Mobile phase – serves as carrier for the injected sample to the column and leads separated components to the detector. In Gas Chromatography mobile phase comprises of separate gas streams-inert gas such as nitrogen or helium, oxidant which is generally air and fuel gas which is usually hydrogen. The three are pre-mixed in the required proportion before being led to the system.
Sample injector – manual or automatically controlled injection system which injects constant sample volume each and every time. Liquid sample mixtures are injected with a gas tight syringe and gaseous mixtures are injected with automated injection valves.
Column –Columns in GC are generally longer and narrower than HPLC columns. These are filled with the stationary phase or the inside wall is coated. Depending on selective adsorption of separated components selective retention takes place.
Detector – Most commonly used detector is the flame Ionisation detector(FID), in which the separated components get ignited in the flame and detector response is dependent on current generated due to compound ionization..Other common detectors are TCD, ECD and FPD.
Data station –Today’s GC systems use a computer to control system parameters such as flow rate, injection sequence and volume, wash cycles, column pressure, detector wavelength, etc and at same time calculate and display the parameters. Chromatograms and results are displayed and printed using user friendly application softwares developed by different manufacturers.