In normal phase chromatography, a polar bonded stationary phase is generally employed, and the surface of the silica gel is bonded to a polar organic group, and the name of the bonded phase is determined by the bonded group. The most commonly used are cyano (-CN), amino (-NH2), and diol (DIOL) bonded phases. Therefore, there is a CN HPLC column, NH2 HPLC column, DIOL HPLC column.
The mobile phase generally uses a nonpolar or weakly polar organic solvent having a lower polarity than the bonded phase, such as a hydrocarbon solvent, or a certain amount of a polar solvent (such as chloroform, alcohol, acetonitrile, etc.) to adjust the mobile phase. Elution intensity.
It is commonly used to separate compounds of different polarities, to separate isomers, and in particular to separate different types of compounds.
The separation mechanism of normal phase chromatography is generally considered to belong to the partition chromatography. The distribution ratio K of the component increases as the polarity thereof increases, but decreases as the polarity of the polarity modifier in the mobile phase increases (or increases in concentration). At the same time, the greater the polarity of the polar bonded phase, the greater the retention of the component.
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