Salt effects on the retention of peptides in hydrophobic interaction chromatography

This study investigated the effects of salt in a SynChropak column using peptides which are structurally simpler than proteins. Contrary to the established explanation of salt type by molal surface tension increment, the study attempted to explain salt effects by two retention parameters, S and log k(w). S was considered to be related to surface tension effect, log k(w) to salting in effect. From the dependence of S and log k(w) on temperature and the stationary phase ligand type, these parameters turned out to be useful in explaining the characteristics of hydrophobic interaction chromatography (HIC) which are different from those of reversed phase chromatography (RPC). We examined enthalpy-entropy compensation because of the similar tendency of enthalpic and entropic values in the retention process. The uses and characteristics of five different salts were also discussed.