Exploiting the Versatility of Ionic Liquids in Separation Science: Determination of Low-Volatility Aliphatic Hydrocarbons and Fatty Acid Methyl Esters Using Headspace Solid-Phase Microextraction Coupled to Gas Chromatography

Abstract

The determination of high-molecular weight aliphatic hydrocarbons and fatty acid methyl esters possessing high boiling points and low vapor pressures was performed using a headspace solid-phase microextraction gas chromatography (HS-SPME-GC) method comprised entirely of ionic liquids (ILs). The method utilizes three independently structurally engineered ILs in which the imparted physical and chemical properties make them compatible with the requirements of each component of the method. Component one is composed of a thermally stable IL solvent used to increase the equilibrium concentration of analytes in the HS, component two is a SPME sorbent coating based on a polymeric ionic liquid (PIL) for the selective HS extraction of analytes, and component three is an IL-based low-bleed GC stationary phase that performs the selective separation of the analytes. The method demonstrates the versatility of ILs within separation science in addition to determining these analytes, for the first time, using HS extraction at elevated temperatures with detection limits ranging from 0.3 to 0.6 mg kg(-1), relative recoveries from 69.9% to 106%, and precision (relative standard deviation for the overall method) from 6.9% to 16%.