Solid-phase microextraction Ni–Ti fibers coated with functionalised silica particles immobilized in a sol–gel matrix

One of the possible approaches for the development of novel solid-phase microextraction (SPME) fibers is the physical deposition of porous materials onto a support using high-temperature epoxy glue. However, a major drawback arises from decomposition of epoxy glue at temperatures below 300 °C and instability in some organic solvents. This limitation motivated us to explore the possibility of replacing the epoxy glue with a sol–gel film, thermally more stable and resistant to organic solvents. We found that functionalised silica particles could be successfully attached to a robust Ni–Ti wire by using a UV-curable sol–gel film. The particles were found to be more important than the sol–gel layer during the microextraction process, as shown by competitive extraction trials and by the different extraction profiles observed with differently functionalised particles. If a quality control microscopic-check aiming at the rejection of fibers exhibiting unacceptably low particle load was conducted, acceptable (6–14%) reproducibility of preparation of C18-silica fibers was observed, and a strong indication of the durability of the fibers was also obtained. A cyclohexyldiol-silica fiber was used, as a simple example of applicability, for the successful determination of benzaldehyde, acetophenone and dimethylphenol at trace level in spiked tap water. Recoveries: 95–109%; limits of detection: 2–7 μg/L; no competition effects within the studied range (≤125 μg/L).