Gas Chromatography Columns Using Ionic Liquids as Stationary Phase

Abstract

Ionic liquids satisfy the requirements of a gas chromatography stationary phase, among which characteristics include high viscosity, tunable selectivity through structural modifications, good wettability with respect to fused silica capillaries, and high thermal stability. When incorporated in either the first or second dimension of multidimensional gas chromatography, they offer unique selectivity compared to conventional gas chromatography stationary phases. The utilization of commercial ionic liquid columns for analysis of various analytes (i.e., fatty acids, flavors and fragrances, organic pollutants, and petrochemical samples) in complex matrices is described in this chapter. Thanks to their dual-nature behavior, IL-based stationary phases provide unique separation for both polar and nonpolar molecules in complex samples, such as essential oils. Moderately polar phosphonium-based ionic liquid columns (i.e., SLB-IL59, SLB-IL60, and SLB-IL61) with high operating temperature are suitable for analysis of complex petrochemical and environmental samples. The high polarity of ionic liquid columns allows analysis of positional isomers including those of unsaturated fatty acids. The other exceptional feature of ionic liquid columns is their stability in the presence of water and oxygen at high temperatures. Water-compatible ionic liquid-based gas chromatography capillary columns facilitate the direct injection of aqueous samples without the requirement of time-consuming sample pretreatment techniques.