Solid-phase microextraction based sol–gel technique using poly(ethylene glycol) grafted multi-walled carbon nanotubes as extracting phase

Abstract

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