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Check the pH before or after heating?

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MachineElf88

MachineElf88

Rising Star
Hey guys, when doing the acid boils do you get the pH to 4 before or after you heat.

DMT Handbook says to get the water to pH 4 then boil. Vovin's tek says so heat first then add the acid.

Anyone know which is correct? The pH drops upon heating so I've always got it hot first and then added the acid.
 
What I'm going to say it's just a guess, I'm not a chemist.

Well, that pH is needed to express the alkaloids in the acetate form. I believe the point of heating up the solution is to add kinetic energy, thus breaking more easily the bondings with the plant material and making also the collision between H+ ions and alkaloids more likely to happen.

So the correct pH should be maintaned throughout the whole process 😁

Do you get huge variations in the pH before and after the acid boil?
Acetic acid BP is 18-19 degrees above water's one, so if you manage to keep water volume constant and temperature at 100 °C you should also be able to keep your pH constant.
 
I use phosphoric acid and I find that to get the pH to 4 before heating requires a lot more acid. Also it could be that my pH meter is less accurate at higher temperatures.

Interestingly a mate of mine finds the opposite, he gets the pH to 4 before heating and then finds that it raises during heating and he has to add more acid, which is very odd.

On my next one I shall get the pH to 4 before heating and then check the pH once it's hot and see what the change is and report back.
 
phosphoric acid is a triprotic acid, which has buffer properties in the 4-5 pH range.
because it is a polyprotic acid, I wouldn't suggest its use for alkaloidal extraction. it tends to complicate things, resulting in a loss of yields and/or a mess.

pH is usually measured at room temp, 25C. consider: a pH probe is a semi-permeable glass membrane, which registers voltages (potential). to get an accurate reading, the environment should be isothermal, i.e. the temp inside the probe should be the same as the temp of the solution it is set in.
 
benzyme why would phosphoric result in loss of yield?

Surely it would work the same as any other if one is just going to boil with it and then freebase rather than use it to make a dmt salt? It's mentioned in the FAQ as an acid to use.
 
weird...
chemicalize.org is now chemicalize.com, and asks for an account to be created...


anywho, chemaxon's site does calculation to show pKa charge states for every entry search. phosphoric acid has four charge states, dmt has two. between pH 3 - 6, [hosphoric acid acts as a buffer (between the first and second pKa's). potentially messy precipitate, mixture of unwanted salts. this is just an educated guess...not to mention, algae and aspergillis love phosphates.

acetic acid is a simple, ubiquitous acid that won't complicate an extraction.
 
Alright, I'm gonna get me some white vinegar and give it a go. I'll report back, would be very interesting if indeed I get better yields with it.

As for checking the pH before or after heating this is what I've found with phosphoric -

When checking the pH after heating I find that for the first boil I don't need any acid as the pH drops naturally to 4 just from having the bark thoroughly mixed with the water (I grind the bark in my blender with water to make a mimosa milkshake, no dust that way). Once the solution gets hot the pH is 4.

For subsequent boils I need 20-30 drops of phosphoric acid to get the pH down to 4 once it's hot.


If I get the pH to 4 before heating I need much, much more acid, maybe nearly twice as much and what I found is doing it that way totally kills my yield. Then I'm boiling at what appears to be pH1.

Interested to hear your thoughts.
 
Getting it to pH4 and then heating totally destroys my yield. I've tested this a few times now.

I guess I have answered my question now but I'd be interested if anyone else finds a different result.
 
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