Effect of domain size on the performance of octadecylsilylated continuous porous silica columns in reversed-phase liquid chromatography

We prepared continuous porous silica columns having double pore structures with micrometer-size co-continuous through-pores and silica skeletons which have mesopores. The through-pore volumes and the ratio of through-pore diameters to silica skeleton diameters were kept constant, and the domain sizes were varied between 2.3 and 5.9 mu m. We examined the effect of the domain size on the performance of silica rod columns in reversed-phase liquid chromatography after octadecylsilylation. The rod column having a smaller domain size showed lower plate height, though not so low as expected based on their skeleton size, and a smaller effect of linear velocity of mobile phase on the plate height for alkylbenzenes. The tendency was more pronounced for a larger molecule such as insulin. It was found that flow resistance parameters and separation impedance of the rod columns were smaller than those of conventional packed columns by a factor of 5 or more and showed little dependence on the domain size. The silica monoliths with double pore structure can provide a higher efficiency at a lower back pressure than conventional particle-packed columns. (C) 1998 Elsevier Science B.V.