Could you be more precise? what do you want to extract? Which extraction phase do you consider? organic or aqueous one?
Actually, the protocol will depend on which type of molecule you want to extract from your plant…
I'll extract my plants with ethanol, acetyl acetate and chloroform. after drying, I want to sub-fraction each extract.
hope it is clear enough
The best way to do so is column chromatography, but both mobile and stationary phase will depend on what you want to extract.
Maybe this clue could be usefull: changing the pH could change solubility of some of your products into water by protonation or deprotonation. e.g. if there are some amine functions, protonating them with an acid will increase their solubility in water. Then a liquid/liquid extraction is possible. Nevertheless, this will not give you pure products, unless you are very lucky. It can helps to isolate a family of compounds contained in your fractions, like alkaloids, but a chromatography will be compulsory to purify them properly.
I hope my answer helped you, do not hesitate if you want more informations.
Sincerly
Dear Nour
In general there are three important steps to isolate chemical compounds from a plant : extraction, separation and isolation / purification.
As you said, you did extractions using three solventes, and each one can be submitted a separation by chromatographic techniques or liquid /liquid partition. You can repeat the separation many times, I.e., through many chromatographs . Inclusive the final purification.
Robin told you the Mobil and stationary phase depend of your extracts and of course the chemical compounds it's suppose you are working. I suggest you a bibliographic research about your plant in order to have some idea about them, if there is any.
Dear Robin, Punit and Olga
actually, i want to extract the volatile oil first by water distillation. then, i 'll extract using the 3 solvent. after that i'll test the extracts on a specific enzyme. the extract which has the best result i want to sub-fraction it to isolate a family of compounds or product if I am lucky -as Robin said- to test it on the same enzyme and repeat the separation many times. after that, i'll use GC-MS (for oil ), LC-MS, NMR, IR to identify the compounds. the isolation will be done by TLC preparative and HPLC preparative.
I'll be glad to lisiten to your ideas.
thank you all
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