Salt Types and Additives in Multimodal Chromatography Media

Extracted from Multimodal Chromatography (PDF), GE Healthcare, 2013

Different salt types and additives can modulate the interactions of target molecule with multimodal chromatography media. Because hydrophobic interaction is one of the interaction modes that is often involved, the choice of salt may play an important role.

Different salt types will affect the strength of interaction according to the Hofmeister series (Fig 2.7). Typical ions used in HIC are found to the left in the series, while the chaotropic ions to the right in the series, for example, iodine, reduce the hydrophobic interaction through the salting-out effect.

Structure of a recombinant DAb

Fig 2.7. Hofmeister series.

Organic solvents, for example, ethanol and isopropyl alcohol, decrease the strength of hydrophobic interactions and can, as such, affect the binding of biomolecules to multimodal chromatography media. Detergents and antifoaming agents such as Tween™ 80 and Triton™ X-100 can have a similar effect.

Hydrogen bond disruptors such as urea and guanidine hydrochloride also have the potential to impact the strength of interaction on multimodal chromatography media. Some compounds might influence several different interactions, for example, urea and guanidinium salt are chaotropic as well as hydrogen bond disruptors. Studies on several other modifers, for example, amino acids or polyethylene glycol, have also been published. Examples of the influence of salt types and additives for Capto adhere and Capto MMC are found in Chapter 3.

Materials

     
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