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Unpacking and care of used packings

Kromasil silica is superior when it comes to mechanical and chemical stability, and can therefore, under most circumstances, be reused over and over again.

Kromasil can be stored either as a dry powder, or in a solvent. For storing the silica in a solvent it is recommended that you unpack and store the used silica in the solvent that you later will use in the packing process as a slurry solvent. For recommended slurry solvents please see our packing instructions.

Kromasil bare silica, and packings used in normal phase mode:

If you intend to use toluene/2-propanol as a slurry solvent during your next packing, you should, before unpacking, switch to pure 2-propanol. You should allow at least 3 column volumes of solvent to flush through the silica. This will clean the silica, as well as being a good solvent for storing.

Kromasil reversed phase silica:

When unpacking a reversed phase silica, it is important to first rinse the column bed from any buffer. Recommended mobile phases for this are for instance 2-propanol/water, ethanol/water, or methanol/water. After that all water should be flushed out using 100 % of a water-soluble solvent. We recommend for instance 2-propanol, ethanol, or methanol. Before unpacking you should then switch to a packing solvent in the same way as for bare silica.

To store Kromasil dry, apply the methods above, and use either acetone* or THF as the last solvent. Unpack the column, and dry the packing in an oven at 90 °C for derivatized Kromasil, and 120 °C for bare silica.

* For Kromasil NH2, only THF is recommended, since acetone will react with the amino phase.