pH-resistant titania hybrid organic–inorganic sol–gel coating for solid-phase microextraction of polar compounds

A novel titania-hydroxy-terminated silicone oil (titania-OH-TSO) sol–gel coating was developed for solid-phase microextraction of polar compounds. In general, titania-based sol–gel reaction is very fast and need to be decelerated by the use of suitable chelating agents. But in the present work, a judiciously designed sol solution ingredients was used to create the titania-OH-TSO coating without the addition of any chelating agent, which simplified the sol–gel procedure. Thanks to the variety of titania's adsorption sites and their acid–base characteristics, aromatic amines, phenols and polycyclic aromatic hydrocarbons were efficiently extracted and preconcentrated from aqueous samples followed by thermal desorption and GC analysis. The newly developed sol–gel hybrid titania coating demonstrated excellent pH stability, and retained its extraction characteristics intact even after continuous rinsing with a 3 M HCl or NaOH solution for 12 h. Furthermore, it could withstand temperatures as high as 320 °C. Practical application was demonstrated through the analysis of six aromatic amines in dye process wastewater. A linearity of four orders of magnitude was obtained with correlation coefficient better than 0.9982. The detection limits ranged from 0.22 to 0.84 μg L−1 and the repeatability of the measurements was <7.0%. The recoveries of these compounds studied in the wastewater were in the ranges 83.6–101.4%, indicating the method accuracy.