Hydrogen: A Superior Carrier Gas Alternative to Helium

Significance of the Topic

Gas chromatography relies on an inert carrier gas to transport analytes through the column. With global helium shortages and rising costs, hydrogen emerges as a compelling alternative. Its higher diffusivity and broader optimal linear velocity range offer faster analyses, making it relevant for laboratories facing supply challenges and seeking improved throughput.

Study Objectives and Overview

This application note investigates hydrogen’s performance as a carrier gas in temperature‐programmed GC compared to helium and nitrogen. The study evaluates analysis speed, separation efficiency, cost factors, and practical safety considerations using a set of 16 polynuclear aromatic hydrocarbons (PAHs).

Methodology

The separation employed a 15 m × 0.10 mm I.D., 0.10 µm Equity-5 capillary column under a rapid temperature program (100 °C for 1 min, ramp at 35 °C/min to 325 °C, hold 5 min). A 1 µL sample injection (200 ppm analytes in methylene chloride, split ratio 200:1) was performed at 250 °C, with flame ionization detection at 350 °C. Helium was tested at 20 cm/sec linear velocity; hydrogen at 45 cm/sec.

Used Instrumentation

• Equity-5 capillary column (15 m × 0.10 mm I.D., 0.10 µm film)
• GC injector with split cup liner
• Flame ionization detector (FID)
• Hydrogen and helium gas generators (PEM and ChromGas, Nitrox models)

Main Results and Discussion

Switching from helium to hydrogen at optimal velocities reduced total runtime by approximately 25%, cutting analysis time from about 12 minutes to under 9 minutes. Hydrogen’s flatter Golay efficiency curve allows operation above optimal velocity with minimal loss of theoretical plates, further shortening runtimes without compromising resolution.

Benefits and Practical Applications

• Speed: Higher diffusivity yields faster separations over a wide velocity range.
• Efficiency: Maintains peak performance even at elevated flow rates.
• Cost: On‐site hydrogen generation reduces dependency on expensive helium cylinders.
• Safety & Convenience: Gas generators operate at low pressure (<125 psi), minimize cylinder handling risks, and require less storage space.

Future Trends and Potential Applications

Advances in safe, compact hydrogen generators will drive broader adoption in routine GC workflows. Integration with ultra‐fast GC methods may further enhance throughput. Emerging safety sensors and automated shutdown features will address risk concerns, while coupling hydrogen GC with mass spectrometry promises expanded application in trace analysis and environmental monitoring.

Conclusion

Hydrogen combines superior speed, sustained efficiency across variable flow rates, and cost advantages, provided appropriate safety measures are in place. It represents a superior carrier gas for temperature‐programmed GC when compared to helium and nitrogen.

References

• Sigma-Aldrich. Application Note 184: Hydrogen: A Superior Carrier Gas Alternative to Helium.
• Sigma-Aldrich. Fast GC: A Practical Guide for Increasing Sample Throughput without Sacrificing Quality.
• Sigma-Aldrich. Gas Generators: Generate High Purity Gas with Reliability and Safety.