[AoisPokemaster]

Hey guys, I am the person who was researching on curcumin a few days ago. Thank you for all the wonderful replies and my research had made substantial progress thanks to all of your contribution. I have another question here. When using column chromatography to separate the different curcuminoids in turmeric powder, many research papers suggests the use of a mixture of hexane and ethyl acetate in the ratio of 7:3, and upon performing TLC with the solvent, there was wonderful separation of the different curcuminoids. I have already attempted a large scale column chromatography with the solvent mixture, but I wish to understand why is it that we need to use the mixture of solvents? Is the use of different solvent systems like case specific? please explain in a manner as simple as possible. I am only educated slightly beyond a high school level.

[rolnor]

Nice that we can help you!
You need to mix the polar component in the mobile-phase with a non-polar component, otherwise the material you want to separate moves to quickely through the column and you dont get any separation.
https://en.wikipedia.org/wiki/Chromatography

[kriggy]

You can run columns with single solvents as well. Ive run pure hexane and pure EtOAc or DCM columns with not problems. It all depends on the specifics of each separation. You need to mix the polarity just right to get good separation. Often changing one solvent for another even with similar polarity can give you very different separation

[Babcock_Hall]

I second what Kriggy said about the utility of changing to a different solvent system of similar polarity for better separation.  Besides separation, there is sometimes the solubility of the analyte in a solvent that affects one choice, although there are some other ways around solubility issues.

[rolnor]

Yes, I did not give a complete picture, true, its a more complex matter. But often people use different mixtures. The fact that different solvents can donate and/or accept hydrogen bonds is important.

[wildfyr]

I'll never forget this column assay method for checking fractions for the active material.

https://blogs.sciencemag.org/pipeline/archives/2006/05/02/things_im_glad_i_dont_do_isolating_ciguatoxin

In the final column or two, the paper outlines a brutal but effective method for cutting fractions to get the ciguatoxin: take a sample from each cut of the column and inject it into a mouse. If it doesn’t die immediately, that fraction doesn’t have any ciguatoxin in it. Gloves recommended.

[rolnor]

That is truly non-ethical I would say.

[Babcock_Hall]

rolnor,

I agree.

[wildfyr]

Japanese paper from 1990

https://pubs.acs.org/doi/abs/10.1021/ja00167a040

I didn't even mention the part where they puree 4000 kg of eels as a starting material.