Determination of Dioxin-Like and Non-Dioxin-Like Polychlorinated Biphenyl Congeners in Foodstuffs and Animal Feed Using the Agilent 7000 Triple Quadrupole GC/MS System

Significance of the Topic

Polychlorinated biphenyls (PCBs) are persistent organic pollutants linked to cancer, endocrine disruption and reproductive disorders. Despite their ban in the late 20th century, PCBs remain in the environment and bioaccumulate in animal tissues, entering the human food chain. Regulatory bodies in the EU and US set strict limits for dioxin-like PCBs (dl-PCBs) and non-dioxin-like PCBs (ndl-PCBs) in foodstuffs and animal feed, expressed as Toxic Equivalent (TEQ) using WHO-assigned Toxic Equivalency Factors (TEFs). Reliable, sensitive analytical methods are essential for compliance and risk assessment.

Objectives and Study Overview

This study presents two analytical methods using the Agilent 7000 Triple Quadrupole GC/MS system for simultaneous quantification of 12 dl-PCB congeners (eight mono-ortho and four non-ortho) and six indicator ndl-PCB congeners in foodstuffs and animal feed. The goals were to achieve linear response over regulatory concentration ranges, quantify dl-PCBs down to pg TEQ/g levels and ndl-PCBs below 1 ng/g, and compare results with a high-resolution GC-MS reference method.

Applied Methodology and Instrumentation

Sample Preparation

• Extraction of fat matrix using Soxhlet, Accelerated Solvent Extraction (ASE) or solvent mixtures (toluene/acetone or hexane).
• Sequential cleanup on sulfuric acid-coated silica, florisil and active carbon columns to fractionate mono-ortho/indicator PCBs, non-ortho PCBs and PCDD/Fs.
• Spiking with 13C-labelled internal standards, concentration under nitrogen, reconstitution in toluene.

Instrument Configuration

• Gas chromatograph: Agilent 7890 equipped with Multimode Inlet (CO₂-cooled) and HT-8 column (50 m × 0.22 mm, 0.25 µm).
• Mass spectrometer: Agilent 7000 Triple Quadrupole GC/MS in MS/MS-EI MRM mode.
• Liquid autosampler: Agilent 7693A at 5 °C, 2 µL cold splitless injection.
• MS settings: Electron energy –78 eV, ion source 280 °C, collision gases N₂ and He, unit MS1 resolution, wide MS2.

Main Results and Discussion

MRM chromatograms confirmed clear separation of all 18 PCB congeners within 33–50 min runs. Seven-point internal standard calibration achieved excellent linearity (R² > 0.998) across 0.05–50 pg/µL (dl-PCBs) and 0.1–10 pg/µL (ndl-PCBs). In a comparative study of 80 food/feed samples analyzed by both GC-HRMS and GC/TQMS:

• Total dl-PCB (TEQWHO98) levels >1 pg TEQ/g agreed within ±10%.
• Levels between 0.1–1 pg TEQ/g agreed within ±15%.
• Total ndl-PCB sums (0.5–10 ng/g) agreed within ±10%.

Lower-level samples showed increased variability but still demonstrated method suitability for regulatory screening.

Benefits and Practical Applications

The Agilent 7000 Triple Quadrupole GC/MS delivers:

• High sensitivity for dl-PCBs at pg TEQ/g and ndl-PCBs at low ng/g.
• Robust, reproducible quantitation meeting EU screening requirements.
• Faster throughput compared to high-resolution MS while maintaining compliance accuracy.

This makes it ideal for routine monitoring in QA/QC laboratories, food safety authorities and industrial analytics.

Future Trends and Potential Applications

Advances likely include further automation of sample prep, higher-throughput GC-MS/MS workflows, integration of novel ionization techniques for broader analyte panels and continued harmonization of TEF values and regulatory standards. Coupling with data-processing software and real-time monitoring may enhance responsiveness to emerging contaminants.

Conclusion

The Agilent 7000 Triple Quadrupole GC/MS system provides a validated, sensitive and linear approach for simultaneous determination of dl- and ndl-PCB congeners in foodstuffs and animal feed. Comparative results with GC-HRMS confirm its suitability for regulatory screening, offering a cost-effective, high-throughput alternative without compromising accuracy.

Reference

1. EPA Method 1668, Revision A: Chlorinated Biphenyl Congeners in Water, Soil, Sediment and Tissue by HRGC/HRMS.
2. Commission Regulation (EC) No 1883/2006 on sampling and analysis for dioxins and dl-PCBs in foodstuffs.
3. C. Sandy, Determination of PCDD/F in Foodstuffs and Feed Using Agilent 7000 Triple Quadrupole GC/MS, Agilent Technologies 5990-6594EN (2010).
4. Commission Regulation (EC) No 1881/2006 Setting maximum levels for certain contaminants in foodstuffs.
5. Commission Regulation (EC) No 152/2009 Annex V on methods of sampling and analysis for feed.
6. Directive 2002/32/EC on undesirable substances in animal feed.