Separation of human serum albumin and polyethylene glycol by electro-ultrafiltration

For the purpose of residual PEG removal after protein purification and PEGylation, electro-ultrafiltration (EUF) was used for separation of human serum albumin (HSA) from polyethylene glycol (PEG) with different molecular weights. The results clearly demonstrated the effectiveness of EUF for achieving the desired objectives. Higher flux and lower HSA transmission were observed in EUF process with the feed consisting of a mixture of 1 g/L PEG and 1 g/L HSA, compared to conventional ultrafiltration (UF) process, while the PEG transmission was nearly the same. When the concentration of PEG increased from 1 g/L to 10 g/L while keeping the HSA concentration the same, more HSA passed through the membrane in the UF process due to reduction in protein diffusion and hydration by PEG. When the HSA concentration increased from 1 g/L to 10 g/L with the PEG concentration being 1 g/L, the PEG transmission decreased significantly. The application of electric field resulted in high flux and PEG transmission and low protein transmission through the membrane. The effect of electrolyte (i.e., ionic strength and type) on the efficiency of the EUF process was also investigated.