Performance of octadecylsilylated monolithic silica capillary columns of 530 μm inner diameter in HPLC

Monolithic silica capillary columns were successfully prepared in a fused silica capillary of 530 mu m inner diameter and evaluated in HPLC after octadecylsilylation (ODS). Their efficiency and permeability were compared with those of columns pakked with 5-mu m and 3-mu m ODS-silica particles. The monolithic silica columns having different domain sizes (combined size of through-pore and skeleton) showed 2.5-4.0-times higher permeability (K = 5.2-8.4 x 10(-14) m(2)) than capillary columns packed with 3-mm particles, while giving similar column efficiency. The monolithic silica capillary columns gave a plate height of about 11-13 mu m, or 11200-13400 theoretical plates/150 mm column length, in 80% methanol at a linear mobile phase velocity of 1.0 mm/s. The monolithic column having a smaller domain size showed higher column efficiency and higher pressure drop, although the monolithic column with a larger domain size showed better overall column performance, or smaller separation impedance (E value). The larger-diameter (530 gm id) monolithic silica capillary column afforded a good peak shape in gradient elution of proteins at a flow rate of up to 100 mu L/min and an injection volume of up to 10 mu L.