When the polarity of the stationary phase is greater than the polarity of the mobile phase, it can be called normal phase partition chromatography or simply normal phase chromatography.
If the polarity of the stationary phase is less than the polarity of the mobile phase, it can be called reversed phase partition chromatography or simply reversed phase chromatography.
For normal phase chromatography, a low polarity mobile phase such as n-hexane can be used. For reverse phase chromatography, a strong polar mobile phase of methanol or water can be used. The stationary phase for normal phase chromatography is usually silica gel. Silica and other polar functional group amine groups, due to the strong polarity of silanol groups (SiOH) or other polar groups on the surface of the silica gel.
In the normal phase mode, ethyl acetate + n-hexane, dichloromethane + n-hexane, isopropanol + n-hexane, etc. are most commonly used as the mobile phase. A column usually made of NH2, APS and a cyano group (CN, CPS) as a bonded phase filler is called a normal phase column. Hawach’s normal phase columns are CN HPLC Columnsand NH2 HPLC Columns.
The packing for reversed-phase chromatography is usually based on silica gel, and the surface is bonded to the bonded phase with relatively weak functional groups. The commonly used reverse packings are C18 (ODS), C8 (MOS), C4 (Butyl), C6H5 (Phenyl), etc. In the reverse phase, an aqueous solution of methanol, acetonitrile or the like is used. Columns made of this packing are called reversed phase columns. Hawach’s reversed phase columns are C18 HPLC Columns, C8 HPLC Columns, and Phenyl HPLC Columns.
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