A method for purifying a protein comprising an antibody, antibody fragment, or immunoglobulin single variable domain, from a solution containing at least one contaminant by superantigen chromatography comprising: a) adsorbing the protein to the superantigen immobilized on a solid support; b) removing the at least one contaminant by contacting the immobilized superantigen containing the adsorbed protein with a first wash buffer comprising an aliphatic carboxylate; and c) eluting the protein from the superantigen immobilized on the solid support.