The typical stationary phases (and their interactions with solutes) are: solids (adsorption), ionic groups on a resin (ion-exchange), liquids on an inert solid support (partitioning), and porous inert particles (size exclusion). The mixture to be separated is loaded onto the top of the column followed by more solvent. The different components in the sample mixture pass through the column at different rates due to differences in their partition behavior between the mobile phase and the stationary phase. The compounds are separated by collecting aliquots of the column effluent as a function of time.
In liquid chromatography, the separator is called the column and consists in most cases of a tube filled with porous material called the stationary phase. A liquid, called the mobile phase, flows through the tube between the particles of stationary phase material. A liquid sample is taken from a mixture to be analyzed and introduced to a part of the system that is at elevated pressure. The sample is then transported to a separator by the flow in the system. After the column the separated compounds enter the detector, which measures a physical or chemical property of each, now relatively pure, compound and creates a proportional electronic signal. By calibrating with a standard mixture of known compounds, the nature of the compound in the mixture can be elucidated.