How Should Ionic Liquids be Analyzed?

Room-temperature ionic liquids (RTILs) salts with melting points below 100 °C have been intensively studied in recent years. Their unique properties make RTILs efficient alternatives to volatile organic solvents as environmentally benign media in many industrially important chemical processes. ILs will soon be produced on an industrial scale and it will be necessary to develop reliable analytical procedures for their analysis and control. Nowadays, reversed-phase liquid chromatography (RPLC) is widely used for separations of various imidazolium cations on alkyl-bonded stationary phases, phenyl-bonded stationary phases or on silica packing functionalized with mixed polar and apolar functions. Ion chromatography (IC), ion-pair chromatography, capillary electrophoresis and isotachophoresis are also being developed. The primary aim of this review is to outline current developments in chromatographic and electrophoretic methods applied to the analysis of routinely used ionic liquid cations and anions.