lok_madscience
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vacuum-assisted soxhlet extraction
I would like to run an EtOH soxhlet extraction of various herbs, but I don't want to run it at ~80C. So, I'm thinking about hooking up a
vacuum to the top of the condensor, to reduce the boiling point. However, I'm worried about imploding my precious 1000ml chinese bomex extractor.
Has anyone ever tried this?
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Sandmeyer
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| Quote: | Originally posted by lok_madscience
However, I'm worried about imploding my precious 1000ml chinese bomex extractor. |
Well, I'm not an expert in soxhlet extractions, I have never done it, but consider what will happen to the ethanol, don't you think it will
leave the soxhlet system via vacuum source at a vacuum capable of imploading glassware? Besides, what's the reason for such rigorous temperature
control in the first place? Are you maybe worried about the material decomposition at 80 C?
can't you use methanol or ether? i think you will loose solvent if you apply vacuum unless you connect some sort of specially cooled condenser.
It seems more simple to switch solvent, don't you think? Anyways, I should not talk about things I have never done, sorry...
[Edited on 29-9-2005 by Sandmeyer]
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lok_madscience
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I plan on running a weak enough vacuum so that the condensor can condense the ethanol before it leaves the system. I'll cool with ice water.
The problem is not the heat of EtOH dripping on the herbs, but the concentrated extracts left boiling in the round bottom flask. I recently tried
doing an EtOH extraction of Damiana and saw smoke rising up the condensor. Also, there was a tarry substance left in the round bottom that looked sort
of like polymerization from heat induced reactions. In any case, there are heat labile constituents in many herbs that I would like to keep intact.
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lok_madscience
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You make a good point. If this doesn't work I was going to try hexane or pet ether, evaporate the solvent and redissolve in EtOH. The point is
that I want a final EtOH tincture.
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unionised
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Use lots of ethanol so that, even when the soxhlet is full, there is still plenty of solvent in the flask to keep the extract cool.
Then you can distill off the ethanol (under vacuum if you need to)
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