Varian 450-GC, User Manual

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Flame Ionization Detector (FID) - Detectors
Varian, Inc. User Manual 450-GC Page: 283
FLAME IONIZATION DETECTOR (FID)
The flame ionization detector (FID) is the most sensitive gas chromatographic
detector for hydrocarbons such as butane or hexane. With a linear range for 6
or 7 orders of magnitude (10
6
to 10
7
) and limits of detection in the low picogram
or femtogram range, the FID is the gas chromatographic detector for volatile
hydrocarbons and many carbon containing compounds.
The FID detector employs hydrogen as the combustion gas which is mixed with
Air and the column eluent (helium, nitrogen or other appropriate gas) and burn
at a small jet situated inside a cylindrical electrode. A potential of a few hundred
volts is applied between the jet and the electrode and when a carbon containing
solute is burn in the jet, the electron/ion pairs that are formed are collected at
the jet and cylindrical electrode.
The following instructions refer to the operation of a 450-GC Flame Ionization
Detector (FID). The FID is installed on a detector base, directly above the
column oven. The FID electrometer is installed in the electronics cabinet on the
left of the instrument. The electronics of the FID are controlled from the 450-GC
Display/Keyboard, the gas flows are set and controlled either from the 450-GC
Display/Keyboard (if detector EFC is installed) or at the pneumatics panel.