Packing materials for low pressure preparative and flash chromatography. Chemically stable from pH 2 to 8,5. They are not damaged by the use of cleaning and antimicrobial agents such as sodium azide, dilute aqueous solutions of trifluoroacetic acid and acetic acid, organic solvents such as methanol and acetonitrile, and concentrated aqueous solutions of salts and urea. The packings feature irregular-shaped particles.