Numerical analysis of the liquid-liquid phase separation in the antibody–human serum albumin mixtures in aqueous buffer solution

•Numerical analysis of the phase behavior of the antibody-human serum albumin mixtures is carried out.•Properties of the system are governed by the antibody-human serum albumin attraction.•Calculated tie-lines indicate an accumulation of HSA molecules in the concentrated Ig phase.•The temperature of the phase separation almost linearly decreases with concentration of added HSA.•With the increase of the concentration of HSA the mixture is stabilized.