Improved detection capabilities for polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) using GC Orbitrap MS

Significance of the topic

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) are highly toxic contaminants that require ultra-trace detection in food and feed to protect public health and meet regulatory limits. Analytical methods must combine exceptional sensitivity, selectivity and long-term robustness to quantify toxic equivalents (WHO-PCDD/F-TEQ) at part-per-trillion to sub-ppt levels while meeting stringent EU performance criteria for ion ratios, calibration behavior and method limits of quantification (LOQs).

Study objectives and overview

This work evaluates the analytical capability of gas chromatography coupled to a high-resolution accurate-mass Orbitrap mass spectrometer (Orbitrap Exploris GC S) equipped with the NeverVent Advanced Electron Ionization (NVAEI) source for determination of PCDD/Fs in food and feed. Key aims were to demonstrate compliance with EU analytical criteria, to reach quantitation at/below regulatory limits, to compare results with GC-HRMS magnetic sector measurements, and to assess long-run stability of trace-level responses.

Methods and sample preparation

Samples included representative food and feed matrices (butter, laying hen fat, fish oil, edible flowers, dill tips). Sample preparation and cleanup approaches were:

• Accelerated solvent extraction (ASE) with sulfuric acid treatment for matrix removal, or automated multi-column solid phase extraction for cleanup.
• Large-volume injection GC analysis of purified extracts.
• Isotopic dilution quantification using 13C-labeled internal standards spiked into purified extracts.

Instrumentation used

Key instrumental components and configurations reported:

• Thermo Scientific Orbitrap Exploris GC S high-resolution accurate-mass (HRAM) mass spectrometer.
• NeverVent Advanced Electron Ionization (NVAEI) ion source to enhance sensitivity and stability at trace levels.
• Gas chromatograph capable of large-volume injections compatible with routine dioxin analysis.

Main results and discussion

The Orbitrap Exploris GC S with the NVAEI source delivered performance that met or exceeded regulatory requirements:

• Sensitivity: Accurate quantitation of 2378-TCDD down to 2 fg/µL (10 fg on-column) was achieved while meeting ion-ratio (±15%) and calibration response (±25%) criteria.
• Stability: The 2 fg/µL TCDD response remained stable across a 185-injection sequence of food/feed extract, demonstrating robust long-run performance of the NVAEI source at trace-level detection.
• Mass resolution: Measured resolving power exceeded the regulatory requirement (R ≈ 23,046 FWHM equivalent; observed R up to ~39,700 at m/z ~455 for OCDD), providing clear peak separation and mass accuracy to support selective identification and reliable ion-ratio assessment.
• Method LOQs: Sample LOQs (WHO-PCDD/F-TEQ) were well below 1/5 of the maximum levels (ML) required by EU Regulation, examples include butter 0.229 pg/g (ML 2.5 pg/g), laying hen fat 0.232 pg/g (ML 2.5 pg/g), fish oil 0.232 pg/g (ML 1.75 pg/g), edible flowers 0.062 pg/g (ML 0.75 pg/g), and dill tips 0.061 pg/g (ML 0.75 pg/g).
• Comparative performance: Good agreement was observed between quantitative results obtained using the Orbitrap Exploris GC S and a GC-HRMS magnetic sector instrument at and below regulatory limits, indicating the Orbitrap platform can produce results comparable to established high-resolution systems.

Benefits and practical applications

The evaluated Orbitrap Exploris GC S workflow offers several practical advantages for routine dioxin monitoring labs:

• Enhanced sensitivity enabling reliable quantitation at femtogram levels on-column and LOQs comfortably below 1/5 ML for diverse matrices.
• High mass resolution and mass accuracy that improve selectivity, minimize false positives, and support compliance with ion-ratio requirements.
• Operational robustness demonstrated by stable responses over extended injection sequences, reducing re-analysis and downtime.
• Compatibility with existing sample-prep strategies (ASE, SPE) and isotopic-dilution quantification enables integration into established laboratory workflows for food/feed control and research.

Future trends and applications

Potential directions and broader uses of HRAM Orbitrap GC in dioxin and persistent organic pollutant (POP) analysis include:

• Expanded adoption of HRAM Orbitrap instruments as alternatives to magnetic-sector HRMS for regulated dioxin analysis, driven by comparable accuracy and improved operational flexibility.
• Further optimization of automated cleanup and large-volume injection strategies to increase throughput while maintaining ultra-trace LOQs across complex matrices.
• Application of the platform to multi-class POP screening (dioxin-like PCBs, legacy pesticides, brominated flame retardants) leveraging accurate-mass full-scan data for retrospective analyses.
• Continued improvements in ion source design and data-processing workflows to enhance sensitivity, reduce matrix effects, and standardize routine compliance testing.

Conclusions

The Orbitrap Exploris GC S coupled with the NeverVent AEI ion source achieved accurate, regulatory-compliant quantitation of PCDD/Fs down to 2 fg/µL (10 fg on-column) and produced method LOQs below one-fifth of EU maximum levels across several food and feed matrices. Performance matched GC-HRMS magnetic sector results at regulatory limits and demonstrated robust stability over long injection sequences, supporting the Orbitrap HRAM platform as a viable, high-performance alternative for routine dioxin monitoring in food and feed laboratories.

References

1. Warner N, Krätschmer K, Roberts D, Kutscher D. Polychlorinated dibenzo-p-dioxins/furan analysis in food and feed at regulatory limits using the Orbitrap Exploris GC S mass spectrometer. Thermo Scientific application note AN004451.
2. Commission Regulation (EU) 2017/664. Laying down methods of sampling and analysis for the control of levels of dioxins, dioxin-like PCBs and non-dioxin-like PCBs in certain foodstuffs and repealing Regulation (EU) No. 589/2014.