Polyaniline/titanium dioxide nanorods functionalized carbon fibers for in-tube solid-phase microextraction of phthalate esters prior to high performance liquid chromatography-diode array detection

To improve extraction performance of carbon fibers (CFs) towards phthalate esters (PAEs), titanium dioxide (TiO 2 ) nanorods array was in-situ grown on the surface of CFs, then polyaniline (PANI) was used to modify it. PANI/TiO 2 nanorods-CFs were placed into a polyetheretherketone tube for solid-phase microextraction (SPME). Combining the tube to high performance liquid chromatography (HPLC), it was evaluated and displayed good extraction performance for several PAEs. Compared with bare CFs, TiO 2 nanorods and PANI, PANI/TiO 2 nanorods presented best performance, attributed to the unique advantages between high surface area of TiO 2 nanorods and multiple adsorption interactions (like π-π stacking, hydrogen bond ) of PANI. After the optimization of the important factors (sampling volume, sampling rate, sample pH, concentrations of organic solvent and salt in sample, and desorption time), the online in-tube SPME-HPLC method was established. It provided low limits of detection (0.01-0.05 μg L −1 ) and wide linear ranges (0.03-30, 0.10-30, 0.17-30 μg L −1 ) with correlation coefficients larger than 0.9991. The relative standard deviations (n=6) between intra-day and inter-day tests were in the ranges of 3.5-10.3% and 4.7-13.9%, respectively. The method was successfully used to determine seven PAEs in real water samples. Besides of satisfactory durability, the material also exhibited superior extraction performance than some materials.