EFFECTS OF KINEMATIC VISCOSITY OF THE SLURRY ON THE PACKING EFFICIENCY OF PEEK MICROBORE COLUMNS FOR LIQUID-CHROMATOGRAPHY

The kinematic viscosity of the slurry used for the packing of microbore columns for liquid chromatography has been correlated with the packing efficiency. The columns were packed into polyetheretherketone (PEEK) tubing with an internal diameter of 0.5 mm using unbonded and bonded spherical silica gels under constant pressure conditions. Higher efficiencies were obtained using slurries suspended in aqueous solutions of surfactants, such as polyoxyethylene sorbitane monolaurate (Tween-20) and sodium dodecyl sulphate, in comparison with organic solvents usually used for column packing. The concentration dependencies of the relative kinematic viscosities of six slurries were compared using capillary viscometry. The slurries with low relative viscosities possessed theological properties which enabled high packing densities, typical of a stable dense random packing arrangement, to be obtained at moderate packing pressures. The unusually low relative viscosities are discussed in terms of a ''porous hydrodynamic bearing'' model. The techniques used should also be generally applicable to the slurry packing of conventional columns.