The carrier gas of a gas chromatograph is very important. It varies for the gas chromatograph used, but in general the gas must be chemically inert, dry, and free of oxygen. These conditions are required because otherwise the carrier gas might chemically react and interfere with the surface of the gas chromatograph or the gases being studied.
The carrier gas has 2 purposes:
The Huygens GCMS uses approximately 3 standard liters (about 0.8 gallons) hydrogen gas as carrier gas. This quantity allows for the planned 2 to 3 hour descent sequence and provides a 50% reserve. Once the hydrogen gas is turned on, it remains on throughout the mission, continually flowing through the GCMS.