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|Type:||Artigo de evento|
|Title:||Development Of New Urea-functionalized Silica Stationary Phases: Characterization And Chromatographic Performance|
|Abstract:||New urea-functionalized silica stationary phases were prepared by a single-step surface modification through reaction of LiChrosorb Si100 (5 μm particle size) with a homologous series of alkoxysilanes, synthesized in our laboratory, with the general formula (CH3CH2O)3Si(CH2)3 NHC(O)NH(CH2)nCH3, where n=4, 6 and 11. The modified silicas were characterized by elemental analysis of carbon and nitrogen, solid-state 29Si- and 13C-cross polarization magic angle spinning nuclear magnetic resonance and nitrogen adsorption isotherms at 77 K. Chromatographic evaluation of the three urea-functionalized silicas in 150×3.9 mm I.D. HPLC columns was carried out by the separation of a test mixture composed of uracil, acetophenone, benzene, toluene and naphthalene, using acetonitrile-water as mobile phase. These new stationary phases, with embedded polar urea groups, are very promising when compared with amide phases prepared by the conventional two-step modification process. A single-step reaction process silica modification is better for obtaining a well-characterized and homogeneous modified surface. © 2001 Elsevier Science B.V.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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