Highly porous solid-phase microextraction fiber coating based on poly(ethylene glycol)-modified ormosils synthesized by sol–gel technology

The preparation and characteristics of solid-phase microextraction (SPME) fibers coated with Carbowax 20M ormosil (organically modified silica) are described here. Raw fused silica fibers were coated with Carbowax 20M-modified silica using sol–gel process. Scanning electron micrographs of fibers revealed a highly porous, sponge-like coating with an average thickness of (8 ± 1) μm. The sol–gel Carbowax fibers were compared to commercial fibers coated with 100 μm polydimethylsiloxane (PDMS) and 65 μm Carbowax–divinylbenzene (DVB). Shorter equilibrium times were possible with the sol–gel Carbowax fiber: for headspace extraction of the test analytes, they ranged from less than 3 min for benzene to 15 min for o-xylene. Extraction efficiencies of the sol–gel Carbowax fiber were superior to those of conventional fibers: for o-xylene, the extracted masses were 230 and 540% of that obtained with 100 μm PDMS and 65 μm Carbowax–DVB fibers, respectively.