Also, “Disodium EDTA” is for acidic pH (- 7.0) and “Tetrasodium EDTA” is for alkaline pH (+ 7.0).
@Rafacasti What would happen if you used tetrasodium EDTA in products with an acidic pH?
I’m asking because we ran out of disodium EDTA for a while and we ended up using tetrasodium for a good amount of batches until we got some more delivered. All the products we formulated at that time were acidic. I was told they were more or less interchangeable.
Hello, Adamn! I’m sorry for delay in replying!
Not too sure about the details, but as @PhilGeis said, it evolves solubility (and other little things)
- Disodium EDTA
Sodium cations: 2 (per molecule)
Atoms of hydrogen: 4 (two of them are binded with the sodium cations)
Molecular mass: 336.2 g/mol
pH: 4-6 (sometimes 7, but never higher)
Soluble in: water
- Tetrasodium EDTA
Sodium cations: 4 (per molecule)
Atoms of hydrogen: 4 (all of them are binded with the sodium cations)
Molecular mass: 380.1 g/mol
pH: 10-11 (sometimes higher or lower, but never lower than 7)
Soluble in: water, ethanol (slightly)
Also, presents a higher potential to “sequestrate” metal ions
Both of them are subproducts of EDTA synthesis, used as chelating agents (and sometimes as preservatives, if I’m not wrong)… I heard once that Tetrasodium EDTA is more irritating and presents ecotoxicity in some way, but I’m not sure about that.
Anyway, I have no examples of incompatibilities between ingredients and these two forms of EDTA, but I think it would make little to no difference in your formulations (as I supposed you’re using low concentrations)… At least in my country (Brazil) I saw Tetrasodium EDTA far fewer times when compared to Disodium EDTA (most of the cases with Tetrasodium had both)
Sorry if this wasn’t the answer you wanted, but it’s all I could find and remembered. Hope it helps in some way! (:
I admit that I’m particularly skeptical about patents because I don’t really understand if there’s really a backing for all of them (even though this one in particular is from The Procter & Gamble Company)… but as @PhilGeis said Dr. Lochhead is an expert on the subject, I tend to believe more