• Formulating

  Tetrasodium Glutamate Diacetate and Citric Acid

  Posted by Aniela on July 17, 2025 at 1:06 pm

  Hello,

  I was revising all my notes on chelating agents (from this forum and elsewhere), and found two comments on its better functionality with citric acid: @Pharma said “…best used in combination with a small amount of citric acid.”, and @MarkBroussard said “Readily biodegradable and when combined with citric acid really boosts the performance of preservatives.”.

  Could you explain, please, what “a small amount” means? Does it relate to the quantity of GLDA used?

  I should specify that I’ve always used only Lactic acid to lower the pH of my formulations.

  Thank you.

  Aniela replied 1 month, 1 week ago 3 Members · 6 Replies
• 6 Replies

• 

  ketchito

  Member

  July 18, 2025 at 8:27 am

  Tetrasodium glutamate diacetate has 4 possible groups available for chelation (they are carboxylic groups). The idea is that you go as high on pH to have them deprotonated. The best performance is actually at a pH over 9, but that’s not a normal pH of a cosmetic (same cas if you want to at least have 3 deprotonated groups, which require a pH above 6). Now, at a pH of above 4.5-5.0, you at least have two deprotonated groups, which is ok (not great, but ok). Citric acid can work as a weak chelant, and it happens that at a pH above 5.0, it also has 2 groups deprotonated. That’s why it can help bosst Tetrasodium glutamate diacetate. Unfortunately, lactic acid is not as useful since it only has one carboxylic group.

  • 

    Aniela

    Member

    July 18, 2025 at 1:13 pm

    Thank you for such a detailed explanation.

    I’m on the fence about the trade-off, though: do I really have to stop using lactic acid in all my formulations? Or should I use the GLDA and citric acid combo only in the more “vulnerable” formulations?

    • 

      ketchito

      Member

      July 19, 2025 at 8:37 am

      You could use both citric and lactic acid (many formulas for hair do, just check on the new Elseve formulas, especially the ones for shine and damaged hair…there’s a very nice strenghtening effect from the use of organic acids based on scientiffic evidence).

      • 

        Aniela

        Member

        July 21, 2025 at 6:37 am

        Thank you. I’ll take a look.

• 

  Abdullah

  Entrepreneur

  July 18, 2025 at 12:20 pm

  I suggest 0.5% citric+ 0.05% GLDA for combination of these two. It will give a good buffer to at your desired pH.

  • 

    Aniela

    Member

    July 18, 2025 at 1:03 pm

    Thank you, Abdullah.

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