In this study, poly(ethylene glycol) (PEG) grafted onto multi-walled carbon nanotubes (PEG-g-MWCNTs) were synthesized by the covalent functionalization of MWCNTs with hydroxyl-terminated PEG chains. For the first time, functionalized product of PEG-g-MWCNTs was used as selective extraction phase to prepare the sol–gel solid-phase microextraction (SPME) fiber in combination with gas chromatography-flame ionization detector (GC– FID) for the determination of ultra-trace levels of BTEX compounds, MTBE and non-steroidal anti-inflammatory drugs in real samples. The PEG-g- MWCNTs were characterized by Fourier transform infrared spectra and also thermo-gravimetric analysis, which verified that PEG chains were grafted onto the surface of the MWCNTs. The scanning electron micrographs of the fiber surface revealed a highly porous structure which greatly increases the surface area for PEG-g-MWCNTs sol–gel coating. This fiber demonstrated many inherent advantages, the main being the strong anchoring of the coating to the fused silica resulting from chemical bonding with the silanol groups on the fused-silica fiber surface. The new PEG-g-MWCNTs sol–gel fiber is simple to prepare, robust, with high thermal stability and long lifetime. Important parameters influencing the extraction efficiency such as desorption temperature and time, extraction temperature, extraction time, pH, stirring speed and salt effect were investigated and optimized.

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