Activating alumina before column chromatography

Recently I synthesized some amine compounds, and because it showed better separation in the neutral alumina TLC plates than silica plates, I am planning to purify the reaction mixture using neutral alumina column. In some texts, people often activate, that is, remove the water from silica or alumina by heating it at around 130-160 ℃ for 30-60 minutes in the oven before the column chromatography. However, in the catalog of Sigma Aldrich, I found this sentence.



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> For chromatogrpahy, alumina is usually used with organic solvents, and is treated with water to achieve different affinities, or activites, for specific uses. Sigma products are all activity #1, and water can be added to convert alumina to a lower activity grade
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As far as I know, the Brockmann activity is determined by the water content. Then, if I remove water from it, is the Brockmann acitivity of the alumina changed? Or does it have nothing to do with column chromatography and I don't need to care about it? Is the removal of water of silica or alumina before column chromatography essential procedure?


