Unbreakable solid-phase microextraction fibers obtained by sol-gel deposition on titanium wire

Solid-phase microextraction commercial fibers present a few drawbacks such as relatively low recommended operating temperature, instability and swelling in organic solvents, breakage of the fiber, stripping of coatings, and bending of the needle. Some of these problems have been obviated by covalent bonding of the polymer phase to the fused-silica substrate by sol-gel, but the easy breakage of the fiber remains a problem. In the present work, the known occurrence of titanol groups at the surface of titanium wire was exploited to produce sol-gel fibers supported on this unbreakable substrate. Scanning electron microscopy analysis revealed the film formation on titanium wire surface while temperature and solvent stability as well as durability tests showed that the sol-gel film was tightly attached to the substrate, thus suggesting covalent bonding. The use of this type of fiber is currently generalized in our laboratory without any breakage or stripping out incidents up to the moment.