I extracted a plant sample by soxhlet with chloroform for 8 h then methanol for another 8h. which way is better to fractionate the methanol extract, using sephadex or silica gel column? and what do you suggest as a mobile phase?
The plant sample extracted by soxhlet should be concentrated first. Then take TLC using different solvent systems of varying polarity. The solvent system which shows the maximum separation be used for column chromatograpgy. e.g. Petether, Ethyl acetate,Chloroform, Chloroform methanol mixture depending upon polariry for fractionation.
Hi Noura,
I agree with Madhukar, take silica gel using hexane, ethyl acetate and methanol in different concentrations.
Silica gel is suitable for fractionation and I also suggest the use of methanol gradient (100% - 5% v/v) until you have fractions separated by water.
Regards
Check these publications and link:
http://www.slideshare.net/rahulbs89/extraction-of-plant-contituents
Check this thread:
https://www.researchgate.net/post/How_do_you_fractionate_methanol_extract_for_flavonoids?_tpcectx=topic_detail&_trid=55409c2af15bc7a3178b45d3_16
You will get better results if you use Silica gel first and then (Gel filtration) Sephadex LH 20 on fractions therefrom. You should start the silica column with hexane or pet-ether or better yet hexane-ethyl acetate 9:1 to prevent "dewetting" and gradually ramp up the gradient to 100% ethyl acetate before starting with Chloroform-Methanol (i.e. Chloroform 100% with increasing amounts of Methanol till you reach 100% Methanol). Also you could look up Jack Silver on researchgate; he is a guru in all things column. Cheers!
FRACTION ATE METHANOL EXTRACT USING SILCA GEL AND ITS FRACTIONS WAS IDENTIFIED ON TLC PLATE
Fractionation of methanolic extract of leaves on can use column chromatography techniques .
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