Tailoring the selectivity of titania nanowire arrays grown on titanium fibers by self-assembled modification of trichlorophenylsilane for solid-phase microextraction of polycyclic aromatic hydrocarbons.

The authors describe TiO2 nanowires (TiO2NWs) for solid-phase microextraction of polycyclic aromatic hydrocarbons (PAHs). Well-oriented TiO2NWs were in-situ grown on a titanium wire by a hydrothermal process. The TiO2NWs arrays are radially aligned on the curved titanium fiber substrate. They possess a large surface area and are readily accessible for subsequent self-assembly of trichlorophenylsilane via formation of Ti-O-Si bonds. The TiO2NWs coated fibers show good extraction selectivity for PAHs as shown for phenathrene, fluoranthene, pyrene and benzo[a]pyrene. Following desoption by mobile phases for HPLC analysis, the PAHs were quantified by HPLC with UV detection. The improved extraction capabilities and good selectivity are explained by synergistic hydrophobic and π stacking interactions between the phenyl moieties and the PAHs. Key parameters that affect the extraction performance of the fibers were optimized. The method has a linear response in the 0.1 to 200 μg·L-1 PAH concentration range. Limits of detection (at S/N = 3) range from 20 to 50 ng·L-1. Relative standard deviations (RSDs) for the single fiber repeatability are less than 7.3% (n = 5) and RSDs for the fiber-to-fiber reproducibility are below 8.1% (n = 5). The method was successfully applied to the selective preconcentration and determination of trace PAHs in spiked water samples. Graphical abstract Schematic presentation of fabrication and characterization of the Ti@TiO2NWs@Phenyl fiber. PAHs: polycyclic aromatic hydrocarbons; UVFs: ultraviolet filters; PAEs: phthalate acid esters; CPs: chlorophenols.