I've followed this tek through to the end and have had a fairly disappointing result. From using 80 g of white caapi I was expecting ~1.6g, so at least a gram for changa, plus a bit extra to experiment with sublingually. However I have ended up with a small, maybe 0.1-0.2 g by eye (don't have my scales right at this moment) of a brown powder, and a similar amount of a lighter brown/more tan coloured powder that was obtained after allowing some of the final rinse solutions (after the final addition of NaOH) to settle.
The brown powder must have a lot of plant material in it still I assume, though I thought that would've been removed earlier on after the addition of vinegar, then NaOH. In fact this was one of the only steps where I didn't quite follow the tek, as I added a lot of vinegar to try and dissolve more of the precipitate that seemed to remain. I must've added close to 200-250 ml of vinegar rather than the 50 ml the tek stated. Since a lot of the precipitate remained after this amount I assumed that it must indeed be plant material and figured that excess vinegar wouldn't matter, as long as I added sufficient base in the next step.
Looking back I feel there could be 2 things that could've affected my yield and I was wondering if anyone could shed some light on it for me. First, the white caapi I have was actually purchased ~2 years ago, though life being what it is I've been unable to experiment with changa and so it's remained in a box until now. However, I can't imagine there would be such a significant loss of harmalas from this.
Second, in the first step with the 4x boils, I added about 30-40 ml of 5% acetic acid vinegar for each boil. I wanted a bit more than 25 ml as I was using 16 g more caapi than the tek did, however my measuring jug only begins at 50 ml so trying to measure about 30 ml would've been quite inaccurate. I realise that as I was boiling, some of the acetic acid would've been boiled off as well but if I imagine that after reducing to ~400 ml I have about 4x30 ml of 5% acetic acid. I calculate there should be about 0.105 mol of acetic acid in solution and in the next step about 0.125 mol of NaOH is added (from the 5 g of NaOH). The base is still in excess, but not by much. Maybe I used too much acid/not enough base? I'm going to try this tek again with 70 g and perhaps use just 25-30 ml of vinegar for the first boil and a splash (maybe 5-10 ml) for the subsequent boils. Would this be enough? I see the tek says that some brews are done without acid, so I'm hoping so.
EDIT: wow sorry for the essay.