I'll be extracting compounds from Asparagus racemosus powder to determine synergism with antibiotics on a MIC plate using acetone, chloroform, methanol, and DMSO.
I'm planning on putting 100 g of root in an Ehrlenmeyer flask closed to air in 0.5 L of solvent for each of the solvents, 4 flasks in total. I'll keep them at room temperature for seven days, periodically moving the material around. After, I'll strain the undissolved material, dry it, determine weight and thus concentration of the extract.
Do I have my facts straight? If anyone had any suggestions, I'd greatly appreciate it!
Your planning is good but extraction of parental material will remain uncertain, it will be partial extraction. If the solvent is volatile than you have to remain cautious about reduction of volume, volatility and component loss.
Protect the flask from light and stirr with a magnetic stirrer (this will increase mass transfer). Also, you can sonicate the flask (an ultrasonic bath is enough) for faster extraction (see ultrasonic assisted extraction). You can improve the extraction method if you add the total solvent volume in fractions. Add the solvent in portions, e.g. 100 mL, and let stand (or stirr) for a time, e.g. 24 h, remove the extract, and then add to the root another portion of the same solvent and repeat so many times you want.
Consider that it is very difficult to remove DMSO from the extract (due to it high boiling point). Acetone could react with some compounds, but is a good solvent an easy to remove in a rotavapor. Chloroform is a good solvent, but there are safer alternatives like dichloromethane. Try also with a less polar solvent as ethyl ether, t-butyl methyl ether (a safer alternative to diethyl ether), hexane, hexanes or light petroleum ether(40-60°C).
Best regards
You may wish to consider pulverizing your sample by grinding it under liquid nitrogen to make a fine powder, then extracting it with a Soxhlet extractor: This would probably be more thorough.
http://en.wikipedia.org/wiki/Soxhlet_extractor
DMSO can be evaporated with a lyophilizer, by the way, although it is slow.
Very good the answer of Sebastian. You should know what is the best solvent for your antimicrobial compounds. Do you try to use a Soxhlet?
Best regards
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