Chromatography charge-transfer adsorption

New stationary phases for specific purposes in chromatographic separation are being continually proposed. Charge transfer adsorption chromatography makes use of a stationary phase which contains immobilised aromatic compounds and permits the separation of aromatic compounds by virtue of the ability to form charge transfer complexes (sometimes coloured) with the stationary phase. The separation is caused by the differences in stability of these complexes (Porath and Dahlgren-Caldwell J Chromatogr 133 180 1977). 

Charge transfer adsorption chromatography makes use of a stationary phase which contains immobilised... 

Figure 8.2 Variants of affinity chromatography, (a) biospecific AC (b) metal chelate chrom. (c) charge transfer adsorption chrom. (d) hydrophobic interaction chrom. and (e) covalent chrom. (chemisorption). Abbreviations E = enzyme, L = amino acid group, me = meted ion, Rw = electron - withdrawing substituent, Rr = electron -donating substituent taken from ref. (47) with permission.

Adsorption chromatography or liquid-solid chromatography (ESC) is the most frequently applied LC mode. Here, specific interactions occur among the solute, the stationary phase, and the mobile phase. Examples are hydrophobic, dipole -dipole, hydrogen bond, charge-transfer, and n-n interactions. 

ADSORPTION. The attraction between the surface atoms of a solid and an external molecule by intermolecular forces such as hydrogen bonds, London forces, electrostatic forces, and charge-transfer forces. The adsorbent is the stationary phase for adsorption TLC. Adsorption chromatography involves separation of substances, based on their polarity, in a solid-liquid system involving competing interaction between adsorption on the surface and dissolving in the mobile phase. 

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