The present application provides methods of purifying Aβ binding proteins having a Fc region, for example, anti-Aβ antibodies or antibody fusions, by adsorbing the Aβ binding protein to a Fc binding agent, such as, for example, Protein A or Protein G, followed by a wash with a divalent cation salt buffer to remove impurities and subsequent recovery of the adsorbed Aβ binding protein. The present application also features methods of eluting the purified Aβ binding protein as well as the incorporation of the methods within a purification train. Kits comprising components for carrying out the methods and instructions for use are also provided.