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Phosphoric acid evaps at about 200c so no.

Yes, that will work wonderfully. I recommend that you also combine your harmalas into the liquid before evaporating. IME, the comeup happens almost just as quickly whether drinking liquid or swallowing caps.

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An alternate to the humming bird cold water extraction, would be to simmer the MHRB for a bit -- that way, you can recover all the alkaloids rather quickly.
After that, there are various fining techniques you can use to reduce the amount of tannins, if nausea is too problematic.
The most effective fining method that I've tried is to reduce the liquid to a low volume and freeze it, then let it thaw in the refrigerator overnight. You'll see a lot of goo has formed on the bottom of the container and the liquid will be much clearer. Save the liquid, discard the goo. Do this BEFORE mixing in your (cat's) harmalas.

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Phosphoric acid is ok to eat, so no worries if it's left in the final product. Cold or hot extraction in an acidic solution(using phosphoric acid/vinegar/lemon juice/etc) will provide you with the salt, yes. The salt is water soluble and therefore what you want when using DMT orally.

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You may also like spiceman's oil baste tek, where cooking oil is used in the place of an industrial solvent.
The Poor Mans Tek - A 100% Fat Free, Food Safe, Grocery Store Solution to DMT Extraction

Next week, I plan to experiment with coconut oil using that tek. In the past, I've had good success using soybean oil and grape seed oil.
The cool thing about coconut oil is that is freezes easily. I will try to seperate the oil and water layers by making the oil layer into a popsicle and lifting it off the water.

No, just a little concerned that on evap there will be acidic residue that can't be driven off. Certainly the ph will go right down as solution approaches dryness. May or may not be a problem. I have noticed with evapping hcl spice solutions the final residue will often appear to 'char'. Unless someone here has first hand experience with the procedure you suggest, perhaps you might try evapping a plain phos acid solution at the strenth you intend to use and see what remains?

This is very similar to how I used to make mimosaroo.
Here is a thread with the exact recipe I used, with the exception that I added 300mg of 10x syrian rue instead of 30mg.
Questions on cold water technique

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