the extraction or purification of biomaterials and other products by liquid - liquid extraction in an aqueous system is enhanced by introducing a particulate polymeric adsorbent into the extraction system and agitating the system , whereupon the adsorbent reversibly binds the product or material to be separated from the product , to form a complex , and the complex preferentially partitions into one of the liquid phases . the complex is then separated , and the product recovered from the complex or the remaining liquid . ion exchange resins comprising beads or ground particles , of 0 . 01 - 10 micrometer average diameter , are representative adsorbents .