The stationary phase is present during chromatography where a Solvent[] or mobile phase is allowed to flow over the stationary phase, thus allowing some molecules in the mobile phase to attach to the stationary phase thus ensuring separation. The binding to the stationary phase depends on the moleules affinity for the phase. The componets of the stationary phase depends on the type of chromatography. E.g. for gas chromotography it is typically either glass, silica, or alumina.