Innovative Cavitand-Based Sol−Gel Coatings for the Environmental Monitoring of Benzene and Chlorobenzenes via Solid-Phase Microextraction

An innovative and very selective solid-phase microextraction coating synthesized by sol−gel technology was developed for the determination of environmental pollutants such as aromatic hydrocarbons at trace levels in air, water, and soil samples. The obtained fibers, composed of quinoxaline-bridged cavitand units, were characterized in terms of film thickness, morphology, thermal stability, and pH resistance. Fibers, characterized by an average thickness of 56 ± 6 μm, exhibited an excellent thermal stability until 400 °C and a very good fiber-to-fiber and batch-to-batch repeatability with RSD lower than 6%. Finally, the capabilities of the developed coating for the selective sampling of aromatic hydrocarbons were proved, obtaining LOD values in the subnanogram per liter range. Extraction efficiency at least 2-fold higher than that obtained using commercial devices was proved for chlorobenzenes sampling in river water, obtaining extraction recoveries ranging from 87.4 ± 2.6% to 94.7 ± 1.9%. The selective desorption of benzene in the presence of high amounts of other airborne pollutants was also demonstrated.