Uncompromised sensitivity in polychlorinated dibenzo-p-dioxins/furans analysis using triple quadrupole GC-MS with cost-effective helium-saving technology

Importance of the topic

Polychlorinated dibenzo-p-dioxins/furans (PCDDs/PCDFs) are persistent, highly toxic contaminants that pose serious health risks even at sub-picogram per gram concentrations. Regulatory agencies require ultra-trace detection in environmental and food samples. Helium, the conventional GC carrier gas, delivers optimal chromatographic performance but faces global supply shortages and rising costs, threatening method reliability and laboratory budgets.

Objectives and Study Overview

This study assessed the Thermo Scientific HeSaver-H2Safer technology integrated into an iConnect split/splitless injector on a TRACE 1600 Series GC coupled to a TSQ 9610 triple quadrupole MS. The objective was to demonstrate substantial helium savings without compromising sensitivity, precision, or compliance with EPA Method 1613 and EU regulations for PCDD/F analysis.

Methodology and Instrumentation

Sample Preparation:

• 2 g soil extracted in acetonitrile/hexane (4 mL:4 mL), centrifuged at 3 000 rpm.
• 100 µL hexane layer dried, spiked with lowest calibration standard, reconstituted in nonane to 100 µL.

Calibration:

• Six-level isotopically labeled EPA-1613 standards diluted to generate calibration from 0.01 to 0.1 pg/µL for LOQ evaluation.

Instrumentation:

• GC: TRACE 1610 with HeSaver-H2Safer iConnect SSL injector (nitrogen pressurizing gas, helium carrier limited to 1.2 mL/min).
• Column: TraceGOLD TG-Dioxin 60 m × 0.25 mm × 0.25 µm film.
• Autosampler: TriPlus RSH automated liquid injector.
• MS: TSQ 9610 triple quadrupole with Advanced Electron Ionization source, timed-SRM acquisition, Argon collision gas at 70 psi.

GC oven and MS parameters were set to meet retention time tolerance (±0.01 min), ion ratio (±15 %), and relative response factor (±20 %) criteria.

Key Results and Discussion

Injection Repeatability:

• 69 injections in one sequence: <10 % RSD in absolute peak area.
• Additional 31 injections over two days without maintenance: <8 % RSD.

Sensitivity and Selectivity:

• LOQ/2 check standards (5–50 fg/µL) met all regulatory criteria at fg levels.
• Extracted SRM in raw soil matrix showed clear detection without cleanup.
• Quantified spiked congeners matched target values within 7 fg, except those present natively in the soil.

Helium Consumption:

• HeSaver-H2Safer injector reduced helium use by 7.6× compared to standard SSL.
• Extended helium cylinder life from 0.25 years to 1.8 years under continuous operation, with long-term savings exceeding USD 10 000 over 10 years.

Benefits and Practical Applications

• Maintains uncompromised sensitivity and selectivity for PCDD/F analysis at trace levels.
• Delivers robust intra- and inter-day precision without method reoptimization.
• Mitigates helium supply challenges and reduces operational costs.
• Offers easy retrofit to existing GC-MS systems without additional sensors.

Future Trends and Potential Applications

Wider adoption of gas-saving injector technologies is anticipated, including compatibility with hydrogen carriers for further cost reduction. Enhanced integration with high-resolution MS platforms and advanced data workflows will improve throughput and compliance. Sustainable laboratory practices will drive implementation in environmental monitoring, food safety, and industrial quality control.

Conclusion

The HeSaver-H2Safer technology paired with the TSQ 9610 GC-MS/MS delivers reliable fg-level sensitivity, robust precision, and significant helium savings, ensuring regulatory compliance and enabling sustainable laboratory operations without methodological compromise.

References

1. United States Environmental Protection Agency. Method 1613: Tetrachloro-through Octachlorinated Dioxins and Furans by Isotope Dilution HRGC/HRMS (1994).
2. European Commission Regulation 2017/644: Methods for Dioxins and Dioxin-like PCBs in Food and Feed.
3. European Commission Regulation 2017/771: Amendments to Regulation 152/2009 for Dioxins and PCBs Analysis.
4. Thermo Fisher Scientific. Technical Note 001218: Gas Conservation with HeSaver-H2Safer on TRACE 1600 Series.