Advantages and Disadvantages of Substitution of Helium as Carrier Gas in Gas Chromatography by Hydrogen. Part III. – Sample Introduction and Detectors

Importance of the Topic

Gas chromatography (GC) is one of the most widely used techniques in brewing and food analysis. Helium has traditionally been the preferred carrier gas, but recent supply shortages and rising costs have driven the search for reliable alternatives. Hydrogen offers higher linear velocity, improved separation efficiency and reduced analysis time, making it an attractive replacement for helium in routine and advanced GC applications.

Objectives and Overview of the Study

This third part of a series evaluates the specific considerations when switching from helium to hydrogen for sample introduction and detector performance. It reviews common injection modes, head-space techniques and the impact of hydrogen on the most frequently used detectors in brewing analytics. Practical guidelines are offered for method adjustment and parameter optimization.

Methodology and Instrumentation

The study discusses:

• Split/Splitless injection systems: comparison of split and splitless modes, adjustment of split ratios when using hydrogen’s higher carrier velocity.
• Static and dynamic head-space sampling: safety considerations, use of nitrogen for vial pressurization and syringe purging, purge-and-trap workflows.
• Purge-and-Trap and Thermal Desorption Cold Trap injectors for carbonyl compounds.
• Detectors: flame ionization detector (FID), flame photometric detector (FPD), electron capture detector (ECD) and mass spectrometry (MS) considerations under hydrogen flow.

Main Results and Discussion

Switching to hydrogen as carrier gas yields sharper, narrower peaks due to faster analyte transfer and reduced longitudinal diffusion. In splitless injection, detection limits improve as sample vapor is introduced more rapidly. Dynamic head-space performance remains comparable, provided vial pressurization uses an inert purge gas. FID and FPD detectors tolerate hydrogen as carrier and fuel gas when proper stoichiometry of hydrogen-to-air is maintained; nitrogen remains the preferred make-up gas. ECD requires inert carrier and make-up gases, so hydrogen cannot replace nitrogen or argon in this detector. In MS systems, hydrogen’s lower viscosity increases solvent expansion in the injector but can be managed with narrow-bore columns and optimized flow to maintain vacuum and spectral integrity.

Benefits and Practical Applications

Adopting hydrogen:

• Reduces operational costs compared to helium.
• Improves chromatographic efficiency and throughput.
• Retains compatibility with standard FID and FPD detectors when air and make-up flows are optimized.
• Supports rapid screening of volatile compounds and flavor markers in beer quality control.

Future Trends and Applications

Growing deployment of on-site hydrogen generators will ensure consistent high-purity supply. Advances in safety monitoring, miniaturized GC modules and integration with tandem MS will further expand hydrogen’s role in high-volume brewery QA/QC labs and research. Development of detector designs tolerant to hydrogen make-up could broaden its use in ECD-like systems.

Conclusion

Hydrogen is a viable replacement for helium in most gas chromatographic workflows. It offers economic and performance advantages but requires careful adjustment of injection parameters and detector gas flows. Proper safety measures and equipment configuration ensure reliable analytical results, especially in brewing industry applications.

Reference

• Čulík J., Figalla K., Horák T., Kellner V. (1999) Determination of volatile higher alcohols in beer by SPE and GC. Kvasny Prum 45: 4–7.
• Čulík J. et al. (2009) Determination of aromatic alcohols in beer by SPE–GC–MS. Kvasny Prum 55: 177–186.
• Horák T., Čulík J., Jurková M., Kellner V. (1999) Chlorinated aliphatic hydrocarbons in beer. Kvasny Prum 45: 317–320.
• Heseltine J.V. (2010) Hydrogen as a carrier gas for GC and GC–MS. LCGC North America 28: 16–19.
• Kolb B., Ettre L.S. (2006) Static headspace–gas chromatography: theory and practice. Wiley, Chichester.