Principle of forward high performance liquid chromatography?

Principle of forward high performance liquid chromatography? Reversed phase high performance liquid chromatography, normal phase partition chromatography, relationship and difference between reverse phase partition chromatography?
answer:

Chromatographic column packing can be directly composed of matrix, such as silica gel, alumina, styrene divinylbenzene with high cross-linking degree or methacrylate, etc.; it can also be coated on the basis of these matrices or chemically bonded stationary liquid, such as the most classic ODS column, amino column, cyano column, etc
Silica gel retains polar molecules mainly through the polar silanol groups on the surface, which belongs to the normal phase separation mode. Through silylation technology, functional groups with different properties can be built on the surface of silica gel, such as octadecyl (ODS), octadecyl, methyl and phenyl, which can increase the retention of non-polar molecules, The results showed that the structure of reversed phase chromatography was reversed phase chromatography; silane with diol group, amino group, cyano group and other polar groups was bonded to improve the retention of some polar molecules to form normal phase or reverse phase chromatography; the bonding phase with ether group formed normal phase or reverse phase chromatography with medium polarity; the bonded phase with strong acid sulfonic acid type or strong basic quaternary ammonium salt type was used to form ion exchange chromatography
Normal phase chromatography is the classical form of chromatography, using polar stationary phase and non-polar mobile phase. The eluent is retained by the interaction between its polar group and the polar group on the stationary phase. In this application, the classical method is to use unbound silica gel and alumina, but the polar bonded phase has the following advantages: the bonding phase is fast in equilibrium, and is insensitive to trace water in the mobile phase, Compared with pure silica gel, diol bonded silica gel has smaller polarity and faster equilibrium speed; cyano bonded phase is the normal phase adsorbent with minimum retention capacity; amino bonded phase is suitable for the separation of aromatic hydrocarbons
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