Synthesis of chemically bonded squalene(ane) phases for microcolumn gas chromatographic separation of low-molecular-weight hydrocarbons in extraterrestrial atmospheres

Chemically bonded squalane(ene) phases have been synthesized via a hydride modified silanization process using dimethylchlorosilane, triethoxysilane and trichlorosilane. The surface structure of the bonded phases were characterized with DRIFT and solid state NMR studies. The results of the latter indicate successful bonding of a non-terminal olefin to the silica surface and that bonding of individual squalene molecules appeared not to occur at the same site(s) presumably due to steric hindrance. Among the phases examined, the trichlorosilane-based material exhibits better chromatographic properties probably due to greater surface coverage and hence effective non-polar interaction between the solutes and the bonded ligands. Under isothermal conditions, the present packings produced fast and efficient separation of C-1-C-4 saturated hydrocarbons on shorter columns than similar columns containing alkyl- or bidentate alkyl-modified silica packings at low column head pressure and are thermally stable at temperatures up to 250 degrees C or higher.