Synthesis and characterization of titania based stationary phases using the silanization/hydrosilation method

Abstract

SummaryThe silanization/hydrosilation bonding method is tested on both a laboratory synthesized and commercial titania. The laboratory titania made by the sol-gel process shows evidence of residual organic material that is removed by an initial acid hydolysis followed by bonding of the hydride (triethoxysilane) under acidic conditions. DRIFT and solid state CP-MAS NMR studies are used to confirm the formation of the hydride layer on the titania and the success of the hydrosilation process for attaching an organic moiety (1-octadecene) to the surface. Chromatographic testing, primarily on the commercial titania based C-18 phase, indicates good reverse phase properties and few residual OH groups, either Ti-OH or Si-OH, as determined by the symmetrical peak shapes obtained for anilines and alkylphenylamines using mobile phases with no buffers or masking agents in the aqueous component.

Comparison of octadecyl bonded titania phases

“…Then, these clusters of organosilanes react with the surface of the inorganic oxide, become immobilized on it, and continue to polymerize with each other. The second method is called the silanization/(surface) hydrosilation modification procedure [12,14,15]. First, a monolayer coverage of hydride material is produced (in the silanization step) due to the reaction of the inorganic oxide surface with the hydrolysis product of triethoxysilane (TES).…”

“…The different chemical Surface properties compared to silica gel indicate the usefulness of zirconia and titania, for the separation of basic analytes that are not easily separated on stationary phases based on silica due to the affinity of its surface hydroxy groups towards basic substances. In recent years octadecyl phases based on titania have emerged as a useful material for HPLC separations [8][9][10][11][12].…”

Suportes cromatográficos e fases estacionárias para cromatografia líquida: preparo, evolução e tendências

“…Entretanto, esse suporte cromatográ-fico apresenta eficiência cromatográfica inferior aos materiais baseados em sílica e, consequentemente, esse fator contribuiu para a utilização moderada desse suporte [38,39] . Suportes cromatográficos baseados em óxido de zircônio (zircônia, ZrO 2 ) [40] e óxido de titânio (titânia, TiO 2 ) [41,42] apresentam boa estabilidade em pH entre 1 e 14 e sob temperaturas de até 200 °C. A superfície desses materiais apresenta sítios ácidos de Lewis e, consequentemente, fases estacionárias baseadas nesses óxidos têm demonstrado modo misto de retenção (fase reversa e troca iônica, por exemplo).…”

Fases estacionárias para cromatografia líquida de alta eficiência em fase reversa (CLAE-FR) baseadas em superfícies de óxidos inorgânicos funcionalizados

“…Com a ligação ºSi-C embutida, este recobrimento também proporciona uma alta estabilidade hidrolítica destas fases 59 .…”