Simultaneous correlation of hydrophobic interactions in HIC and protein solubility in aqueous salt solutions and mixed solvents

Combined effects of potassium chloride and ethanol as mobile phase modulators on hydrophobic interaction and reversed-phase chromatography of three insulin variants

“…This has been shown for lysozyme on seven different HIC adsorbents in a previous study [13]. However, it was not found in the present study, as each series had a different slope.…”

“…The final model is a function of the ionic strength and pH of the mobile phase. In a later study [13], Mollerup et al presented a modified version of the model, assuming that changes in mobile phase composition only affect the activity coefficient of the solute when it is in solution and in the adsorbed state. The modulator effects are described by Kirkwood's theory of salting-in and salting-out of macromolecules.…”

“…Nonetheless, the hydrophobic interactions between solute and ligand in both HIC and RPC can be manipulated by salts as well as organic solvents. However, few studies have been carried out on the effect of alcohols on HIC [10][11][12][13], and of inorganic salts on RPC [14,15], and those that have been performed were either focused on a certain separation problem [10,11,15], or on phenomena other than retention, such as protein unfolding during chromatography [14], or peak shape and carryover [12].…”

“…The nature of the hydrophobic phenomena in HIC and RPC, and the effects of mobile phase modulators are still being debated, despite many proposed explanations [13,[16][17][18][19][20][21][22][23]. Further investigations are therefore required to elucidate the mechanisms, and the similarities between the two modes suggest that a possible route toward a better understanding of HIC and RPC is to treat them as two sides of the same coin.…”

Modeling the permittivity of electrolyte solutions

“…The chemical potential of the complex ion in solution comprises the Born potential, a potential due to the mutual interactions of the ions similar to but not identical with the Debye–Hückel potential, and a potential caused by the interaction between the dipole of the macro ion and the simple ions in solution . Kirkwood's model has been utilized to calculate the chromatographic adsorption equilibria of Lysozyme in hydrophobic interaction chromatography . Because of the high electric field inside the complex ion, the relative permittivity inside the ion, ε sat , is less than the permittivity of the bulk solution.…”