Other New Methods of Column Chromatography

A type of chromatography recently reported, termed micellar liquid chromatography or soap chromatography, utilizes micelles as a component of the mobile phase. The partitioning of solute components into the micelles can be used as a 

The fundamentals of micellar chromatography are similar to those of ion-pair chromatography with the formation of a solute-micelle complex replacing that of an ion pair. The surfactant concentration is maintained above the critical micelle concentration (CMC) in the mobile phase so that micelles, either cationic as with cetyltrimethylammonium bromide, or anionic as with sodium dodecylsulfate, are present. The separation of solute components thus reflects a composite of their partitioning characteristics between the micelles and the mobile phase, between the micelles and the stationary phase, and between the stationary phase and the mobile phase. 

The theoretical and parameter-optimization aspects have been examined and reveal that micellar chromatography can uniquely complement ion-pair chromatography (11). Thus, while ion-pair chromatography allows retention and ultimately separation of solute components - which would not otherwise be retained and, hence, not resolved - micellar chromatography reduces the retention of solute components that otherwise would not be transported via partitioning into the mobile micelles (10, 130, 402). 

Two types of micellar chromatography are possible. For neutral solutes, a normal micelle with nonpolar interior and ionic surface, in an aqueous mobile phase against a reversed-phase solid support is used (10, 130, 402). The solute components, which may not be water soluble and would be adsorbed irreversibly on the reversed-phase support, are transported by partitioning into the nonpolar interior of the micelle. This type of micellar chromatography has been successful in separating pesticides, polynuclear aromatic compounds, and other model solutes (10, 130, 402). 

For polar or charged solute components, reversed micelles, ionic interior with entrapped water molecules and a non-polar exterior, in an organic solvent mobile phase against a normal phase solid support is used. In this case, the solute molecules, such as nucleosides and amino acids, which normally would not be transported by an organic solvent, are mobilized by partitioning into the interior of the reversed micelle (12). 

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