I'm attempting to extract withaferin-a from ashwagandha through a methanolic extract method. I extracted withanolides by adding ashwagandha root powder to methanol and agitating on a rocker for 8+ hours. I then separated the withanolides with a liquid-liquid partitioning method by filtering out the root powder and adding the methanol solution to a separation funnel. I added deionized water and dichloromethane, gently rocked the separation funnel for about a minute, and allowed the dichloromethane layer to settle to the bottom. I drained the dichloromethane layer, and then repeated this process two additional times. I then drained the methanol layer, added activated carbon to it, and allowed this to sit over gentle heat for about 10 minutes. I then filtered out the activated carbon (I triple filtered it, just to be careful) and allowed the methanol solution to evaporate in an evaporation dish set over heat. After it cooled, I then rinsed the dish out twice with n-hexane. The result is a syrupy, blackish-red layer in the bottom of the evaporation dish. According to the paper I am following by Keesara et. al. this can then be turned into a powder, but no method is given on how to do this. How can I turn the syrupy layer into a powder, which can then be tested to determine if I have been successful in extracting withaferin-a?
An obvious methodology might be to lyophylize (freeze-dry) your residue by any means available. A lyophylizer may even be improvised using a vacuum dessicator partitioned with the porous ceramic plate and dry-ice supplanted for dessicant, cooled to -78C (use an outer insulator) and high-vacuum applied (at least 70 torr).
Also, perhaps instead of Ch2Cl2, try 2-Methyl THF which is immicible in H2O and has far less environmental blowback. Recycle if possible. If you have lotsa $'s the skys the limit on lyophylizers.
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