Helium Conservation and Converting GC Methods to Nitrogen and Hydrogen Carrier Gas

Importance of the Topic

Gas chromatography relies heavily on high-purity helium, yet global shortages and rising costs threaten routine operation. Efficient helium conservation and the transition to alternative carrier gases such as nitrogen or hydrogen are critical to maintain analytical performance, reduce expenses, and support sustainability.

Study Objectives and Overview

This work outlines a decision framework for selecting carrier gases, describes hardware and software innovations to conserve helium without revalidating existing methods, and presents best practices for migrating established helium-based GC and GC/MS procedures to nitrogen or hydrogen while preserving resolution and quantitative accuracy.

Methodology and Used Instrumentation

Key approaches include:

• A carrier-gas decision tree to guide users through the choice of helium conservation or method migration.
• Integration of a Helium Conservation Module on the Agilent 7890B GC, enabling automatic switch-over to nitrogen during idle periods and seamless return to helium in 15–30 minutes.
• Use of built-in method translation calculators within ChemStation or OpenLAB CDS to adjust column flow or holdup time, maintaining retention times and peak order.
• Case studies converting ASTM D6584 (glycerin analysis) and ASTM D4815 (gasoline oxygenates) from helium to nitrogen and hydrogen.

Used Instrumentation

• Agilent 7890B Gas Chromatograph with 5th-generation EPC and Sleep/Wake control module.
• Helium Conservation Module and Helium Gas Saver option.
• Agilent 5773 and 5975 Mass Selective Detector and 6890/7890 GC platforms.
• Flame ionization detector (FID) with nitrogen makeup and thermal conductivity detector (TCD).
• Hydrogen generator (>99.9999% purity) or high-purity cylinders with inline filters.

Main Results and Discussion

Helium Conservation Module results:

• Idle-time helium consumption reduced by over 80%, extending cylinder life from ~2 months to >12 months and lowering annual gas costs by ~75%.
• No method revalidation required; chromatographic performance (peak shape, resolution, retention time) remains unchanged after nitrogen sleep cycles.

Migrating to nitrogen:

• Using constant holdup time translation, retention times in ASTM D6584 and D4815 agree within 0.2% of helium methods.
• Quantitative results for glycerides and ethers/alcohols show deviations <2% of original helium-based values.

Migrating to hydrogen:

• Hydrogen offers the fastest separations but requires safety interlocks, flow-limiting frits, and system purging protocols.
• GC/MS-specific considerations include reduced sensitivity (2–5×), initial hydrocarbon background, overnight source cleanup, and lens/magnetic element upgrades.

Benefits and Practical Applications

• Substantial cost savings and reduced dependency on scarce helium supplies.
• Minimal changes to existing methods, preserving regulatory compliance and laboratory workflows.
• Flexibility to choose nitrogen for routine or less resolution-critical analyses and hydrogen for high-throughput or resolution-demanding separations.

Future Trends and Potential Applications

Anticipated developments include tighter integration of carrier-gas switching into GC control software, broader adoption of on-site hydrogen generators with advanced safety features, AI-driven carrier-gas selection algorithms, and expansion of multi-dimensional GC methods optimized for alternative gases to further enhance separation power and sustainability.

Conclusion

Agilent’s combination of hardware, software, and methodological guidance provides laboratories with practical pathways to dramatically reduce helium usage or fully migrate to nitrogen or hydrogen carriers without sacrificing data quality. These strategies address supply uncertainties, cut operational costs, and align with sustainable laboratory practices.

Reference

• McCurry JD. Helium Conservation and Helium Shortage for Converting GC Methods to Nitrogen and Hydrogen Carrier Gas. Agilent Technologies; July 30, 2013.