Dioxin 2019: Flexible Automated Sample Clean up of PCDD/Fs and PCBs

Significance of the Topic

Organochlorinated pollutants such as PCDD/Fs and PCBs pose serious environmental and health risks due to their persistence and toxicity. Reliable, high-throughput clean-up methods are essential to meet regulatory limits and support routine monitoring in food and environmental samples.

Objectives and Study Overview

This work introduces a flexible automated sample clean-up platform tailored for the simultaneous and selective isolation of dioxins and PCBs. The study aims to compare multiple clean-up workflows across different oil matrices to assess recovery, throughput, and adaptability to various target analyte combinations.

Methodology

Sample Preparation:

• Five grams of oil (fish, corn, olive) dissolved in n-hexane.
• Addition of 13C-labelled extraction standards.

Automated Clean-up:

• DEXTech Pure system with electrically locked column tower and click-in ready-to-use columns (acidic silica, alumina, activated carbon or Florisil).
• Multiple fractionation methods: Universal Plus, Universal Pure, PCB-only, dioxin-only.

Evaporation and Concentration:

• D-EVA vacuum centrifuge with cold trap for controlled evaporation to final volumes of 30–100 μL (PCDD/F) or 300–500 μL (PCB).

Analysis:

• GC-HRMS on Thermo Fisher DFS system.

Main Results and Discussion

All methods achieved high 13C-labeled recoveries (>80%) across oil types. The Universal Plus workflow provided slightly higher recoveries, while PCB-only and dioxin-only protocols demonstrated efficient selective isolation with minimal cross-contamination. Automation reduced variability and operator workload significantly.

Practical Benefits

• High throughput: up to 16 samples processed sequentially without supervision.
• Reduced hands-on time and low per-sample costs due to reusable columns and minimal solvent usage.
• Full compliance with EU and EPA reference methods.
• Flexible fractionation enabling tailored workflows for different target analyte sets.

Used Instrumentation

• DEXTech Pure automated clean-up system.
• D-EVA vacuum centrifuge (LCTech) for sample evaporation.
• GC-HRMS (Thermo Fisher DFS).

Future Trends and Applications

Further developments will focus on separation of comprehensive PCB congener profiles (including PCB 209), expansion to polyhalogenated contaminants (PCNs, HBCDD), and adaptation to stricter regulatory limits requiring larger sample loads.

Conclusion

The described automated platform provides a versatile, reliable, and high-throughput solution for PCDD/F and PCB clean-up. Its modular design and automation capabilities support a broad range of analytical protocols, enhancing laboratory efficiency and data quality.