Please read this if you might find yourself extracting iboga, or pass it on if you know such a person. On top of the instructions in my 2002 publication on this subject and the Iboga Extraction Manual, there are two other suggestions I would like to add which can improve yields.
The first and most important is to use a strong acid, like hydrochloric acid, instead of the relatively weak acetic acid I proposed previously. When I first began this extraction research, I started with materials which would be safe, familiar and available for most people - vinegar and ammonia. A test of vinegar extraction on a single bucket of root gave exponentially less alkaloid with each successive extraction, suggesting that all the alkaloid in the root pulp was being exhausted. However, two recent experiments have demonstrated that the yield of TA and PTA are significantly (20-25%) higher when dilute hydrochloric acid is used instead of dilute acetic acid. I can only reason that some sort of "digestion" is facilitated by the hydrochloric acid to expose alkaloid to solution which would otherwise not be. The change this calls for in the procedure is to dilute standard concentrated (~30%) hydrochloric acid sixty-fold to render it a 0.5% solution, the same by weight as the acetic acid used previously. Also, since this approximately doubles the molarity of the acid, twice as much ammonia should be used for precipitating the TA. The disadvantages, which I had hoped to avoid when I proposed vinegar, are that breathing the fumes of the concentrated hydrochloric acid has to be avoided, and exposure of skin to even the dilute hydrochloric acid for extended periods should be avoided. Hydrochloric acid will tend to make holes in blue jeans. The only other drawback I can think of is that the nutritious waste water is no longer suitable to be applied to the garden, as I would expect chloride to eventually "salt" the soil. The increase in the yield of TA (30-80%) is higher than the increase in the PTA yield (20-25%), which means that the TA obtained using hydrochloric acid will be weaker than TA obtained using acetic acid.
The other suggestion is that when performing sequential extractions in multiple buckets, to check the dry weight of the TA in what is planned to be the final extraction, to verify that it is insignificant. The number of extractions I recommended was based on the experiment with a single bucket, when it was observed that the amount of TA from an extraction was about half the amount from the previous extraction. When a series of batches of root bark are extracted sequentially, the yields of TA do not decrease as quickly, so there is the risk of discarding the root bark pulp along with more remaining alkaloid than intended.
If you have not yet harvested the iboga bark, please consider purchasing ibogaine derived from Voacanga bark instead, such as from Bob Sisko. The iboga shrub has a limited range and grows slowly, and overharvesting is threatening the species with extinction.