Purolite A400 is an industrial grade, polystyrenic gel, Type I strong base anion exchange resin that is typically supplied in the chloride (exhausted) form. It is also available in the hydroxide (regenerated) form as Purolite A400OH. The data in this engineering bulletin is specific to Purolite A400 supplied in the chloride form with information and engineering data on the removal of anions as part of the demineralization process. The principal application of Purolite A400 is in water demineralization.