EU compliant routine quantitative dioxin, dioxin-like Compounds analysis by GC-MS/MS using an advanced electron ionization source

Importance of the Topic

The accurate and routine quantification of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and dioxin-like PCBs in food and feed is critical for consumer safety and regulatory compliance under European Union legislation. High sensitivity and robust analytical methods are essential to detect and confirm these contaminants at levels as low as one‐fifth of the maximum levels (MLs) established by EU regulations.

Objectives and Study Overview

This study evaluated the performance of two Thermo Scientific TSQ 9000 triple quadrupole GC-MS/MS systems equipped with an advanced electron ionization (AEI) source. Analyses were carried out in separate laboratories (UK and USA) by different operators using: solvent calibration standards, proficiency test (PT) samples, food and feed matrices, and certified reference materials (CRMs). The goal was to demonstrate EU-compliant sensitivity, accuracy, precision, and robustness across two sites.

Methodology and Instrumentation

The analytical workflow included:

• Sample Preparation: 2 g fat intake extraction by Twisselmann hot extraction or pressurized liquid extraction, followed by automated cleanup on a DEXTech™ Plus multi-layer column system.
• Instrumentation: TSQ 9000 GC-MS/MS with Advanced Electron Ionization source, TG-Dioxin capillary column, PTV injector, and Chromeleon™ CDS v7.2 for instrument control, data acquisition, and reporting.
• Quantification Strategy: Timed‐SRM acquisition with ^13C-labeled internal standards; calibration-based LOQ determination at 1/5th ML; separate fractions for non-ortho PCDD/Fs and mono-/di-ortho plus indicator PCBs.

Main Results and Discussion

Key findings from cross-laboratory validation and method performance assessments included:

• Chromatographic performance met all regulatory criteria, achieving baseline separation of tetra- and penta-chlorinated congeners.
• LOQ repeatability: ion ratio (IR) deviations remained within ±15% and response factor (RF) deviations <30% throughout sequences.
• WHO-PCDD/F-TEQ upper and lower bound values deviated by less than 6% from reference over 14 measurements, with <1.2% variation between bounds.
• Sensitivity achieved down to 0.15 pg/g WHO-PCDD/F-TEQ for a 2 g intake, satisfying the 1/5th ML requirement for most challenging matrices.
• Robustness demonstrated over ~161 injections spanning two weeks without maintenance (no source cleaning, liner changes, or column trimming), with stable sensitivity and repeatability.
• Cross-lab agreement: analysis of CRM WMF-01 in Beijing yielded congener concentrations within specified tolerances and calibration RF %RSD <6% over four orders of magnitude.

Benefits and Practical Applications

• Regulatory Compliance: Meets EU requirements for confirmatory analysis of PCDD/Fs and dioxin-like PCBs in food and feed.
• High Throughput: Extended runtimes with minimal maintenance maximize sample throughput.
• Automated Workflows: Chromeleon CDS with integrated eWorkflows ensures error-free setup, processing, and reporting without external spreadsheets.
• Quality Assurance: Calibration-based LOQ monitoring and real-time IR/RF checks guarantee ongoing method performance.

Future Trends and Potential Applications

• Integration of high-resolution mass spectrometry and advanced ionization sources to lower detection limits further.
• Expansion toward multi-residue workflows combining dioxins with emerging organic contaminants.
• Enhanced automation of sample prep and AI-driven data processing to reduce turnaround times.
• Standardized, harmonized protocols across global reference laboratories for consistent regulatory testing.

Conclusion

The TSQ 9000 GC-MS/MS system with the AEI source, combined with robust sample preparation and Chromeleon CDS, provides a high-sensitivity, reliable, and maintenance-free solution for routine EU-compliant analysis of PCDD/Fs and PCBs in food and feed. Its proven cross-laboratory performance and extended uptime make it ideal for high-throughput regulatory testing.

References

1. European Commission, Commission Regulation (EU) 2017/644, Official Journal of the European Union L 92 9-34, 2017.
2. European Commission, Commission Regulation (EU) 2017/771, Official Journal of the European Union L 115 22-42, 2017.
3. Thermo Fisher Scientific Application Note AN-10590: Low level quantification of PCDD/Fs in animal feed using the TSQ 9000 triple quadrupole GC-MS/MS system with AEI source.
4. Guidance Document on the Estimation of LOD and LOQ for Measurements in the Field of Contaminants in Feed and Food, European Commission Joint Research Centre.
5. Directive 2002/32/EC of the European Parliament and of the Council of 7 May 2002 on undesirable substances in animal feed, as amended, Official Journal of the European Communities L 140 10-21, 2002.