[peptideismylife]

Hey people!

I am going to run a column chromatography..and as far as I know u have to put a cotton at the bottom of the column...but always? because I think that there are special column with something at the bottom that plays like the cotton? could be?

[rucik5]

Well, you need something on the bottom to stop the silica from running out with your solvent. I usually use columns with sintered glass (see picture) at the base. A plug of glass wool does the trick as well [I would put a thin layer of sand on the cotton as well - to prevent clogging/blocking]. I don't know about cotton wool.

I think it's a good idea to get someone to show you how to do it for the first time. After several columns you will develop your own technique. It is quite a popular technique, there is a lot of info on the web.

[Honclbrif]

As long as there's a sintered glass intrinsic to the column you're cool. Otherwise, you've got to come up with some way to keep all the chromatographic media from falling out.

[voidSetup]

I usually stuff a small piece of cotton in just above the valve and then a thin layer of sand before adding the silica.

[enahs]

If I know it is going to make my sintered glass hard to clean, I go with cotton wool my self. Sometimes I even just wad a KimWipe in there...Works great!