STUDY OF THE PACKING BEHAVIOR OF AXIAL-COMPRESSION COLUMNS FOR PREPARATIVE CHROMATOGRAPHY

The behavior of the packing of axial compression columns (5 cm I.D.) has been studied using IMPAQ C-18 silica (average particle size 17 mu m) as the stationary phase and water-methanol solutions as the eluent. Provided the frits used at both column ends are properly cleaned, columns of the same efficiency as analytical columns are easily and reproducibly obtained. The efficiencies of several columns for acetone (poorly retained), phenol (moderately retained) and cresol (strongly retained) were found to remain unchanged over periods' of 100 to 200 h. The column length was monitored during operations. It was found to decrease slowly over time, and to change when the packing solvent is replaced by the experimental eluent, and during gradient elution. It is smaller when the eluent contains more water. The total porosity and-the permeability of the axial compression columns were lower than those of analytical columns.