Step 5: Salt Formation and Extraction =====================================

The next step is to add acidic water to the xylene. This will cause the alkaloids to convert to their salt forms, which are soluble in water but not xylene. If using hydrochloric acid from the hardware store, it will already be diluted and may be usable as is. Read the label to find the concentration. One source says, "HCl from the hardware store is generally between 24%-36% HCl. This is far from dilute. Indeed, upon opening the container, a visible plume of white vapor can be seen creeping out of the bottle. First the lungs start to burn, then any skin which is exposed to the air starts to sting... This should be diluted, especially if it is going to be worked with without a fume hood. 20 drops acid per 500ml of water may even be sufficient."

If using vinegar (acetic acid), it comes quite diluted (around 5%) and should be used as is. It would probably be best to use plain white vinegar. I do not know what else is in vinegar other than water and acetic acid, but it is likely other chemicals remain from the original wine, and this may affect your final product. There should not be any harmful products from using vinegar, since it is a food-safe product, but you may not get nice crystals after evaporation.

If using citric acid (which is the recommended choice), prepare a solution of citric acid powder with a small amount of water. I recommend using citric acid because unlike hydrochloric acid, it is food-safe and safe to handle, and unlike either hydrochloric acid or vinegar, it is available in pure form. I have been told that using hydrochloric or acetic acid has the advantage that both are volatile and that excess will evaporate off, unlike citric acid. However, since neither are easily available in pure form, it is still probably better to use citric acid. Beware that if you do use hydrochloric acid and let it evaporate, the fumes can be hazardous and the evaporation should not be done where you might breathe in the vapors.

For this step, it is useful to have some idea how much alkaloid should be in your cactus extract. If you weighed your cactus before extraction. Trichocereus pachanoi has been analyzed with mescaline contents of 0.025-0.12% fresh weight (0.331-2.0% dry weight). Mescaline is usually around 50% or more of total alkaloid content. You will want to add an equimolar quantity of acid to the solution.

If you can't or don't want to estimate the alkaloid content, Trout gives the following work-around: add very small quantities of acidic water to the xylene, let separate, and then collect the water layer. Check the pH of the water, and it should be neutral. Repeat this with small batches of acidic solution until the water layers come out acidic. Trout points out that "Something to keep in mind is that neutralization won't always be immediate. pH should be checked after a few minutes to see how it is, adjusted if needed and rechecked a few minutes later."

If you are using citric acid and you are not worried about having citric acid powder in the final product, you can just add enough acidic water to make the solution slightly acidic, and repeat this once or twice, then combine the extracted water layers. As citric acid is both food-safe and a solid powder, this is a sloppy but safe approach. Shulgin suggests that this may be a better approach than stopping when the water layers stop coming out neutral: "My gut feeling is that there may be quite a bit of alkaloid still in the xylene, and maybe a couple of extracts with more aqueous acid would be useful. True, it may load the product down with excess citric acid, but the increased yield might be worth it."