Working principle of Gas Chromatography (GC)

Gas Chromatography is a common type of chromatography which is used for separating and analyzing the compound. The compound gets separated based on vapourisation without being decomposed. GC helps to separate the different components of the mixture and also in identifying a compound in a mixture by their different elution time which also called retention time (RT).

When a sample is injected from an injector port, it gets vaporized from the liquid phase because of the high temperature of the injector port. After injecting a sample it goes from liner to column. Inside the column, there is a component called stationary phase (eg:- 5% phenyl polysiloxane) that helps in separating the components on the basis of their interaction with the stationary phase (the compound that interacts in the stationary phase elutes later as compared to that which doesn't interact). The mobile phase is a carrier gas in gas chromatography. An inert gas such as Helium is used as the carrier gas. 

With the help of stationary phase and mobile phase compound gets separated and elutes with their retention time. When a compound elutes from the column, it gets detected on the detector and the peak of the compound shows on the computer screen.