Hydrodynamic chromatography for the size classification of micron and sub-micron sized packing materials

Hydrodynamic chromatography (HDC) was used as a size classification and purification method for porous bridged ethyl hybrid (BEH) packing materials (particles) in the micron to sub-micron range. Using packed column HDC, a batch of particles with size 0.76 ± 0.26 μm was fractionated to yield classified material of 1.05 ± 0.16 μm, reducing the relative standard deviation from 33% to 15%. Subsequent chromatographic evaluation of this packing material showed significant improvement in column performance and decrease in flow resistance over the unclassified material. Comparing a column packed with the classified versus non-classified material, the effective flow resistance of the two columns was decreased by 58% and the minimum HETP for the packing material was improved from 4 to 2.5 μm.