Principle and fundamental quantities

The principle of gas chromatography is based on the distribution of compounds between a so-called stationary phase, contained in a column, and the mobile phase, the gas that flows through the column. Compounds are subjected to two antagonistic effects:

• retention by the stationary phase (interactions of compounds with the stationary phase) ;

• carrier gas drive.

The migration speed of compounds depends on their affinity for the stationary phase and their volatility. To separate compounds in a mixture, it is necessary to observe a difference in migration speed between them.

The process of eluting compounds from the column can be described as a succession of equilibria, or pseudo-equilibria, between the solute concentration in the stationary phase and...