Evaluation of a chitosan membrane for removal of endotoxin from human IgG solutions

Cross-linked chitosan membranes – prepared with silica particles as porogen agent – were evaluated for the removal of endotoxin (ET) from human immunoglobulin G (IgG) preparations. The effects of solution conditions on the efficiency of ET removal and IgG recovery were studied. The depyrogenation studies were performed with Tris–HCl at pH 7.0 due to low IgG adsorption and significant degree of protonation (0.50) of the membrane in this buffer. Adsorption ET data were analyzed using the Langmuir model (maximum binding capacity and dissociation constant were 280 μg/mL and 4.0 × 10−11 mol/L, respectively). A high ET clearance (96%) and IgG recovery (99%) were obtained with ET and IgG initial concentration of 116.4 EU/mL and 1.0 mg/mL, respectively. Therefore, these results assure the potential of using chitosan membrane filtration for ET removal in the downstream processing of IgG solutions.