A liquid chromatography agglomerated bed comprising component A comprising (a) substrate particles and polymer chains (e.g. a condensation polymer) bound to the substrate particles and projecting therefrom, and (b) component B comprising substrate particles having external surfaces of opposite charge to that of the charged polymer chains, components A and B being bound at least in part by electrostatic forces between the component A charged polymer chains and the component B external surfaces to form in composite an agglomerated bed of ion exchange particles packed in a chromatography column.