Comparison of Separation Performance with Various Carrier Gases

Importance of the Topic

Gas choice in gas chromatography critically influences separation quality, analysis speed and laboratory throughput. Comparing hydrogen, helium and nitrogen carrier gases on a polar wax column demonstrates their impact on efficiency, resolution and operational flexibility.

Study Objectives and Overview

This study evaluates the separation performance of a Grob test mixture comprising 10 components (including decane, nonanal and dicyclohexylamine) using an SH-PolarWax column. Three carrier gases (H2, He, N2) were compared under controlled linear velocities to assess retention times, peak shape and analysis time.

Methodology and Instrumentation

The analysis employed a Shimadzu Nexis GC-2030 system with AOC-20i Plus autosampler. Key parameters:

• Injection: split mode (1:39), 0.5 µL at 260 °C
• Column: SH-PolarWax, 30 m × 0.25 mm I.D., 0.50 μm film thickness
• Temperature program: 70 °C (2 min), ramp to 180 °C at 20 °C/min, then to 200 °C at 5 °C/min (15 min hold)
• Detector: FID at 260 °C; H2 (32 mL/min) and air (200 mL/min) makeup gas (24 mL/min)
• Carrier gas control: linear velocity set to 20, 30, 40 and 50 cm/s

Key Results and Discussion

Hydrogen provided the fastest elution and sharpest peaks due to its high diffusivity, reducing overall run time while maintaining resolution. Helium offered balanced performance with moderate analysis speed and peak symmetry. Nitrogen showed extended retention and broader peaks at equivalent velocities, indicating less efficiency at high throughput demands. Adjusting linear velocity highlighted the trade-off between speed and resolution for each gas.

Benefits and Practical Applications

Hydrogen enables rapid analyses and improved resolution but requires proper safety protocols and generator infrastructure. Helium remains a reliable compromise when supply and safety are priorities. Nitrogen may suit low-throughput or cost-sensitive applications where speed is less critical.

Future Trends and Opportunities

Growing adoption of hydrogen generators and alternative gas supplies will support sustainable, high-throughput GC. Advances in column chemistries and AI-driven method optimization will further refine gas selection strategies. Integration of micro GC systems may also benefit from low-viscosity gases.

Conclusion

This comparative study confirms that carrier gas choice significantly affects chromatographic efficiency. Hydrogen yields superior speed and resolution, helium balances performance and convenience, while nitrogen is limited by diffusion constraints. Labs must weigh safety, cost and throughput when selecting carrier gases.

Reference

• Shimadzu Corporation. Application News G328 (JP/ENG), First Edition Sep. 2022.