Headspace Single Drop Microextraction Using Micellar Ionic Liquid Extraction Solvents

A headspace single drop microextraction (SDME) method using extraction solvents comprised of micellar ionic liquids (ILs) was used to perform the extraction of 17 aromatic compounds from aqueous solution and coupled with liquid chromatography. The effects of various experimental parameters including type of micellar IL extraction solvent, stir rate, extraction time, volume of the microdroplet, and addition of organic solvent were investigated and optimized. Two different micellar solutions were formed by dissolving 1-decyl-3-methylimidazolium bromide ([DMIM][Br]) and sodium dodecyl sulfate (SDS) in 1-butyl-3-methylimidazolium chloride ([BMIM][Cl]). It was observed that the enrichment factors of the 17 studied compounds were all enhanced with the micellar ionic liquid extraction solvent compared to the neat [BMIM][Cl] IL. The highest sensitivity was obtained with the [BMIM][Cl]–[DMIM][Br] micellar solution for polycyclic aromatic hydrocarbons (PAHs) with high molecular weight and fused rings while the [BMIM][Cl]–SDS micellar solution was proven to be more sensitive for smaller, more polar molecules. The detection limits were lower when utilizing the [BMIM][Cl]–SDS and [BMIM][Cl]–[DMIM][Br] extraction solvents compared to the neat [BMIM][Cl] extraction solvent. The reproducibility of the extraction method at 20 °C using extraction solvents composed of [BMIM][Cl]–SDS and [BMIM][Cl]–[DMIM][Br] ranged from 6.7 to 14.0 and 4.2 to 14.7%, respectively.