CHEMICAL RAW MATERIALS FOR IN VITRO USE, NAMELY MONODISPERSE POLYMER PARTICLES MADE FROM POLYSTYRENE, POLYVINYL CHLORIDE, POLYDIVINYLBENZENE, POLYACRYLATES, AND VARIOUS COPOLYMERS FOR USE AS REGAENTS, SEPARATION AGENTS, CARRIERS, EXCHANGE RESINS, MATTING AGENTS AND CHROMOTOGRAPHY MEDIA