Phosphonium Ionic Liquids as Stationary Phases in Gas Chromatography

Abstract

Abstract As a relatively new material, ionic liquids (ILs) have attracted increasing attention in recent years because of their unique properties and potential applications in many fields. In this study, a phosphonium-based IL (tetra-butyl phosphonium methanesulfonate), which possessed high thermal stability and large viscosity, was systematically investigated as a stationary phase for gas chromatography. The IL column was prepared by the static coating method and the chromatographic properties, polarity, and retention character of the column were studied. The column efficiency was tested using tetradecane at 120 °C. The column provided an efficiency of 1381 plates per meter and an average polarity of 559.6 that was comparable to the polarity of the commercial PEG20M and FFAP (polyethylene glycol treated with nitro-terephthalic acid). Experimental results showed that the IL column demonstrated strong interaction with the molecules with strong proton donor groups. Both the retention factor and the selectivity for the meta and para isomers of many aromatic compounds were larger on the IL column than on the PEG20M. In addition, symmetrical peak shapes and unique separation selectivities were obtained when the IL column was used to separate the mixtures of a series of alkanes, polycyclic aromatic hydrocarbons, chlorinated benzenes, alcohols, etc.