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Topic: Column chromatography problem  (Read 577 times)

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Offline Hachiko

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Column chromatography problem
« on: March 18, 2020, 10:57:08 PM »
Dear all,
My compound is low soluble so I need much polar solvent to dissolve it, when I runned column, I got the mixing. I think the reason is that my solution had low concentration and polar solvent make my sample all run together. I can't use dry loading because my compound can be soluble in solvent system. I try recrystallization but it's not good.
Could you share your opinion and experience when you handle with low solubility compound in column chromatography?

Offline phth

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Re: Column chromatography problem
« Reply #1 on: March 19, 2020, 04:02:02 AM »
Change the stationary phase, i.e. maybe alumina will work over silica gel or C18 or ion-exchange. You could try more recrystallization solvents; get some small test tubes and a hot bath. Test more and TLC solvent systems. If your compounds are not crystallizing/forming a gel at room temperature then lower the temperature.

Offline Hachiko

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Re: Column chromatography problem
« Reply #2 on: March 19, 2020, 05:02:19 AM »
Change the stationary phase, i.e. maybe alumina will work over silica gel or C18 or ion-exchange. You could try more recrystallization solvents; get some small test tubes and a hot bath. Test more and TLC solvent systems. If your compounds are not crystallizing/forming a gel at room temperature then lower the temperature.
Thank you for your suggestion.I will try different solvents for recryatallization.

Offline Babcock_Hall

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Re: Column chromatography problem
« Reply #3 on: March 19, 2020, 10:03:45 AM »
We have also experienced similar problems.  Can you tell us what your solvent system is and what solvent you are using to dissolve the solute?

Offline kriggy

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Re: Column chromatography problem
« Reply #4 on: March 19, 2020, 03:39:56 PM »
I dont understand, why you cant use dry loading?

Offline Hachiko

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Re: Column chromatography problem
« Reply #5 on: March 19, 2020, 10:52:37 PM »
We have also experienced similar problems.  Can you tell us what your solvent system is and what solvent you are using to dissolve the solute?
I use DCM for dissolve and 4Hexane:1Ethyl acetate for mobile phase.

Offline Hachiko

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Re: Column chromatography problem
« Reply #6 on: March 19, 2020, 10:56:25 PM »
I dont understand, why you cant use dry loading?
Oh,I may see my mistake here. I check the solvent system that I will use for mobile phase to dissolve my sample. My sample can be dissolved in this solvent system so I think dry loading is not good. So if I use dry loading and firstly run with hexane and increase the polarity slowly, will it be ok?

Offline kriggy

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Re: Column chromatography problem
« Reply #7 on: March 20, 2020, 02:55:31 AM »
Yeah thats pretty much what I do all the time. I dissolve the sample in DCM, add silica, evaporate to dryness, add to collumn and use hexane:EtOAc as a mobile phase. TBH I dont even bother trying to dissolve my samples in mobile phases I use :D

Offline Hachiko

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Re: Column chromatography problem
« Reply #8 on: March 22, 2020, 01:26:17 AM »
Yeah thats pretty much what I do all the time. I dissolve the sample in DCM, add silica, evaporate to dryness, add to collumn and use hexane:EtOAc as a mobile phase. TBH I dont even bother trying to dissolve my samples in mobile phases I use :D
thank you for sharing.

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