|
Trichocereus alkaloid extraction |
|
|
Written by (unknown)
|
|
Monday, 12 August 2002 |
|
Page 2 of 3
(optional) The stuff at this point will be a bit of a mess. Adding activated charcoal and boiling gently for 10 minutes will help to congeal the chlorophyll etc. which is gumming up the stuff. Do not add too much charcoal - less than a gram should be plenty. Too much will absorb alkaloids. Don't use burnt wood, burnt toast, etc - get the proper stuff from the local pharmacist. Performing this step will make the next stages considerably easier.
Filter the HCl extract. This will remove a proportion of the gunge. This will be easier if charcoal was used. The more gunge that can be removed at this stage, the better. Washing the residue with fresh HCl before discarding, and adding this to the rest will ensure no loss of yield.
Carefully basify the HCl solution with NaOH. I tend to use around a 5M solution for this, which is OK as long as you stir as it reacts. Take it well above pH 7. You should get white clouds of alkaloids forming in the solution, and the whole will become turbid as some of the acid soluble components precipitate. Ammonia or KOH should work for this purpose as well. I have had some difficulty with ammonia not being quite basic enough in other systems.
Add dichloromethane (or chloroform); be generous with the quantities if possible. Ideally, one would like to extract into CH2Cl2 3 times with equal volumes, but the amount of solvents gets huge. Ether is not all that good with mescaline extraction, I believe, even though it is easier to separate from water. CH2Cl2 is handy because it has a very low boiling point. It is at this point in the whole operation that the most care and patience is necessary. A separating funnel is really a must - one could plausibly separate the layers with a very tall thin jar and a syringe, but this would be difficult. Ideally, the basic solution and the CH2Cl2 will separate into 2 nice layers, the lower one (organic) containing the alkaloids. Unfortunately, while this is not difficult with most plants, it is very difficult with cactus extracts because the cacti contain so much resinous junk and natural surfactants (to retain water). The best way I have found to separate the layers once you have shaken them together is to add plenty of salt (NaCl) to the water/base layer. This is excellent for breaking the emulsions which form. Be prepared to use large quantities of salt.
Separate dichloromethane layer from mixture and put aside. Repeat steps 9-10 a few times: once is insufficient, three is good, four is excessive. Combine all the dichloromethane extracts together. This should be a slightly green solution. It will contain a bit of water, most likely.
Backwash the dichloromethane once with a solution of salt and NaOH (dilute). This will clean up the last of the junk from the organic solution. Separate the layers as before and discard all aqueous material.
Distill off the dichloromethane (or allow to escape to the atmosphere if you are rich and don't like the ozone layer). I have found that once you are down to maybe 20 ml of residue, the best option is to place the remainder in a petri dish (or some flat dish you are going to store it on) and hitting it with a hairdryer to remove any last CH2Cl2 and water. You should be left with a small quantity of moderately pure alkaloids. This can be easily consumed by dissolving in vodka, e.g., or should be stable for extended periods if refrigerated, frozen, kept airtight and away from moisture. Do not expect more than a 50% yield the first time you try this: theoretically if everything is done properly, the yield should approach 100%, but this is rarely the case.
|
