13
Site Preparation
Gas requirements
Table 5. Gas Recommendations for Capillary Columns
Gas purity
Some gas suppliers furnish “instrument” or “chromatographic” purity grades of
gas that are specifically intended for chromatographic use. We recommend these
grades for use with the GC.
Detector Carrier gas
Preferred
makeup gas
Second choice Detector, anode purge,
or reference gas
Electron
Capture
Hydrogen Argon/Methane Nitrogen Anode purge must
be same as makeup
Helium Argon/Methane Nitrogen
Nitrogen Nitrogen Argon/Methane
Argon/Methane Argon/Methane Nitrogen
Flame
Ionization
Hydrogen Nitrogen Helium Hydrogen and
air for detector
Helium Nitrogen Helium
Nitrogen Nitrogen Helium
Flame
Photometric
Hydrogen Nitrogen Hydrogen and air for
detector
Helium Nitrogen
Nitrogen Nitrogen
Argon Nitrogen
Nitrogen-
Phosphorus
Helium Nitrogen Helium** Hydrogen and
air for detector
Nitrogen Nitrogen Helium**
Thermal
Conductivity
Hydrogen* Must be same
as carrier and
reference gas
Must be same
as carrier and
reference gas
Reference must be
same as carrier and
makeup
Helium
Nitrogen
* When using hydrogen with a thermal conductivity detector, vent the detector exhaust to a fume hood or a dedicated
exhaust to avoid buildup of hydrogen gas.
**H elium is not reco mmended a s a makeup g as at flow rates> 5 mL /min. Fl ow rates ab ove 5 mL/min shorten d etecto r life.
To Next Page
Loading...
