FIGURE 4.

Reduction rates of impurities in each steps of improved method. Reductions of protein and nucleic acid contaminants are indicated by circle and square dots, respectively. Microfiltration is a filtering process using 0.2 μm cut-off capsule filter while UF/DF process is a process to remove low molecular contaminants using 50 kDa cut-off filter. PS and impurity precipitation were carried out by using CTAB and ethanol, respectively. Hydroxyapatite (HA) column was used in chromatography process and buffer exchange to the final formulation was performed in final UF/DF process.