Consolidation and column performance of several packing materials for liquid chromatography in a dynamic axial compression column

The mechanical properties of four different packing materials for preparative liquid chromatography were investigated. Their compression kinetics and consolidation behavior were measured under dynamic compression stress in a 5-cm LD. axial compression column. The internal and external porosities, the packing density, the permeability, and the efficiency of these columns were also measured. The materials studied included two spherical silica-based materials for preparative chromatography, NovaPak C-81 (6 mu m) and Hyperprep HS BDS C-18 (12 mu m), another octadecyl bonded silica material made of irregular shaped particles, Baker 1-130 C-18 (130 mu m), and an unmodified alumina (50 mu m) The first two packing materials showed much higher mechanical stability than the third one which experienced extensive particle breakage under high compression stress. The material with the smallest spherical particles (average size, 6 mu m) gave a stable, rigid column, but, either because it contains fine particles or because of a small degree of particle breakage, it caused problems. Maintenance after unpacking a column and cleaning the piston frit was difficult. This could lead to a significant decrease of the productivity. The behavior of the fourth column material, unmodified alumina, is very different from the ones of all silica-based materials so far studied; it is not superior to that of the three silica-based materials presented here. (C) 1998 Elsevier Science B.V. All rights reserved.