Gas Chromatography

GC – Instrument Operation• First, a small sample of the material to be analyzed is injected• The sample vaporizes in the injection block and is carried through the column,through the detector, and eventually out of the apparatus.• As the sample is eluted from the column and passed through the detector, oneof the detector wires is exposed to a mixture of carrier gas plus sample, and theother wire is exposed only to the reference stream of carrier gas.• The difference between the two gas streams causes a difference in the electricalconductivity of the wires, and this difference is automatically recorded.• In this way a gas – chromatogram is obtained.