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Abstract
With optimised packing procedures, spherical shaped silica gel particles produce 1.5 to 2 times more plates in HPLC than irregular shaped silica gel particles. The lowest reduced plate height obtained by us so far is for 5 μm ROSiL-C18-HL-D and is h: 1.62 for k': 4.5. It is suggested to transform h into 100/h% and to name this the “Chromatographic efficiency”, or a % of the ideal 100% limit. This limit would be an h value equal to the mean particle diameter. Spherical and irregular silica gel particles of 5 and 10 μm particle diameter and with similar physical characteristics have the same permeability in HPLC columns.
Whether a correct column packing procedure is used can be shown by the constancy of plate number and column permeability in function of different packing pressures.