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Topic: Flash chromatography tips?  (Read 6131 times)

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Offline mir

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Flash chromatography tips?
« on: June 24, 2006, 08:36:29 AM »
I tried doing a flash chromatography yesterday. But I ran imidiatly into trouble.
I packed to column correctly. And the flow rate was correct.
But the solvent system I used was probably incorrect. Even it worked pretty well on TLC. The Rf was wrong (0.6). It should have been around 0.35 I have recently learned. But anyway, I didnt get the fraction of product I wanted, I checked with TLC, but the product wasnt around anywere in the fraction before I ran out of solvent (the volume is instructed in a standardized table). This doesnt make sense. Could my fractioon be to dilute, to see in TLC? I even tried UV and a chemical that react with a color (hydrizine?) with an amine (my product), but no sign of product.

Can I compare the solvent systems in TLC with the solvent systems in Flash chromatography to find the correct Rf value?
Any tips around choosing solvents?

And I also wished to have five arms and two heads while doing the separation, it went to quickly (the instructions tell 2.5 cm/30 seconds). My column was emptied in only ten minutes. I suppose when I am out of solvent the separation is finish?
No single thing abides, but all things flow.
Fragment to fragment clings, and thus they grow
Until we know and name them.
Then by degrees they change and are no more
The things we know.
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Offline chiralic

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Re: Flash chromatography tips?
« Reply #1 on: June 26, 2006, 11:11:51 AM »
Hi mir:

I recommend you visit this page...on this page you can find some tips on flash chromatography:

http://www.labhut.com/education/flash/index.php

Regards,

Chiralic

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