Chromatography of hydrophobic interactions (HIC) separates and purifies biomolecules based on differences in their hydrophobicity. The absorbent phenyl membrane follows the same rules known from conventional hydrophobic interaction chromatography. Due to the large pore size, the absorbent membrane shows excellent flow properties. There is almost no diffusion limitation of mass transport compared to conventional bead chromatography. Buffers with a high salt concentration promote protein adsorption on the matrix of the hydrophobic membrane. Proteins are eluted by reducing the salt concentration in the wash buffer.
HIC is an excellent method for distinguishing between target proteins and hydrophobic contaminants. Large proteins bind more strongly than small ones, and aggregates are even significantly better than monomers due to multipoint binding. A high ionic strength buffer, usually ammonium sulfate, is initially added to the protein solution. Salt ions in this solution reduce the dissolution of solutes in the sample. As dissolution decreases, the hydrophobic areas that become exposed are adsorbed by the hydrophobic membrane matrix. In HIC membrane, flexible cellulose is used as a substrate for phenyl ligand. The membrane can be regenerated using water or alcohol.