Preparation of mixed-mode stationary phase for high performance liquid chromatography with ground hybrid silica monolithic material

With polyethylene glycol as a porogen, vinyltrimethoxysilane (VTMS) and tetrame-thoxysilane (TMOS) as silica precursors, a hybrid silica monolithic material was obtained under the catalysis of acetic acid and thermally decomposed urea. The silica monolithic material was ground by a ballmill, treated with tris(hydroxymethyl) aminomethane (Tris), then washed and dried to obtain silica particles with particle size similar to 3 mu m. The effects of different reaction conditions on the particle size, surface morphology and dispersibility of silica particles were investigated. When the volume ratio of TMOS to VTMS was 3:1, it was observed that silica particles with a pore diameter of 7.5 nm and a specific surface area of 245 m(2)/g were obtained. The resultant silica particles were modified by binding with chlorodimethyloctadecylsilane (C18) and by the thiol-ene click reaction to obtain a mixed. mode type stationary phase. The test results showed that the silica packing materials prepared in this work has certain applicability.