14 PFAS but inadequate retention and peak shape for ultrashort-chain analytes, especially in complex matrices.
• Ultra IBD Phase: Polar-embedded alkyl chemistry extended retention of C2–C4 PFAS under reversed-phase conditions, reducing matrix effects in plasma and milk.
• Polar X Phase: Mixed-mode HILIC and anion-exchange interactions delivered strong retention of highly acidic and ultrashort PFAS. Isocratic methods achieved baseline separation in under 8 minutes.
• Performance Metrics: Limits of detection often < 0.01 ng/mL; recoveries ranged 86–107 %; precision (RSD) < 11 % across water and biological samples. Correlation coefficients > 0.995 for most analytes.

Benefits and Practical Applications

• Enables simultaneous detection of a wide PFAS spectrum without chemical derivatization.
• Reduced sample preparation complexity by direct injection or simple dilution for aqueous samples.
• Improved robustness in dirty and high-salt matrices such as wastewater, plasma, and serum.
• Short run times (8–12 minutes) support high throughput in routine monitoring laboratories.

Future Trends and Applications

• Integration of supercritical fluid chromatography to further shorten analysis times and expand PFAS coverage.
• Adoption of high-resolution mass spectrometry for non-targeted screening of novel PFAS structures.
• Green analytical chemistry approaches to minimize solvent consumption and reduce environmental footprint.
• Automation of sample preparation through inline SPE and microfluidic platforms for increased reproducibility.

Conclusion

Comprehensive PFAS analysis requires tailored column chemistries to address diverse analyte properties and sample complexities. While conventional C18 remains effective for long-chain PFAS, polar-embedded and mixed-mode columns significantly enhance detection of ultrashort-chain and highly acidic compounds. The combination of optimized mobile phases and robust LC-MS/MS conditions delivers reliable, high-throughput workflows suitable for regulatory compliance and research applications.