Re: Purification

From: Dave (tranmaster_at_hotmail.com)
Date: 07/13/04 

Date: 13 Jul 2004 08:58:23 -0700

When you say 85:35:4 Do you mean 80 ml CHCl3, 35 ml MeOH and 4 ml NH3(sat.)?

muhammar@hotmail.com (Muhammar) wrote in message news:<a6cffac9.0407081745.48788c25@posting.google.com>...
> Tou need to be more specific about the structure of your compounds.
>
> Aminos are nicely purified in chloroform-methanol-ammonia mixtures on
> *straight* silica. Carboxylic acids are typicaly retarded in ammoni
> system, byt then form very sharp zones. Since you have free carboxyls,
> you need exceptionaly polar mix (with lotsa aqueous ammonia) so that
> you compound (its ammonium salt) moves up at all.
>
> I suggest normal TLC-silica plates, eluted with mix CHCl3-MeOH-NH3
> (conc. aqueous) 80:35:4 or - if the spots move too slowly - with
> 80:50:5.
>
> Use Merck TLC plates. If you are doing detection with ninhydrin, you
> need to re-heat the eluted plate (before detection) with a heat gun
> until the plate stops smelling like ammonia. (You need to remove
> absorbed NH3 which would upset the detection)
>
> tranmaster@hotmail.com (Dave) wrote in message news:<d902d1a4.0407080519.249ab9a9@posting.google.com>...
> > I'm trying to purify Some polyaminocarboxylates by chromatography on
> > C18 Reverse phase silica. I find I get lots of streaking on my TLC
> > samples even putting a little bit of acid in the eluent and also some
> > sample stuck on the baseline. Can anybody suggest a good solvent
> > system for me to use to both limit the streaking and remove the stuff
> > stuck on the baseline?

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