Novel benzo-15-crown-5 sol–gel coating for solid-phase microextraction

A novel dihydroxy-terminated benzo-15-crown-5 was synthesized and applied to prepare a solid-phase microextraction (SPME) fiber coating with sol–gel technology. The optimization of the sol–gel process was studied. The coating method with sol–gel was improved and completed in one run, which economized materials and allowed easier control of the fiber thickness. The repeatability of coating fiber to fiber was better than 4.94% (RSD). The surface of the fiber coating was well-distributed and an electron microscopy experiment suggested a porous structure for crown ether coating, providing high surface areas and allowing for high extraction efficiency. The coating has a high thermal stability (350 °C), long lifetime and can stand solvent (organic and inorganic) rinsing due to the chemical binding between the coating and the fiber surface. Non-polar benzene, toluene, ethylbenzene, xylenes, chlorobenzenes, polar phenolic compounds and arylamines were used to evaluate the character of the fiber coating by headspace SPME–gas chromatography technology. For phenols, the linear concentrations ranged from 5 to 1000 μg/l, the detection limits were between 0.05 and 1 μg/l, and the RSD was less than 5%. The addition of benzo-crown ether not only increases the thermal stability of the fiber coating, but also enhances the selectivity of the fiber coating. Compared with commercially available SPME fibers poly(dimethylsiloxane) and polyacrylate, the new phases showed better selectivity and sensitivity towards non-polar and polar aromatic compounds.