Phenylene-bridged hybrid spheres for high performance liquid chromatography

Highly monodisperse 1,3-phenylene-bridged hybrid organosilica spheres (m-PHS) were synthesized by co-condensation of tetraethoxysilane (TEOS) and 1,3-bis(triethoxysilyl)benzene (1,3-BTEB) using dodecylamine (DDA) and cetyltrimethylammonium bromide (CTAB) as templates. In this method, three important factors are the surfactants, the ethanol-water volume ratio and the TEOS/1,3-BTEB molar ratio. Their effects on the spherical particle morphologies were investigated systematically to optimize the synthesis conditions. With the optimal method, m-PHS was prepared with uniform particles in a narrow range 1.8∼2.5 µm. Likewise, highly monodisperse 1,4-phenylene-bridged hybrid organosilica spheres (p-PHS) were synthesized from TEOS and 1,4-bis(triethoxysilyl)benzene (1,4-BTEB) to compare the chromatographic properties with m-PHS. Both two hybrid materials can be directly used for reversed-phase high-performance liquid chromatography (RP-HPLC), showing high column efficiency, and the m-PHS stationary phase exhibits a much longer retention time and better separation ability for some aromatic compounds.