Abstract: A method of separating organic materials is disclosed utilizing a chromatographic packing material. This packing material includes a coated support material which is a chromatographically suitable substrate. An immobilized butadiene acrylonitrile polymer coating is provided on the substrate. The copolymer can be crosslinked by gamma radiation, or by means of a crosslinking agent such as dicumyl peroxide. The support material can be silica, alumina, diatomaceous earth, zeolite, porous glass or carbon, but preferably a spherical lamellar shaped crystals of aluminum hydroxide. the aluminum hydroxide crystals are bonded together at a central core and extend radially outward from a central core with a particle density ranging from 0.3 to 2.5 g/cm.sup.3 and a diameter of 2 to 150 microns.