Determination of Polychlorinated Biphenyl Congeners in Foodstuffs and Animal Feed using a Triple Quadrupole GC-MS/MS Instrument

Meaning of the Topic

Polychlorinated biphenyls (PCBs) are persistent organic pollutants with known carcinogenic and endocrine-disrupting effects. Their accumulation in animal tissues poses a risk to human health through food consumption. Regulatory bodies in the EU and the US mandate reliable quantification of dioxin-like and non-dioxin-like PCBs in foodstuffs and feed to enforce safety limits.

Aims and Overview

This study presents a sensitive, reproducible GC-MS/MS screening method for:

• 12 dioxin-like PCB congeners (dl-PCBs)
• 6 non-dioxin-like indicator PCBs (ndl-PCBs)

The method is benchmarked against isotope-dilution GC-HRMS to demonstrate compliance with current EU legislation and to assess performance for routine QC applications.

Methodology and Instrumentation

Sample Preparation:

• Fat extraction by Soxhlet or accelerated solvent extraction with toluene/acetone or hexane
• Cleanup using sulfuric-acid silica, Florisil and active carbon columns
• Fractionation into mono-ortho, non-ortho PCB and PCDD/F fractions
• Addition of 13C-labelled internal standards at extraction start

GC-MS/MS Analysis:

• GC: Agilent 7890 with 50 m × 0.22 mm ID, 0.25 µm HT-8 column
• Autosampler: Agilent 7693A, 2 µL cold splitless injection
• MS: Agilent 7000 triple quadrupole, electron ionization, MRM mode
• Run times: 50 min for mono-ortho/ndl-PCBs; 33 min for non-ortho PCBs
• Calibration: 7-point ISTD curves (0.05–50 pg/µL for mono-ortho; 0.10–10 pg/µL for non-ortho)

Main Results and Discussion

Linearity and Sensitivity:

• All congeners achieved R2 > 0.998
• Limits of detection at low pg TEQ/g levels

Comparative Performance:

• 80 samples analyzed by both GC-HRMS and GC-MS/MS
• dl-PCB results within ±10 % for levels >1 pg TEQ/g
• ndl-PCB sum within ±10 % for 0.5–10 ng/g samples
• Minor losses in accuracy (< 15 % difference) at very low TEQ (<0.1 pg TEQ/g)

Benefits and Practical Applications

The triple quadrupole GC-MS/MS approach offers:

• Cost-effective alternative to high-resolution systems
• High reproducibility and throughput for routine screening
• Compliance with EU and US regulatory limits for PCBs in food and feed

Future Trends and Opportunities

Continuation of this work may include:

• Method extension to additional persistent organic pollutants
• Automation of sample cleanup workflows
• Integration with high-throughput labs for large-scale monitoring

Conclusion

The Agilent 7000 GC-MS/MS method delivers robust, linear, and sensitive detection of both dl- and ndl-PCBs in foodstuffs and animal feed. Its performance closely matches GC-HRMS, validating its use for routine regulatory screening.

Used Instrumentation

• Agilent 7890 gas chromatograph
• Agilent 7693A autosampler with CO2-cooled multimode inlet
• HT-8 capillary column (50 m × 0.22 mm ID, 0.25 µm)
• Agilent 7000 triple quadrupole mass spectrometer

References

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 of dioxins and dl-PCBs in food
3. C. Sandy, Determination of PCDD and PCDF in Foodstuffs and Animal Feed using Agilent 7000 GC/MS, Agilent Technologies publication 5990-6594EN (2010)
4. Commission Regulation (EC) No 1881/2006 setting maximum levels for contaminants in foodstuffs
5. Commission Regulation (EC) No 152/2009 Annex V on official control of feed
6. Directive 2002/32/EC on undesirable substances in animal feed