Implementing new GC-MS and LC-MS technologies to stay ahead with your food safety analysis from pesticides to PFAS and microplastics

Significance of PFAS Analysis

Per- and polyfluorinated alkyl substances (PFAS) represent a large group of persistent anthropogenic contaminants with unique physicochemical properties that have led to widespread environmental distribution and bioaccumulation. In food safety, the trace-level occurrence of PFAS in products such as meat, dairy and produce poses potential health risks. Reliable analytical methods capable of quantifying and confirming a broad spectrum of PFAS are essential for regulatory compliance, consumer protection and retrospective screening for emerging compounds.

Aims and Study Overview

This work demonstrates an advanced LC-MS workflow for sensitive quantitation and confident confirmation of PFAS in complex food matrices. The objectives were to develop and validate a QuEChERS-based extraction in pork muscle, couple it with high-resolution accurate mass (HRAM) analysis on an Orbitrap Exploris 120 mass spectrometer operating in full-scan data-independent acquisition (FS-DIA) mode, and to illustrate the integration of proprietary spectral libraries using the myLibrary Enterprise platform for enhanced compound identification.

Methodology and Used Instrumentation

• Sample Preparation: Following a modified USFDA C-010.01 protocol, 5 g ground pork was spiked with isotopically labeled PFAS, extracted with acetonitrile/water/formic acid, cleaned by dSPE (MgSO₄, PSA, GCB) and transferred into PFAS-free polypropylene vials.
• LC Setup: Thermo Scientific Vanquish Flex UHPLC with sandwich-injection programming, trap column (Hypersil Gold C18, 50 × 4.6 mm, 1.9 µm) and analytical column (Accucore C18, 100 × 2.1 mm, 2.6 µm); gradient elution with 5 mM ammonium acetate in water and methanol; run time 19 min; column 40 °C, 400 µL/min flow.
• Mass Spectrometry: Thermo Scientific Orbitrap Exploris 120 in negative ESI mode; full-scan m/z 100–1000 at 60,000 resolution; DIA MS2 at 15,000 resolution with five stepped NCE windows; spray voltage 1 kV; capillary 220 °C, vaporizer 450 °C.
• Spectral Library Management: myLibrary Enterprise on AWS for proprietary library creation, curation and export to Thermo Scientific mzVault; used in TraceFinder software for fragment matching and spectral scoring.

Main Results and Discussion

• Calibration: 34 target PFAS plus 23 labeled standards over 5–5000 ppt in solvent; linearity R² 0.9516–0.9993; %RSD ≤ 7 %.
• Recovery and Precision: In pork muscle at 25–500 pg/g spikes, most recoveries ranged 80–120 % with %RSD < 20 %. Longer-chain PFAS showed reduced recovery at lower levels, likely due to GCB adsorption. Background contamination of PFBA and PFOA was detected in blanks.
• Limits of Quantitation: Final extract LOQs for most PFAS were ≤ 50 ppt (equivalent to 16.7 pg/g in matrix).
• Confirmation: Native PFAS ions detected at < 5 ppm mass error with S/N ≥ 3 and at least one fragment match; library search scores provided additional confidence in identification at low ppt levels.

Benefits and Practical Applications

• High-Resolution MS enables simultaneous targeted quantitation and untargeted retrospective PFAS screening without prior selection of analytes.
• FS-DIA acquisition overcomes matrix interferences common in complex biological extracts.
• myLibrary Enterprise provides secure, collaborative spectral libraries that streamline confirmation workflows and support multi-site consistency.
• The approach is adaptable to other food matrices and expanding PFAS lists, offering a fit-for-purpose method for regulatory, QA/QC and research laboratories.

Future Trends and Opportunities

• Extension to diverse matrices (tissues, dairy, produce, water) and to emerging PFAS classes as novel compounds are discovered.
• Integration of GC-MS for volatile PFAS and multi-class screening, including pesticides and microplastics markers, in a unified workflow.
• Enhanced non-targeted data mining using HRAM archives for proactive monitoring of legacy and emerging contaminants.
• Automation and AI-driven spectral curation to accelerate library building and ensure data quality in high-throughput environments.

Conclusion

The combination of a streamlined QuEChERS extraction, Vanquish Flex UHPLC, and Orbitrap Exploris 120 in FS-DIA mode achieved sensitive quantitation and robust confirmation of 34 PFAS in pork muscle with LOQs below 50 ppt. The deployment of myLibrary Enterprise facilitated high-confidence spectral matching, enabling both targeted and retrospective screening. This workflow demonstrates a powerful platform for comprehensive PFAS analysis in food safety laboratories and sets the stage for future expansion into broader classes of contaminants.