Temperature and time-controlled hydrothermal growth and sorption selectivity of titania nanowires on titanium fiber for highly efficient solid-phase microextraction.

Two kinds of TiO2 nanowires (TiO2NWs) with different orientation were in-situ grown on Ti substrates by controlling temperature and time during the hydrothermal process. The adsorption performance was evaluated by using typical aromatic compounds as model analytes coupled to HPLC with UV detection. The results demonstrated that the TiO2NWs coating grown at higher temperature within longer time had better affinity towards PAHs. For this purpose, the key experimental factors affecting the adsorption performance of the TiO2NWs coating fabricated at 200 °C for 10 h were further investigated and optimized for the extraction of PAHs. Under the optimized conditions, the proposed method presented linear responses in the concentration ranges of 0.05 to 200 µg·L-1 PAHs with correlation coefficients more than 0.998. LODs (S/N=3) were 0.008 to 0.034 µg·L-1. Moreover, RSDs for the single fiber repeatability of the intra-day and the inter-day analyses were less than 5.6% (n=5) and 5.8%, respectively. RSDs for the fiber-to-fiber reproducibility were between 5.1% and 6.5%. Finally, the proposed method was successfully applied to the selective preconcentration and determination of trace PAHs in environmental water samples. In addition, The fabricated Ti fiber can be used at least 200 times due to its high mechanical and chemical stability.