Antibodies, especially monoclonal antibodies, can be purified by Protein A, Protein G, or Protein L which binds to IgG specifically. However, when we need to purify IgM, IgE and IgA antibodies, there is no ligand to bind these immunoglobulin except the antigen which the antibodies recognize. Therefore, ammonium sulfate precipitation and ion-exchange chromatography generally are used for the purification.

Recently, monoclonal antibody production from Hybridoma is only allowed in non-animal methods, not collecting ascites. We can use a bioreactor with serum free medium instead of animal. The serum free medium contains surfactants generally to protect hybridoma (1). The surfactant may affect the antibody purification. The surfactants can be precipitated by ammonium sulfate at the same concentration for antibodies (40-50%), and bind to ion-exchange resins and eluted with similar NaCl concentration which immunoglobulin being eluted.

These issues bring contamination of surfactants in the antibody solution. In addition, some surfactants, such as Pluronic F68, have absorbance at 280nm which generally is used to determine immunoglobulin concentration (IgG 1 mg/ml, OD=1.43 at 280nm) (2).

Therefore we may need to evaluate antibody concentration using a protein assay such as BCA protein assay and a purity by a SDS-PAGE analysis.

1. K. Sakai, C. Hayashi, H. Yamaji, H. Fukuda, Use of nonionic surfactants for effective supply of phosphatidic acid in serum-free culture of Chinese hamster ovary cells. J. Biosci. Bioeng. 92, 256–261 (2001).

2. H. Ghebeh, A. Handa-Corrigan, M. Butler, Development of an assay for the measurement of the surfactant pluronic F-68 in mammalian cell culture medium. Anal. Biochem. 262, 39–44 (1998).