Best way to get acetic acid?

G

Geeky-Donut

Well-known member
I'm diving into the peptide threads and wondering where everyone sources their acetic acid, and what kind you're using. I'm tempted to just grab some distilled white vinegar and slowly add it to bacteriostatic water, checking the pH as I go. Does anyone have a preferred method or source for acetic acid? While I'm not overly worried, a low pH reconstitution solution seems like a good idea.
 
If you're aiming for an AA concentration around 0.6%, a mix of 75% AA and 25% BAC water should work. But remember, store bought vinegar lacks USP certification and may contain unfiltered sediments. If you're using a 5% AA vinegar, add a couple of drops to 1ml of BAC, measure the pH, and filter the solution. I found multiple vendors online that sell 0.6% AA solution. Check lab supply sites.
 
I got mine from an Australian site. I haven't used it yet, and I'm two weeks into my cagri journey.
 
A few months back, I tried the vinegar and bac water approach with a vial of cagrisema, and it immediately got cloudy. I think the vinegar denatured the peptide, kinda like when things get weird when adding acid in cooking. The peptide was ruined and couldn't be saved. I'm not sure why it happened, because vinegar *is* acetic acid, but it seems like it doesn't work the same way. Just a heads up so you don't ruin your peptide!
 
Thanks for the warning! That's really helpful.
Wes_80 said:
I tried the vinegar and bac water approach with a vial of cagrisema, and it immediately got cloudy...
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Did you mix the BAC and vinegar first, or add them separately to the vial? I went with plain BAC for now, and cagri seems to be working really well, just like when I started sema. Maybe I'll experiment with vinegar later, but I don't want to waste a vial I might need.
 
Just using vinegar or glacial acetic acid alone doesn't seem quite right to me. You might get to pH 4.0, but it won't necessarily stay there. Things like CO2 from the air or impurities from the needle could change it enough to be a problem. I'm thinking a biocompatible buffer would be smart. They use sodium acetate in pramlintide solutions. Is there a reason people aren't using sodium acetate or something similar to buffer the cagri?
 
Exactly! The whole point of using acetic acid instead of HCl/NaOH is to create an acetate buffer instead of a phosphate one. If you're using a cagri vial in less than a month with 4 injections, how much does the pH even fluctuate? And how much does it really matter in terms of degradation? I'm not sure we even know. Some people are adding lidocaine, which contains both hydrochloric acid and sodium hydroxide to maintain a pH of 6.5-7. Acetic acid + sodium hydroxide = sodium acetate + water.
 
It's not about the cagri itself degrading, though.
Ratched77 said:
If you're using a cagri vial in less than a month with 4 injections, how much does the pH even fluctuate?
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The problem is that it can clump into fibrils, which are known to be toxic. We don't have data on how sensitive that process is to pH, or how it changes with time and temperature. We just know it's less likely to happen at pH 4 than at a neutral pH. That's why I think it's best to do what the drug companies do and use a buffered pH 4 solution.
 
Yeah, I saw somebody mention this the other day. It's pretty handy if you're not sure how much bac water you need to add. Here's one I found: another forum
 
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