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General Alkaloid Extraction |
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Written by (anonymous)
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Tuesday, 12 August 1997 |
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Page 3 of 3
The white precipitate is the alkaloids. The more the better.
Next, add equal volume of non-polar solvent (dichloromethane) to the mix. Place in separating funnel, and shake. Separate. This may be very difficult or slow. Adding more solvent, more basic water, etc. may help. Adding lots of salt to the water layer will help break an emulsion. Ideally you want to do this step 3 times - to extract as much as possible from the water layer into the organic. I find this part very difficult, and you have to accept that you will lose quite a lot of material here. It is, however probably easier with some plants that others: cactus is very difficult, barks and seeds would be easier. Use plenty of salt, and agitate to separate.
When you have finished extraction, chuck the basic water layer. The solvent layer is kept, and can be backwashed with salty water for a cleaner mixture.
The solvent can now be dried, (using salt or some dry powder, the filtred) (I don't usually bother with this - the old hairdryer at the end can remove some last solvent and water) then strip the solvent in a vacuum to get your final product - some kind of syrup could be expected. This is super concentrated, but may only be half the strength of the original. e.g. put in enough for 10 doses of morning glory seeds, get back 5 doses or more of concentrated alkaloids.
If it is desired to take the process still further, you can do the obvious thing - mix your solvent layer with dilute acid again and extract back into water. Acid layer could be evaporated under vacuum to give salts of alkaloids. Alternatively, if the organic layer were scrupulously dry, bases could be salted out with some organic acid - a tartrate, oxalate could be formed. I have never bothered with such things - you would need a lot of pure extract to be bothered. The acid-base extraction process can be continued as many times as is desired.
If a truly pure product is desired, the only way to go from here is chromatography. I have never used this at home, and wouldn't think it was worth the trouble, but there will be papers available on what was used for a particular extraction case.
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