Standard anions in an ionic liquid (1-butyl-1-methylpyrrolidinium bis(trifluoromethane) sulfonimide).

Ionic liquids, also denominated as «designer solvents», are organic salts that are liquid at low temperatures. They are powerful solvents, conduct the electric current, and are therefore used in many applications. Anions, in particular halogenides, are common byproducts in the manufacturing of ionic liquids. Therefore, their concentration has to be controlled.