Ionic liquids (ILs) are a class of molten salts with melting points considerably lower than conventional inorganic salts. Their unique properties make them an ideal class of separation media for various sample preparation techniques. Polymeric ionic liquids (PILs) inherit many physical properties of ILs such as high thermal stability, negligible vapor pressure, multiple solvation interactions and can easily be chemically modified to tether a variety of functional groups. In addition, PILs possess high viscosity making them amenable to forming stable, thin films on the fused silica glass fibers, a requirement of solid-phase microextraction (SPME). SPME is a high speed sample preparation technique possessing a number of advantages such as simplicity, and no organic solvent requirement. The marriage of PILs with SPME opens a new avenue in the search for new sorbent coatings. This dissertation is dedicated towards the design and synthesis of PILs and employs them as SPME sorbent coatings coupled with gas chromatography (GC).
The dissertation begins with the definition of ILs. The applications of ILs in a number of sample preparation techniques are introduced. The following chapters describe the synthesis of various PILs and their application as SPME sorbent coatings for the extraction of various analytes. PILs including poly(1-vinyl-3-hexadecylimidazolium) bis[(trifluoromethyl)sulfonyl]imide (poly([ViHDIm] [NTf2])), poly(1-(4-vinylbenzyl)-3-hexadecylimidazolium bis[(trifluoromethyl)sulfonyl]imide) (poly(VBHDIm+ NTf2-)), and poly(1-vinyl-3-hexylimidazolium chloride) (poly(ViHIm+Cl-)) were synthesized.
The poly([ViHDIm] [NTf2]) PIL provides stable SPME coatings for both headspace-SPME or direct-immersion SPME, and can be used at elevated temperature conditions to perform extractions. The poly(VBHDIm+ NTf2-) PIL exhibited high affinity towards analytes bearing aromatic groups due to the presence of benzyl-functional moieties in the PIL structure. The poly(ViHIm+Cl-) PIL demonstrated high selectivity towards polar analytes with high hydrogen bond acidity, due to the high hydrogen bond basicity of the Cl- anion in the PIL structure.