Development of octadecyl-functionalized-nanotubular TiO2/Ti wire solid-phase microextraction fiber

An octadecyl-functionalized solid-phase microextraction (SPME) fiber was prepared by sol–gel technology with an anodized Ti wire as the substrate and dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (C18-TMS) and tetraethoxysilane (TEOS) as sol–gel precursors. The anodized Ti wire has high mechanical strength and has numerous titanol groups on its surface for sol–gel reactions, consequently offering better performances than the commercial fragile fused silica substrate. The C18-TMS/TEOS sol–gel coated fiber has good thermal stability and stability against organic solvents. There is no loss in the performance after 100 cycles of exposure to acetonitrile and high temperature (300 °C) in turn. The developed fiber with a very thin (ca. 2 μm) coating thickness exhibits comparable or even superior extraction capability relative to the commercial 100 μm polydimethylsiloxane (PDMS) fiber. Under optimized conditions, the detection limits for the polycyclic aromatic hydrocarbons are in the range of 0.003 to 0.025 μg L−1 with a linear range from 0.01 to 20 μg L−1. The proposed method was successfully applied in the analysis of environmental water samples with the recoveries ranging from 85.3 to 101.8%.