I use the tek posted by 69ron, only I substitute FASW(fumaric acid saturated water) for the vinegar.
Here's the version I have saved for myself (it's the original posts, copied & pasted; I changed some of the wording so that it flowed better for me, but it's still the same instructions.)
69ron's Food Grade DMT Tek
It's basically a double A/B.
Here are all the steps to end up with freebase DMT using just d-limonene:
1 - Powderize your mimosa bark. Mix 100 grams of bark with 25 grams of calcium hydroxide. Add enough water to make it feel wet but not watery. Mix thoroughly.
2 - Add 300 ml of d-limonene. Mix very thoroughly.. Let sit a few hours or overnight, mixing now and then (THOROUGHLY!!).
3 - Pour off the d-limonene through a filter.
4 - Add 25 ml of vinegar to the d-limonene. Mix thoroughly....i.e., the separatory funnel "cha cha".
4 option: instead of using vinegar, add 25 ml of FumaricAcidSaturatedWater (150mg fumaric acid per 25ml DH2O) for every 75 ml of d-limonene; mix gently, but thoroughly
5 - Separate the vinegar from the d-limonene (vinegar is bottom layer, d-limonene is top layer). This vinegar will contain DMT acetate. Evaporate your vinegar in a food dehydrator at 155 F to get sticky DMT acetate.
5 option: separate the FASW from the d-limonene (FASW is bottom layer, d-limonene is top layer); next, bring the DMT saturated FASW to near freezing and most of the excess fumaric acid will sink to the bottom of the water and can be filtered off; lastly, evaporate to reveal nearly pure DMT fumarate with traces of fumaric acid as the only contaminant.
6 - Repeat steps 4 & 5 at least 2-3 times,
7 - Repeat steps 2 - 6 at least 2 times.
Bufoman's Method of Removing Excess Fumaric Acid:
To separate the desirables from the fumaric acid one simply adds 12mL H2O per gram of material. (the DMT fumarate is soluble in the water while the fumaric acid is not).
The aqueous (now yellow) solution is carefully decanted into a clean beaker or drying surface.
The water is reduced by 1/2 with a hair drier and then allow to sit open to the air and slowly evaporate.
Within a day (at most) large transparent crystals will begin to precipitate out one can collect these. (If one does not care about ascetics the solution can just be rapidly evaporate with a hair drier or on the oven and the crystals utilized right away. However SWIM recommends the crystallization.)
The remaining solution is then reduced again with a hair drier and allowed to sit as before. Once it has fully evaporated the crystals can be collected.
One now has highly pure DMT fumarate. The crystals are very nice to look at. One can attempt to wash the fumaric acid crystals again with an additional 10mL of H2O to see if any crystals are obtained however due to its solubility most of the DMT fumarate will collect during the first attempt.
I've performed this tek twice, using FASW substitution, and the spice came out great. The yields were pretty good too. I'll find my notes. I also used it for chaliponga once, without any extra steps such as defatting...it came out nicely too. I have not done any bioassays with the mimosa or chaliponga fumarates, but I have tested a bit of changa saturated with freebase made from some of the mimosa fumarates...it's good!
....I have a nice neat little document containing the above tek along with freebasing methods and directions for changa preparation...if anyone wants to take a look at it...all food grade methods.
I'm getting too tired to type..... if I've forgotten to say something obvious or you want me to lend some more details, I look back later.
PEACE
Edit: oh yeah, in the step 5 option, I didn't bring the FASW to near freezing to remove the excess fumaric acid, I used the water recrystalization by Bufoman.