The Classification Of HPLC Column
The frequently used HPLC columns are packed with silica, which is divided into normal phase columns and reversed-phase columns. Other packing columns are also available in polymer fillers and inorganic fillers.
The stationary phase for normal phase chromatography is typically silica gel and other bonded phase fillers with polar functional groups. As the silicon hydroxy group (SiOH) or other polar groups on the surface of the silica gel are relatively polar, the order of separation is based on the polarity of each component in the sample, that is, the component with weak polarity is first washed out.
The packing for the reverse phase column is usually based on silica gel with a bonded phase bonded to a relatively weakly polar functional group. The mobile phase used in reverse phase HPLC column is more polar, which is usually a mixture of water, buffer and methanol, acetonitrile, and the like.
The order in which the sample exits the column is that the more polar component is first washed out, while the less polar component is more retained on the column. Commonly used reverse packing materials are C18 (ODS), C8 (MOS), C4 (Butyl), C6H5 (Phenyl) and the like.