Ingredient Condition and Serum Formulation Stability (Hyaluronic Acid, Betaine, Allantoin)

Question

I have some Hyaluronic Acid Nano powder that has turned brown, although it's not expired. Also, my Natural Betaine crystals have clumped together and there's moisture on the lid. The expert mentioned these conditions are likely due to moisture but are still usable, except for the brown Hyaluronic Acid which shows some degradation. The Betaine clumping is normal due to its hygroscopic nature.

I would like to ask about the stability, pH, and other potential issues with the following formulation:

Phase 1 (aq1)
- สารสกัดใบบัวบก 5%
- water qs to 20%
Phase 2 (aq2)
- allantoin 0.8%
- glycerin 5%
- water qs to 20%

Combine aq1 and aq2 to make aq3.

Phase 3 (add to aq3)
- hyarulonic acid 1%
- sepicide 0.5%
Final Step:
- water qs to 100%

Are there any stability issues, pH concerns, or other problems with this formulation?

MySkinRecipes Expert · Accepted Answer

Expert Answer

Dear Customer,

Regarding the condition of your ingredients:

Hyaluronic Acid Nano (powder turned brown): The powder changing to a brown color is likely due to moisture exposure, which can affect the quality and effectiveness of the Hyaluronic Acid. Although it may not be expired, the color change indicates some degradation.
Natural Betaine (clumped crystals, moisture on lid): This characteristic is due to the hygroscopic nature of Natural Betaine, which readily absorbs moisture. This is part of its function in helping to retain moisture for the skin. Clumping does not mean it is spoiled; it can still be used as usual. It should be stored in a tightly sealed container to avoid moisture long-term.

Regarding the stability of the formulation you provided:

Allantoin: Using Allantoin at a concentration of 0.8% in water may not fully dissolve at room temperature, as Allantoin's maximum solubility in water is around 0.5% at 25°C. If you need it to fully dissolve, you might need to reduce the concentration to no more than 0.5% or use it with appropriate amounts of Natural Betaine or Glycerin to help increase solubility. (Your formula includes 5% Glycerin, which helps, but 0.8% might still be too high).
Centella Asiatica Extract, Glycerin, Hyaluronic Acid, and the ingredient functioning as a preservative (such as the Sepicide you specified): The other ingredients in the formulation are generally compatible.
pH Level: The pH of the formulation will be slightly acidic, which comes from the Centella Asiatica extract. This pH level is suitable for the skin.
Preservative: This formulation requires a suitable preservative to prevent microbial growth, as it contains water and natural extracts. You should choose a preservative that is compatible with the other ingredients and effective within the pH range of the formulation. Examples of suitable preservatives include Mild Preserved Eco™, PE 1090 Preservative, or Mild Preserved™ COS.

Hope this information is helpful. Please feel free to ask if you have any further questions.