Quantitative Analysis of Legacy and Emerging PFAS in Semiconductor Lubricant Using Agilent 6475 Triple Quadrupole LC/MS

Importance of the Topic

The presence of per- and polyfluoroalkyl substances (PFAS) in semiconductor lubricants poses significant environmental and health concerns due to their persistence, mobility, and bioaccumulation potential. Regulators worldwide are tightening restrictions on both legacy PFAS and emerging analogs, creating the need for highly sensitive, accurate analytical methods. Precise quantitation of trace PFAS supports compliance efforts, product quality control, and environmental stewardship in semiconductor manufacturing.

Objectives and Study Overview

This work aimed to establish a comprehensive workflow for the quantitative analysis of over 100 native and isotopically labeled PFAS in a high-oil-content semiconductor lubricant. The approach integrates organic solvent cleanup, solid-phase extraction (SPE) using a weak anion exchange cartridge, and triple-quadrupole liquid chromatography–mass spectrometry (LC/TQ) on Agilent platforms, targeting ultra-trace detection and robust method performance.

Methodology and Sample Preparation

The protocol comprises the following steps:

• Solvent Extraction: Three sequential extractions with methanol/dichloromethane and centrifugation to remove lipid content.
• Concentration: Near-drying under nitrogen and reconstitution in water.
• SPE Cleanup: Conditioning of Agilent Bond Elut PFAS WAX cartridges, sample loading under vacuum, washing, and elution with methanol and 0.1% ammonium hydroxide in methanol.
• Final Concentration: Evaporation and reconstitution in methanol/water (80:20 v/v) with isotope performance standards for LC/TQ injection.

Used Instrumentation

• Agilent 1290 Infinity II LC system with polyfluorinated compound–free HPLC kit.
• Agilent ZORBAX RRHD Eclipse Plus C18 column (2.1 × 100 mm, 1.8 μm).
• Agilent 6475 Triple Quadrupole LC/MS with Agilent Jet Stream ion source in negative ion mode.
• Agilent MassHunter LC/MS Acquisition and Quantitative Analysis software version 12.0.
• Gino/Grinder for sample agitation.
• Centrifuge for phase separation.
• Nitrogen evaporator for solvent removal.
• Polypropylene tubes and autosampler vials.

Main Results and Discussion

Calibration showed excellent linearity (R2 > 0.995) across at least three orders of magnitude with 1/x weighting (quadratic for FTSAs). Limits of quantitation (LOQs) were ≤ 0.1 μg/kg for 32 compounds and ≤ 1 μg/kg for 50 compounds, outperforming many regulatory thresholds by up to an order of magnitude. Method recovery and precision were evaluated using low (0.05–12.5 μg/kg) and high (0.2–50 μg/kg) matrix-spiked quality controls:

• Low-spike QC: 44 of 71 analytes achieved 70–130% recovery with ≤ 20% RSD.
• High-spike QC: 57 analytes met the same criteria, with nine additional compounds achieving recoveries of 50–61%.

Analysis of the unspiked lubricant revealed 15 native PFAS (e.g., PFOA, PFOS, PFBA, PFPeA) at sub-microgram-per-kilogram levels. Chromatographic overlays demonstrated consistent retention times and spike recoveries for PFOA and PFOS, confirming method precision.

Benefits and Practical Applications

The validated workflow delivers:

• High sensitivity and selectivity for PFAS in complex, oil-rich matrices.
• Compliance with multiple regulatory methods (EPA 1633, EPA 533, EPA 537.1, ASTM, ISO 21675, SW-846 8327).
• Rapid, reproducible sample preparation using off-the-shelf SPE cartridges.
• Support for quality control and environmental monitoring in semiconductor lubricants.

Future Trends and Opportunities

Potential developments include:

• Extension to other fluoropolymer-containing matrices (e.g., greases, coolants).
• Integration with high-resolution mass spectrometry for non-targeted PFAS screening.
• Automation and miniaturization of sample preparation to increase throughput.
• Method adaptation for emerging PFAS classes and next-generation alternatives.

Conclusion

A robust SPE–LC/TQ workflow on Agilent instruments has been demonstrated for the sensitive, accurate quantitation of legacy and emerging PFAS in semiconductor lubricants. The method achieves low LOQs, strong recoveries, and reproducibility, offering a ready-to-use solution for routine monitoring and regulatory compliance in complex oil-based matrices.

References

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