Expanded bed adsorption of albumin and immunoglobulin G from human serum onto a cation exchanger mixed mode adsorbent

Adsorption of human serum albumin (HSA) and immunoglobulin G (IgG), two most relevant proteins in blood serum were measured separately on a new mixed-mode adsorbent (MabDirect MM), especially designed for expanded bed adsorption process. Expanded bed behavior characterization by residence time distribution experiments for different columns (Streamline 50 for HSA study, Omnifit 66/20 and XK 16/20 for IgG study) are presented together with breakthrough adsorption of HSA and IgG for different conditions and compared with simulation results by a mathematical model. Regarding HSA adsorption, all four experiments were conducted at the same buffer solution (pH 5.0 without salt), and it was obtained a dynamic binding capacity of 8.9, 9.7, 7.5 and 7.0 mg·gdry−1 (24.8, 27.0, 21.0 and 19.5 mg·cm−3) at 10% of breakthrough, corresponding to a 41, 39, 38 and 30% of the saturation capacity for runs 1–4, respectively. The results from the simulation of the mathematical model fitted well with the breakthrough experiments. Elution stage was optimized by lowering flow rate and changing the buffer solution pH and NaCl concentration. Concerning IgG adsorption, for IgG feed concentration of 0.53 g·dm−3 in 20 mM citrate buffer, pH 5.0 with 0.4 M NaCl, at 2.2 cm3·min−1, it was obtained a DBC of 3.3 mg·gdry−1 (9.1 mg·cm−3) at 10% of breakthrough, representing 22% of the saturation capacity. While for a feed concentration of 0.11 g·dm−3 of IgG in the same buffer solution, at 6 cm3·min−1, it was obtained a DBC of 2.7 mg·gdry−1 (7.4 mg·cm−3) at 10% of breakthrough, representing 34% of the saturation capacity.