Hydrodynamic Chromatography (HDC) was used as a purification method for packing materials (particles) in the micron to sub-micron range. Using HDC, the relative standard deviation for the size distribution of a batch of packing material was successfully narrowed from 33% to 16%. Subsequent chromatographic evaluation of this material, using capillary ultrahigh pressure liquid chromatography (UHPLC) showed significant improvement in performance and decrease in flow resistance over the unpurified material. The capillary time-of-flight (CTOF) instrument was envisioned and constructed. This instrument uses the poiseuille flow principle to measure solution viscosity at pressures up to 4000 bar. Another embodiment of this instrument enabled the simultaneous measurement of diffusion coefficient and the solution viscosity up to pressures of 2000 bar. Diffusion coefficient and viscosity data obtained from this instrument allowed for reevaluation of previously collected UHPLC data and provided significant new insight into column performance.