HPLC is best described as high performance liquid chromatography since the essence of the technique is the highly resolutive separations which can be achieved by the use of uniform microparticulate chromatographic supports and well designed equipments. Two mutually immisible phases are brought into contact wherein one phase is stationary and other is mobile. The sample mixture, introduced into the mobile phase, undergoes series of interactions (partitions) many times between the stationary and mobile phases as it is being carried through the system by the mobile phase. Partition takes place by adsorption- desorption techniques. Interactions exploit differences in the physical and chemical properties of the components in the sample. These differences govern the rate of migration of the individual components under the influence of the mobile phase moving through a column containing stationary phase. Separated components emerge in the order of increasing interaction with the stationary phase.