The amino acid ortho-phosphoserine (OPS) is a feasible alternative to expensive protein ligands for the purification of IgG due to its selectivity, elution under non-denaturing conditions, and low cost. In this study we investigated the adsorption of IgG(2a) mouse monoclonal antibody (MAb) from precipitate solution of hybridoma culture supernatant onto OPS-agarose adsorbent. The effects of spacer arm, buffer system, pH, and NaCl concentration on the adsorption of IgG2a MAb were evaluated. Screening buffer systems showed that Tris-HCl at pH 7.0 provided the highest IgG(2a) MAb yield (77%) and purification factor (31.8). The adsorption of IgG(2a) MAb was observed to decrease by approximately 90% as the NaCl concentration was increased from 0.0 to 100 mmol L-1. A kinetic study of IgG(2a) MAb adsorption showed that these data were in agreement with the pseudo-first-order kinetic model. This study suggests the potential for use of OPS-agarose in the purification of IgG(2a) MAb from hybridoma culture supernatants. (C) 2015 Elsevier Ltd. All rights reserved.