Not more than 1.0 gram of particulate will dissolve in 100 gram of aqueous media or elution solvent into which particulate is mixed at 20??? C. The particulate material can be at least one of an organic compound, a polymer, or an inorganic oxide such as silica, alumina, titania, zirconia, and other ceramics, and combinations thereof, or it can be ion exchange or chelating particles or mixtures the