Wet-pack method

Note 7. A well-packed column is essential to achieve high-efficiency elutions. There are two different methods to pack a column the dry and the wet method. In the first case the column is filled with the dry stationary phase, closed and the mobile phase is then pumped in. This method is suitable for silica-based beads, but not for polymeric beads, because this kind of material is prone to swelling when wet. Thus, high column back pressures, preferential channels and flow limitations due to a nonhomogeneous wetting of the stationary mobile phase could deteriorate the chromatographic performances of the column. When the wet packing method is used, the stationary phase is swollen and suspended in a solvent of similar density, and introduced into the column as a slurry. In this case the main drawback is the necessity to provide a reservoir for the column to keep the beads in suspension. 

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