chromatography and adsorbent properties
So as far as I know silica is acidic, and alumina can be obtained in three different grades - basic, neutral and acidic.
1.) I am a little bit confused when it comes to the different pH grades of alumina as it relates to the efficacy of separation. It is my assumption
that either neutral alumina and silica can be used in most situations, but when dealing with certain molecules (like alkaloids for instance,
containing a basic nitrogen) a basic grade of alumina would produce better resolution.
2.) Now at first I figured that the "acidic" or "basic" property of the alumina was some sort of coating on the TLC plate, but it seems as though
activated alumina can be purchased for column chromatography as well, at different pH grades. I guess I am just a bit confused as to how this "pH
grade" for alumina is obtained in the industry. Would simply basifying a slurry of neutral alumina produce the same result?
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