Page 28 - Tandem Techniques
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largely on the type of detector that is being used. If a katherometer detector (hot wire detector) is
employed, a single gas supply of helium will be adequate. Conversely, if a flame ionization detector
(FID) is used, then a three-component gas supply will be necessary comprised of hydrogen and air for
the FID and helium (or occasionally nitrogen) for the mobile phase (commonly called the carrier gas).
The different gases pass to appropriate flow controllers, one for each gas supply, and that from the
carrier gas controller passes to a heated injection system, where the sample is introduced onto the
column.
Figure 11.
A Block Diagram of a Gas Chromatograph
