Tuning the extraction properties of ionogel-coated Solid-phase microextraction fibers based on the solvation properties of the ionic liquids

Abstract

A silica-based network was used to immobilize ionic liquid-based ionogels and applied as a fiber coating for solid-phase microextraction (SPME). The ionogels were prepared by a sol–gel process, using two ionic liquids, triethylsulfonium bis(trifluoromethylsulfonyl)imide ([Set3][TFSI]) and 1-butyl-1-methylpiperidinium bis(trifluoromethylsulfonyl)imide ([C4C1Pip][TFSI]), as well as their equimolar mixture. Methyltrimethoxysilane was used as the sol–gel precursor, and trifluoroacetic acid as a reaction catalyst.The fabricated ionogel fibers were evaluated as sorbent coating in headspace SPME combined with gas chromatography with barrier ionization discharge detection for volatile organic compounds (VOCs). The fibers showed a high affinity to aromatic VOCs, yielding good sensitivity and precision. Then, the developed method was applied to the analysis of aqueous samples.During the study, the main extraction parameters, i.e., salt concentration, extraction time, and temperature, were optimized for maximum fiber sorption and to maximize the enrichment factors. The average limits of detection were found to be 0.15 μgL−1, 0.40 μgL−1, and 0.07 μgL−1, and the enrichment factors were in the 25700–61000, 33200–84700, and 29100–96500 ranges for [Set3], [C4C1Pip] and [Set3/C4C1Pip], respectively. The single fiber and fiber-to-fiber reproducibilities were below 11.2% and 30.6%, respectively. The results of this work suggest the possibility of fabricating selected extractants based on the physicochemical properties of the ionic liquids and target analytes.