Determination of Ethanol in Ionic Liquids Using Headspace Solid Phase Microextraction - Gas Chromatography

Ionic liquids (ILs) being non volatile, non-flammable, recyclable and designer friendly, are gaining wide recognition as green solvents and efficient reaction media in process industries as potential replacements for volatile organic solvents. The application of ionic liquids as non-derivitizing solvents for the pretreatment and regeneration of cellulosic and hemicellulosic biomass for the production of biofuels is a growing area of research. Commercial viability materializes when the reaction media / green solvent is completely recovered and recycled in any processing stream. Anti-solvents such as water or ethanol are employed in the recovery process and it is of interest to quantify volatile components such as ethanol in the IL-water mix. This study reports the development of a rapid and simple method for the determination of residual ethanol content in ionic liquids. The method utilizes headspace solid phase microextraction (SPME) coupled to gas chromatography using elevated extraction temperatures resulting in rapid equilibration times. The effect of IL water content on the ethanol extraction efficiency is presented. Recovery experiments carried out in real samples gave recoveries ranging from 96.8 to 98.2%.