Polymeric ionic liquids as selective coatings for the extraction of esters using solid-phase microextraction

A new class of stationary phase coatings for solid-phase microextraction (SPME) based on polymeric ionic liquids (PILs) is presented. PIL-based SPME coatings exhibit exceptional film stability, high thermal stability, reproducible extraction efficiencies, and long lifetimes. A series of three homologous polymeric imidazolium-based ionic liquid coatings were synthesized by free radical reaction. The fiber coatings were used to extract esters and fatty acid methyl esters from aqueous solution followed by gas chromatographic separation and flame ionization detection. To examine the effect of the matrix on the coatings, extractions were carried out in a synthetic wine solution followed by recovery experiments in two real wine samples. When carrying out the extractions in aqueous solution, the detection limits for most analytes ranged from 2.5 to 50 μg L−1 whereas lower detection limits were obtained for larger fatty acid methyl esters. Recovery experiments carried out in red and white wines ranged from 70.2% to 115.1% using the PIL fibers compared to 61.9% to 102.9% using a commercial polydimethylsiloxane fiber of similar film thickness. The structural tuning capability of these new coating materials makes them widely amendable to performing task-specific microextractions.