Synthesis And Characterization Of Silica And C18 Bonded Phase

Using commercialized silica sol as silica source, an improved process of PICA (Polymeric induced colloid aggregation) method was used to synthesize porous silica microspheres. The silica microspheres with a very narrow particle size distribution can be used for HPLC column packing. The effects of type and amount of silica-sol, temperature, solution pH, stirring speed, the concentrations of urea and formaldehyde, and the sintering conditions on aggregated microspheres were studied to find optimal conditions. The characteristics of the porous silica particles were characterized by SEM, FT-IR, BET method et al. The results showed that the silica particles synthesized by PICA have an average diameter of 3.5μm, a surface area of 114.1m2/g, an average pore volume of 0.65cm3/g, pore diameter of 17.8nm, the a-OH is 3.444μmol/m2 and the particle size distribution width is less than 2.0. The characteristics are all in line with the use of HPLC packings.C18 silica bonded phase was prepared through Silylation reaction from silica and Octadecyltrichlorosilane, and which was end-cappinged by Trimethylchlorosilane. Compared the bonded phase with the traditional ODS, the results show that the bonding capacity and stability of the existing method were excelent, and the result of FT-IR showed that the peaks at 2929.37 cm-1 and 2858.38 cm-1 were-CH2-stretching vibration. The organic content was measured by TG analysis, and Organic bond rate is 11.91%, it indicated that chlorosilane silica bonded phase is identical with some commercialized ODS. The result of chromatography showed that the standard substances were separated very well on C18 silica bonded phase, and the separation was comparable with commercialized ODS.The study gives a method to get the silica gel and C18 silica bonded-phase, which can be used for the high performance liquid chromatography, and it is very important to help optimize the preparation process of silica packing.