Springer Science and Business Media LLC

Porous silica microspheres with bonded hydrocarbon phases have been prepared for high-performance reverse-phase liquid chromatography. These bonded-phase particles exhibit high efficiency because of their small size (∼7 μm), narrow particle size distribution, and excellent solute mass transfer characteristics. Slurry-packed 25 cm×0.32 cm i. d. columns of 7 μm particles modified with octadecyl groups (18% C) exhibit plate height of <0.005 cm with water/methanol mobile phases at 50°C. The high concentration of octadecyl, dimethylbenzyl and trimethyl groups that are introduced by reaction with chlorosilanes minimizes band tailing due to solute adsorption by residual silanol groups on the support surface. These small particles are prepared with different size pores, which determine the level of organic stationary phase and resultant chromatographic retention. These particles with various pore sizes permit optimum reverse-phase interaction with solutes of different molecular weight.