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Topic: **Tip for column chromatography  (Read 14342 times)

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Offline PhosMAN30

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**Tip for column chromatography
« on: April 24, 2008, 01:06:07 PM »
One of the best tips for loading columns w/ sample came from Dylan S. at Stanford.  Many compounds are soluble in toluene and it makes an awesome load solvent most of the time.  The only times when it does not work well is when the molecule is really non-polar and the conditions for elution are of low polarity ie. 95:5 Hex: EtOAc and/or the compound is simply not soluble in toluene.  What's great is when it works you can clearly see the band of toluene fly off the column in the initial flush and in case you're blind you can smell it.  **As with any load solvent you should use a minimal amt. when loading.

Offline Jd1828

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Re: **Tip for column chromatography
« Reply #1 on: April 27, 2008, 10:07:57 PM »
I've never heard of doing this.  What is the benefit to using a load solvent over just using solvent that you are running the column with?

Offline Mitch

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Re: **Tip for column chromatography
« Reply #2 on: April 27, 2008, 11:24:12 PM »
Minimizes diffusion into the eluent is the obvious one. The next one is a determination of a more meaningful relative retention time
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Offline Jd1828

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Re: **Tip for column chromatography
« Reply #3 on: April 28, 2008, 08:36:00 AM »
That makes sense.. Ill have to give this a try next time I run a column. 

Offline Capn Jack

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Re: **Tip for column chromatography
« Reply #4 on: March 29, 2009, 09:44:46 AM »
Just curious- why wouldn't the compound fly down the column with the toluene band?

Offline kiwi

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Re: **Tip for column chromatography
« Reply #5 on: April 02, 2009, 02:49:16 AM »
I've never heard of doing this.  What is the benefit to using a load solvent over just using solvent that you are running the column with?

Load solvents help get maximum solubility in minimal solvent (avoiding band broadening for starters). DCM (the minimum quantity to get a pipette-able solution) almost always works out here imho, except for very non-polar compounds. In that case I usually load the compound adsorbed onto a little silica. But I'll give toluene a go next time.

Offline macman104

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Re: **Tip for column chromatography
« Reply #6 on: April 02, 2009, 11:09:31 AM »
I usually use DCM as well.  However, I always get nervous using it that it'll wisk my compounds away with it, and I'll get no separation.  I'm a fan of adsorbing compounds onto silica and loading that way.  Pretty easy, and never seem to have any problems with it either.  But I may have to give the toluene a shot as well...

Offline StarvinMarvin

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Re: **Tip for column chromatography
« Reply #7 on: May 07, 2009, 06:05:56 PM »
I worked for some time with sugars and also became a big fan of silica adsorption. In my opinion, it's just one of the best methods of sample loading.

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