Facile modification of multi-walled carbon nanotubes–polymeric ionic liquids-coated solid-phase microextraction fibers by on-fiber anion exchange

• On-fiber anion exchange was used to tune extraction properties of PILs–MWCNTs SPME fibers.
• MWCNTs were chemically bonded onto the stainless steel substrate and served as the support of PILs coating.
• Extraction performance was tested with alcohols, n-alkanes, phthalates esters, and halogenated aromatic hydrocarbons.
• Fibers showed high extraction efficiency for corresponding analytes.

In situ anion exchange has been proved to be an efficient method for facile modification of polymeric ionic liquids (PILs)-based stationary phases. In this work, an on-fiber anion exchange process was utilized to tune the extraction performance of a multi-walled carbon nanotubes (MWCNTs)-poly(1-vinyl-3-octylimidazolium bromide) (poly(VOIm+Br−))-coated solid-phase microextraction (SPME) fiber. MWCNTs were first coated onto the stainless steel wire through a layer-by-layer fabrication method and then the PILs were coated onto the MWCNTs physically. Anion of the MWCNTs–poly(VOIm+Br−) fiber was changed into bis(triflroromethanesulfonyl)imide (NTf2−) and 2-naphthalene-sulfonate (NapSO3−) by on-fiber anion exchange. Coupled to gas chromatography, the MWCNTs–poly(VOIm+Br−) fiber showed acceptable extraction efficiency for hydrophilic and hydrogen-bonding-donating alcohols, with limits of detection (LODs) in the range of 0.005–0.05 μg mL−1; after the anion exchange with NTf2−, the obtained MWCNTs–poly(VOIm+NTf2−) fiber brought wide linear ranges for hydrophobic n-alkanes with correlation coefficient (R) ranging from 0.994 to 0.997; aromatic property of the fiber was enhanced by aromatic NapSO3− anions to get sufficient extraction capacity for phthalate esters and halogenated aromatic hydrocarbons. The MWCNTs–poly(VOIm+NapSO3−) fiber was finally applied to determine several halogenated aromatic hydrocarbons in groundwater of industrial park.