Retention and Selectivity in RP Systems

Reversed-phase liquid chromatography is used in separating polar to medium polar components. Their separation is based on the interaction of the lipophilic part of the solutes with the nonpolar surface groups. Retention depends on the nature of the active groups bonded on the silica surface as well as the functional groups of the solute. The hydrophobicity of reversed-phase packings differs in the relative sequence [Pg.155]

Porous graphitized carbon polymers made from cross-linked styrene/ divinylbenzene n-octadecyl (C18) bonded silicas n-octyl (C8) bonded silicas phenyl-bonded silicas n-butyl (C4) bonded silicas n-propylcyano-bonded silicas diol-bonded silicas. [Pg.155]

In addition to the surface groups of the adsorbent the nature of the functional groups of the solutes determines the interaction and, thus, the retention time as [Pg.155]

Amine/alcohols/phenols acids esters ethers aldehydes/ketones aromatic hydrocarbons aliphatic hydrocarbons. [Pg.156]

Owing to the exothermic behavior of the adsorption, the retention time increases at lower temperatures. An Arrhenius-type equation describes the retention factor s dependence on temperature (Equation 3.14) [Pg.156]