Reverse phase chromatography polymer based

The growing popularity of reversed phase chromatography in particular has prompted polymer manufacturers to investigate the use of polymeric media for this mode of operation. Macroporous copolymers of styrene and divinylbenzene have similar properties to silica based stationary phases bonded with alkyl chains. However, the absence of leachables and stability at high pH can offer advantages under certain circumstances. High quality, mechanically stable macroporous polymeries are now manufactured at much larger scales than the... 

A common characteristic of all polystyrene/divinylbenzene-based ion-exclusion phases is the high retention of aromatic carboxylic acids. This is due to 7t-7t interactions between the aromatic ring systems of the polymer and the solute. The separation of aromatic carboxylic acids, therefore, is more elegantly accomplished by the various procedures of reversed-phase chromatography. 

If the analytes are ionic or ionizable, they can be separated by ion-exchange, ion-pairing, or reversed-phase chromatography. Both polymeric and silica-based ion exchangers are available. Silica-based ion exchangers exhibit better efficiency than polymer-based ion exchangers, but can not be used at basic pH values. Silica itself is a cation exchanger of excellent efficiency and can be used for the analysis of basic sample compounds. For a detailed discussion, see Chapter 12. 

Silica gels are used in gel permeation chromatography, based on size exclusion of polymers from the pores. Silica gels have also found use as a polar column sorbent. Modification of the silica by silanes makes the stationary phase apolar. Because most interactions are reversed, compared with the pure silica, separations using these apolar columns are termed reversed-phase chromatography . 

The last two examples show that, in a number of cases, cation-exchange chromatography can be regarded as an alternative to reversed-phase chromatography on chemically bonded silica phases, especially because the characteristic interactions between the basic compounds and the free silanol groups of silica are not observed with polymer-based cation exchangers. 

Reversed-phase chromatography is a separation method based on the hydrophobicity of the protein. In RPC, the hydrophobic stationary phase is based on silica gel or a synthetic polymer. In recent years, instead of bulk materials for column packing, polymer- or silica gel-based monolithic stationary phases have also been used [43]. 

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