Partition Chromatography Modifications

Wick, C.D., Siepmann, J.I., and Schure, M.R., Simulation studies on the effects of mobile-phase modification on partitioning in liquid chromatography, Anal. Chem., 76, 2886, 2004. 

The great versatility of HPLC is evidenced by the fact that all chromatographic modes, including partition, adsorption, ion exchange, chromato-focusing, and gel exclusion, are possible. In a sense, HPLC can be considered as automated liquid chromatography. The theory of each of these chromatographic modes has been discussed and needs no modification for application to HPLC. However, there are unique theoretical and practical characteristics of HPLC that should be introduced. 

Chromatography, a physical method of separation in which the components are partitioned between two phases, was invented simultaneously and independently by American geologist D.T. Day and Russian botanist M.S. Tsvet (Tswett). Their methods and later modifications are described in Vol 3 of Encycl, pp C289 to C298. Qualitative method of separation of ingredients by adsorption was known for centuries. This is described on p C289-R... 

Another modification of CE is micellar electrokinetic chromatography (MEKC), which is widely used for the separation of nonpolar compounds. The molecules in question partition into micelles (nonpolar layer) with mechanisms similar to those observed with reverse-phase chromatography. An anionic surfactant, sodium dodecyl sulfate, is commonly used as a micellar... 

As mentioned above ion-pair partition is automatically involved in chromatography of anionic solutes on dynamically coated phases using long chain quaternary ammonium ions. The possibility of ion-pair partition of cationic solutes, however, has not been investigated and problems might occur due to the apparent possibility of ion-pair formation between the counterion and surfactant ions, as well as the solute in question. A dynamic modification of the support surface (alumina), using... 

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