Ultrathin phenyl-functionalized solid phase microextraction fiber coating developed by sol-gel deposition

A new sol-gel application for the development of SPME fibers is described. Phenyltrimethoxysilane (PTMOS) and methyltrimethoxysilane (MTMOS) were the sol-gel precursors used at different proportions, together with different water contents, catalyst and reaction time. It was observed that obtaining a good film quality was determinant for a good extracting fiber performance. The film thickness ranged 0.2-1 mu m and could not be increased by multi-coating processes. Apparently, a dense, non-porous microstructure was obtained. These coatings exhibited a strong hydrophobic character, as shown by the capability of extraction of long chain and apolar aromatic compounds, which, was comparable to that of the 100 mu m polydimethylsiloxane (PDMS) and 65 mu m carbowax-divinylbenzene (CW-DVB). The developed fiber has shown high thermal (350 degrees C) and organic solvent stability (ethanol, toluene and dichloromethane), thus bearing adequate characteristics to be associated to GC and potentialities that nay also envisage suitability for HPLC. The new fibers may be useful for the microextraction of non-polar compounds. although at trace levels and in simple matrixes only, due to the susceptibility to competition. (c) 2005 Elsevier B.V. All rights reserved.