The large-scale, economic purification of proteins is an increasinly important problem for the biopharmaceutical industry. Manufactuers of protein based pharmaceutical products must comply with strict regulatory standards, including extremely strinent purity requirements.

Hycrophobic interaction chromatography (HIC) – anion/mixed-mode/cation exchange: Defrees (US 2010/0075375 A1) discloses processes for the isolation of polypeptide conjugates using HIC in conjuction with at least one other chratography step selected from AEX, mixed mode chromatography such as hydroxyapatite or fluorapatite chromatography and CEX.