Purification of human IgG using membrane based hybrid bioseparation technique and its variants: A comparative study

This paper compares three different techniques for IgG purification from human serum, all of which are based on a recently developed membrane based hybrid bioseparation strategy, i.e. combination of salt induced precipitation, microfiltration and membrane adsorption as one unit operation [R. Ghosh, Separation of human albumin and IgG by a membrane-based integrated bioseparation technique involving simultaneous precipitation, microfiltration and membrane adsorption, J. Membr. Sci. 237 (2004) 109–117]. When used on its own, the standard hybrid bioseparation technique gave 93% recovery of IgG from human serum with 85% purity. In order to obtain higher IgG purity, caprylic acid based precipitation was investigated as a second purification step. As an alternative approach to this, caprylic acid precipitation was integrated with the standard hybrid bioseparation technique, resulting in a single step process. The antibody obtained using the three above mentioned techniques were then diafiltered to remove salts and caprylic acid and the overall purity and recovery were compared. The integrated hybrid–caprylic acid purification technique gave the highest IgG purity (95%) with the recovery being 55% while the purity and recovery using the two-step approach were 93% and 73% respectively. The trade off between purity, recovery and membrane fouling are discussed.