Routine, regulatory analysis of dioxins and dioxin-like compounds in food and feed samples

Importance of the Topic

The occurrence of polychlorinated dibenzo-p-dioxins (PCDD/Fs) and dioxin-like polychlorinated biphenyls (PCBs) in food and feed represents a significant public health concern due to their high toxicity, persistence, and bioaccumulation in lipid tissues. Regulatory bodies worldwide mandate strict maximum levels and routine monitoring to minimize human exposure, which largely occurs via dietary intake of meat, dairy, fish, and eggs.

Study Objectives and Overview

This study evaluates the Thermo Scientific TSQ 9000 triple quadrupole GC-MS/MS system, equipped with an advanced electron ionization (AEI) source and controlled through the Chromeleon 7.2 chromatography data system (CDS), for routine, regulatory-compliant quantification of 17 toxic PCDD/F congeners and 18 dioxin-like and indicator PCBs in a broad range of food and feed matrices. Analyses were performed in two laboratories (UK and USA) by different operators to assess method robustness and reproducibility.

Methodology and Instrumentation

Samples included proficiency test materials, certified reference materials, commercial foodstuffs, and feed products, with nominal fat-based sample intakes typically of 2 g. Extraction employed Twisselmann hot extraction or pressurized liquid extraction followed by automated multi-layer column cleanup on a DEXTech Plus system. Two GC-MS/MS methods targeted (1) non-ortho PCBs and PCDD/Fs and (2) mono-ortho, di-ortho, and indicator PCBs.

Instrumental Setup

• Thermo Scientific TRACE 1310 Gas Chromatograph with 60 m × 0.25 mm × 0.25 µm TG-Dioxin capillary column (run time ~44.7 min).
• Thermo Scientific TSQ 9000 AEI triple quadrupole mass spectrometer operating in timed SRM mode with dwell time prioritization.
• Thermo Scientific TriPlus RSH autosampler for large-volume and splitless injections.
• Chromeleon 7.2 CDS for single-platform acquisition, processing, isotopic-dilution quantitation, and compliant reporting.

Key Results and Discussion

The proprietary TG-Dioxin column achieved baseline separation of all target PCDD/F and PCB congeners in under 45 minutes. Calibration-based LOQs enabled reporting at one-fifth of EU maximum levels, achieving an upper-bound WHO-PCDD/F-TEQ of 0.15 pg/g for a 2 g sample. Response factor (RF) repeatability over four orders of magnitude showed %RSD ≤6% for key congeners. Independent analysis of mixed fat, egg, milk, fish, and feed materials delivered Pearson correlation coefficients >0.99 against EU reference values, with deviations within ±6%. Continuous operation over 161 injections (~2 weeks) without maintenance demonstrated robust sensitivity, stable ion ratios, and RF deviation within regulatory tolerances.

Benefits and Practical Applications of the Method

• Regulatory compliance for PCDD/Fs and dioxin-like PCBs in diverse food and feed matrices.
• High throughput and minimal maintenance ensure laboratory efficiency and uptime.
• Integrated isotopic-dilution calculations and real-time QC in Chromeleon CDS eliminate external spreadsheets and reduce transcription errors.
• Flexibility to handle routine sample loads and proficiency testing requirements.

Future Trends and Potential Applications

Further automation of sample preparation and expanded software workflows may streamline POPs analysis across additional environmental and biological matrices. Advances in instrument sensitivity and high-throughput GC-MS/MS methods could extend reliable quantitation to lower-level contaminants and enable broader biomonitoring studies, while maintaining cost and time efficiency compared to high resolution mass spectrometry.

Conclusion

The TSQ 9000 AEI triple quadrupole GC-MS/MS system, coupled with Chromeleon CDS, delivers a robust, sensitive, and fully integrated solution for routine regulatory analysis of PCDD/Fs and dioxin-like PCBs in food and feed. This approach meets stringent EU regulatory performance criteria, offers high sample throughput, and ensures data integrity through single-platform processing and reporting.

Reference

• World Health Organization. Dioxins and their effects on human health, WHO, 2019.
• Commission Regulation (EU) 2017/644, Official Journal of the European Union, 2017.
• Commission Regulation (EU) 2017/771, Official Journal of the European Union, 2017.
• Guidance Document on Estimation of LOD and LOQ for Contaminants in Feed and Food, European Commission, 2010.
• Directive 2002/32/EC on undesirable substances in animal feed, Official Journal of the European Communities, 2002.
• Regulation (EC) No 1881/2006 on maximum levels for contaminants in foodstuffs, Official Journal of the European Union, 2006.