A sustainable approach to nontargeted analysis using hydrogen as a carrier gas for GC×GC

Importance of Topic

Comprehensive two-dimensional gas chromatography (GC×GC) provides exhaustive separation of complex mixtures and is widely used in environmental and forensic analysis. Traditionally employing helium, GC×GC faces supply constraints and sustainability concerns. Substituting hydrogen, a renewable carrier gas producible via water electrolysis, offers reduced environmental impact and operational advantages through faster run times and improved throughput.

Study Objectives and Overview

This work aimed to assess and compare the environmental sustainability of helium and hydrogen GC×GC methods for a 52-component indoor air standard. By translating an established helium-based method into hydrogen equivalents and evaluating their performance with the AGREEprep greenness metric, the study quantifies the benefits of adopting hydrogen in nontargeted analysis.

Methodology and Instrumentation

• Instrument: LECO Pegasus BT4D comprehensive two-dimensional gas chromatograph with time-of-flight mass spectrometry detector.
• Method Translation: Restek EZGC Method Translator generated three hydrogen-based methods prioritizing chromatogram similarity ("Translate"), operational efficiency ("Efficiency"), and speed ("Speed").
• Greenness Assessment: The AGREEprep tool scored each method on ten criteria including sample throughput and carrier gas source, yielding a metric from 0 (least green) to 1 (most green).

Main Results and Discussion

• Run Times: Translate – 27.70 min; Efficiency – 23.20 min; Speed – 19.45 min, compared to helium’s baseline.
• AGREEprep Scores: Hydrogen methods achieved an overall score of 0.52 versus 0.44 for helium, reflecting improved sustainability solely due to carrier gas substitution.
• Chromatographic Quality: All hydrogen methods maintained adequate peak shape and resolution, with the Efficiency method balancing speed and chromatographic fidelity.

Benefits and Practical Applications

• Environmental Impact: Hydrogen is a renewable, low-carbon carrier, reducing reliance on finite helium supplies.
• Operational Efficiency: Shorter analysis times increase sample throughput in high-demand analytical settings.
• Nontargeted Analysis Advantage: Capturing the full sample profile in a single run supports comprehensive screening without multiple targeted assays.

Future Trends and Potential Applications

• Broader Adoption: Translate existing helium methods across laboratories to hydrogen-based protocols using automated tools.
• Quantitative Comparisons: Systematic evaluation of chromatographic performance and detection limits between carrier gases.
• Method Greenness Benchmarking: Employ AGREEprep and similar metrics to optimize other analytical workflows for sustainability.

Conclusion

Replacing helium with hydrogen in GC×GC nontargeted analysis enhances method sustainability, reduces operational costs, and accelerates throughput without compromising data quality. This strategy aligns with green analytical chemistry principles and addresses helium supply challenges.

References

• Wojnowski W, Tobiszewski M, Pena-Pereira F, Psillakis E. AGREEprep – Analytical Greenness Metric for Sample Preparation. TrAC Trends Anal Chem. 2022;149:116553.
• Restek. EZGC Method Translator and Flow Calculator Help. Accessed December 8, 2025.