Polysorbate 20 is typically used as an emulsifying agent for the preparation of stable oil-in-water emulsions, particularly in pharmaceutical applications. It has been used in pre-extraction of membranes to remove peripheral proteins. It has been used as a blocking agent on nitrocellulose.
Tweens® are a series of nonionic surfactants derived from sorbitan esters. They are soluble or dispersible in water but differ widely in organic and oil solubilities. Used as oil-in-water emulsifiers in pharmaceuticals, cosmetics, cleaning compounds, etc.