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

Importance of the Topic

Effective monitoring of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and dioxin-like PCBs in food and feed is critical for consumer safety and regulatory compliance across the European Union. The ability to deliver accurate, sensitive, and robust quantification at levels well below legal limits supports risk assessment, quality control, and enforcement of maximum levels (MLs) and action levels (ALs) established by EU regulations.

Objectives and Study Overview

The primary aim of this study was to assess the routine-grade performance of a triple quadrupole GC-MS/MS system equipped with an Advanced Electron Ionization (AEI) source. Two Thermo Scientific™ TSQ™ 9000 instruments located in separate laboratories (UK and USA) were evaluated. Key goals included:

• Validation of calibration-based limits of quantitation (LOQs) in accordance with European Union Reference Laboratory (EURL) guidance.
• Comparison of performance using solvent standards, proficiency test (PT) samples, mixed matrix extracts, and certified reference materials (CRMs).
• Verification of system robustness and minimal maintenance requirements over extended sequences.

Methodology and Instrumentation

Sample Preparation and Cleanup:

• Sample intake: nominal 2 g fat per sample (Twisselmann hot extraction or pressurized liquid extraction).
• Automated cleanup on DEXTech™ Plus multi-layer columns (acidic silica, alumina, carbon).
• Fractionation into non-ortho PCDD/Fs & PCBs and mono-/di-ortho PCBs & indicator PCBs.

Instrumental Setup:

• Gas chromatograph: TG-Dioxin capillary column optimized for PCDD/F and PCB separations.
• Mass spectrometer: TSQ 9000 triple quadrupole GC-MS/MS with Advanced Electron Ionization (AEI) source.
• Data system: Thermo Scientific™ Chromeleon™ CDS software (version 7.2) for full control, SRM acquisition, and automated compliance reporting.

Main Results and Discussion

LOQ Determination and Repeatability:

• Calibration-based LOQs achieved reported upper-bound WHO-PCDD/F-TEQ values as low as 0.15 pg/g (2 g sample), meeting 1/5th ML requirements.
• Inter-laboratory reproducibility: upper- and lower-bound TEQ deviations remained below 1.2% across 14 measurements.
• Signal stability: RF %RSD <6% over four orders of magnitude for key congeners.

Sensitivity and Accuracy:

• Analysis of CRM (WMF-01) yielded results within specified tolerances for all PCDD/F congeners versus reference values.
• Calibration linearity maintained over more than four orders of magnitude, enabling reliable quantification from trace to elevated levels.

System Robustness:

• Extended sequence of 161 injections over two weeks with no source cleaning, liner changes, tuning, or column trimming.
• Sustained sensitivity and consistent ion ratio (IR) and response factor (RF) performance in highly complex matrix injections.

Benefits and Practical Applications

The TSQ 9000 AEI system delivers several tangible advantages for routine dioxin and PCB analysis in food and feed laboratories:

• Regulatory compliance: meets EU Regulations 644/2017 and 771/2017 for ML and AL monitoring.
• High throughput: automated workflows in Chromeleon CDS eliminate manual data handling and ensure SOP-compliant analyses.
• Reduced downtime: demonstrated two-week continuous operation without maintenance.
• Versatility: suitable for proficiency tests, quality control, and confirmatory analyses across diverse food/feed matrices.

Future Trends and Possibilities

Advancements likely to further enhance routine dioxin analysis include:

• Integration of real-time data analytics and machine-learning algorithms for automated peak identification and anomaly detection.
• Miniaturization of sample preparation and on-line cleanup to reduce solvent use and increase throughput.
• Development of multi-analyte methods combining dioxins with other persistent organic pollutants in a single run.
• Cloud-based data management to facilitate inter-laboratory harmonization and remote auditing.

Conclusion

Comprehensive evaluation across two laboratories confirms that the TSQ 9000 GC-MS/MS system with AEI source and Chromeleon CDS software provides routine-grade sensitivity, accuracy, and robustness for quantitative and confirmatory analysis of PCDD/Fs, dioxin-like PCBs, and indicator PCBs in food and feed. The method fulfills stringent EU regulatory requirements while minimizing operator intervention and maintenance.

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. Low level quantification of PCDD/Fs in animal feed using the TSQ 9000 triple quadrupole GC-MS/MS system with AEI source. Application Note AN-10590.
4. European Union Reference Laboratory. Guidance Document on the Estimation of LOD and LOQ for Measurements in the Field of Contaminants in Feed and Food.
5. Directive 2002/32/EC of the European Parliament and of the Council on undesirable substances in animal feed, Official Journal of the European Communities, L 140:10–21 (2002).