Instrumentation Mobile phases are generally inert gases such as helium, argon, or nitrogen. The injection port consists of a rubber septum through which a syringe needle is inserted to inject the sample. The injection port is maintained at a higher temperture than the boiling point of the least volatile component in the sample mixture. Since the partitioning behavior is dependant on temperture, the separation column is usually contained in a thermostat-controlled oven. Separating components with a wide range of boiling points is accomplished by starting at a low oven temperture and increasing the temperture over time to elute the high-boiling point components.
Most columns contain a liquid stationary phase on a solid support.
Separation of low-molecular weight gases is accomplished with solid adsorbents. Separate documents describe some specific GC Columns and GC Detectors .