Influence of Phase Compositions, pH and Temperature on Bovine Serum Albumin Partitioning in Aqueous Biphasic System

The partitioning of bovine serum albumin (BSA) was investigated in polyethylene glycol (PEG) 4000-sodium citrate system at 308K and 318K with varying pHs and tie line lengths (TLL). The systems were prepared at a pH of 5.2, 7.1 and 9.2 with different TLL compositions. The affinity of the BSA for the lower phase increases with an increase in pH, which is due to an increase of trivalent to divalent citrate ions in the two phase system. The affinity of the BSA to the upper phase increases with an increase in TLL, which is due to the increase in available free volume in the upper phase. As the temperature increases, the partition coefficient of BSA shows increment.