Carrier Gas
Definition
The inert mobile phase that sweeps the sample through the column. Helium is traditional and gives the best peak shape on capillary columns, hydrogen is faster and cheaper but flammable, nitrogen is the budget option used mostly with packed columns.
- Function
- Inert mobile phase that moves sample through the column
- Helium
- Traditional choice, best peak shape on capillary columns
- Hydrogen
- Faster and cheaper but flammable
- Nitrogen
- Budget option, mostly with packed columns
Common questions
Why has helium supply become a concern for GC laboratories?+
Helium is a finite, non-renewable resource extracted alongside natural gas, and periodic global shortages and price spikes have pushed many labs to validate hydrogen or nitrogen as substitutes despite their handling tradeoffs.
What is the practical downside of switching carrier gas from helium to hydrogen?+
Hydrogen is flammable and requires leak detection and safety precautions around the instrument, and switching gases changes optimum flow rates and can shift retention times, so methods need re-validation rather than a direct swap.
Related terms
- Capillary Column
- A fused silica tube 15 to 60 m long with an internal diameter of 0.25 to 0.53 mm and a stationary liquid...
- Derivatisation
- A pre-injection chemical step that converts polar, non-volatile or thermally fragile analytes into volatile, GC-friendly derivatives. Silylation with BSTFA is the most...
- ECD
- Electron capture detector. A Ni-63 radioactive source produces a baseline electron current that is reduced when electron-affinic species (halogens, nitro groups, peroxides)...
- FID
- Flame ionisation detector. A hydrogen-air flame ionises C-H bond containing analytes and a collector electrode reads the ion current. Near-universal for organic...
- Headspace GC
- Gas chromatography in which the sample (blood, urine, vitreous) is sealed in a vial, equilibrated at a fixed temperature, and a portion...