The partition chromatography of flash column implements the separation by using the difference of components’ solubility between the immobile phase and mobile phase.
Commonly, the immobile phase is a liquidus solvent. It uses bonding and adsorption to distribute in the flash column or the surface of the supporter. In fact, the process of partition chromatography is a process in which the components continue to reach solubility equilibrium between the immobile phase and the mobile phase.
In general, the carriers of liquid-liquid partition chromatography mainly include silica gel, infusoria earth, and cellulose. Normally, when we separate water-soluble components or components with strong polarities, such as natural base, glycoside, saccharides, and organic acid, we mostly take solvents with strong polarity, including water and buffer solution, as the immobile phase. As for the mobile phase, we often use formyl trichloride, ethyl acetate, and butyl alcohol. On the whole, this is called normal-phase chromatography of the flash column.
On the other side, when we separate fat-soluble chemical compounds, such as higher aliphatic acid, grease and free steroidal, we can take paraffin oil as the immobile phase. Relatively, we take solvents with strong polarity including water and methyl alcohol, as the mobile phase. This is called reverse-phase chromatography of the flash column.