Viscosity slurry packing technique for high-performance liquid chromatographic columns

The viscosity slurry packing technique for high-performance liquid chromatographic columns, both adsorption chromatography using spherical silica gel and reversed-phase chromatography using spherical ODS-silica, was investigated in detail to obtain high column efficiencies. Non-polar viscous solvent, a mixture of liquid paraffin and n-hexane as a dispersing agent for silica gel supports, and polar viscous solvent, a combination of glycerol and ethanol for ODS-silica supports, were applied to the slurry packing technique. Column dimensions were 4 mm in I.D. and 250 mm in length. Eluents were 1% ethanol in n-hexane for adsorption chromatography and 70% methanol in water for reversed-phase chromatography. High pressure during the packing procedure was necessary to obtain high column efficiencies. Use of viscous slurry solvents has an advantage of eliminating the problem of different sedimentation speed of the supports causing the longitudinal irregularity of particle size distribution, and also the requirement of a high pressure pump with large capacity. Three different sieve fractions of spherical silica gel (17, 23, 29μm) separated from the same silica gel prepared in our laboratory were packed with the same viscous slurry medium (22 cp) at the same pressure (200 kg/cm2), and the influence of the particle size on column efficiencies (HETP) was determined and compared with that of the balanced-density slurry packing technique investigated by R. Endele et al.