CHROMATOGRAPHY GASES

Carrier gases
O and H O are key impurities especially for capillary colums.
Hydrogen gives fastest analysis in capillary GC

Fuel gases
Used in some detectors, mainly FID
Mainly hydrogen and air
Hydrocarbons critical for FID

Make-up gas
Sometimes used with capillary GC
Added between column and detector
Ensures optimum detector sensitivity

EFFECT OF IMPURITIES IN GASES IN CHROMATOGRAPHY
Reduced column life by contaminants such as oxygen and water
Baseline noise
Detector quenching
Detector life, stability and sensitivity compromised
Downtime

PROBLEMS WITH SYSTEMS USING CYLINDER GAS AND PURIFIERS
Purifiers only remove some contaminants, and may add other contaminants.
Joints in piping may leak.
Most systems need downtime for purifier change.
Some systems have contamination introduced when changing purifier.
Purifiers are expensive.
Some purifiers are non-indicating, with possibility to column destruction before user knows.
that the purifier is finished.
Saturation of purifier occurs suddenly, and impurity level rises rapidly destroying columns.