Stationary Phases Used in Liquid-Liquid Column:

In liquid-liquid column chromatography, the stationary phase is a liquid which is immobilized on an inert support. A stationary phases fall within two classes: the more general hydrophilic ones and the reversed phase. A stationary or supported liquid phase has been of several types varying in polarity from water to paraffin hydrocarbons. As a huge number of liquid stationary phases can be held mechanically on an inert support, like stationary phases have a few drawbacks like leaching out of the liquid stationary phase from the inert support. In order to eliminate such disadvantages, surface-reacted or bonded stationary phases have been developed. The advantages of these materials are that pre-columns and or presaturation of the two phases are not required. Further packing along with bonded stationary phases is quite stable because there is no opportunity for the chemically bound stationary phase to be eluted during use. A drawback of bonded-phase packing is a lack of systemic information regarding the mode of retention for solutes. There are two types of surface-reacted or bonded stationary phases that are now commercially available. The first one is an esterified siliceous material e.g. Durapak and the second type is surface reacted packing e.g. Bondpack, Vydac (organic coating is a monomolecular), Permaphase (organic coating is of many layers). Columns of bonded phase packings have been used continuously for many months without changes in chromatographic characteristics. Those bonded phase materials are available along with various kinds of functional groups and used for separations of several types of solutes.