The simple and commonly adopted batch process involves the mixing of reagents together in a suitable buffer solution, preferably at a temperature between 4 and 6 �C, followed by the separation and purification of the desired product using a suitable technique based on its physicochemical properties, including size exclusion chromatography ( SEC ), ion exchange chromatography ( IEX ), hydrophobic interaction chromatography ( HIC ) and membranes or aqueous two phase systems.