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  • Precipitation and gel incompatibility salicylic acid serum

    Posted by Ms_Formulation on April 28, 2024 at 6:17 am

    Dear all,

    I am trying to formulate a salicylic acid serum.

    I have two problems :

    1. Phase B upon mixing yields a clear solution, but once mixed with A1, a white flaky preciptation happens and the sodium hyalouronate gel become thicker, like plastic gummy appearnce ( similiar to chewed gum, please excuse my metaphor)

    I use a stock of 2% sod HA to provide a 0.25% sod HA in the formula

    2. I cannot dissolve allantoin at all ! maybe there is something I am doing wrong, but I did a little experiment and it took approximately 100 mL of water (70 C) to dissolve 200 mg of Allantoin in presence of 2% urea.

    What might be causing this problem ?

    And should I use another gelling agent for thickenning the serum ?

    I hope you are not dissapointed with my limited knowldge, I have a phD and masters in oral drug delivery, but still a beginner in cosmetics formulation.

    the formula is as follows

    A1 Water 65.650

    A1 Xanthan gum 0.250

    A1 High molecular weight sodium Hyalouronic acid 0.250

    A1 Disodium EDTA 0.100

    A2 Sodium citrate 1.000

    A2 Urea 2.000

    A2 Allantoin 0.250

    A2 Glycerine 2.000

    A2 Sod Citrate 1.000

    A2 PEG 400 2.000

    B Propylene Glycol 19.000

    B Salicylic acid 2.000

    B Mandelic acid 1.000

    B Polysorbate 80 1.000

    C Chamommile extract 1.000

    C Grean tea leaf extract 0.200

    C Phenoxyethanol 0.800

    C Na benzoate 0.500

    Ms_Formulation replied 1 week, 3 days ago 2 Members · 2 Replies
  • 2 Replies
  • MarkBroussard

    April 28, 2024 at 3:18 pm

    Couple of issues:

    (1) Higher molecular weight HA and Xanthan Gum are generally incompatible. If you want to use Xanthan Gum, you’ll need to incorporate an HA less than 50kDA that won’t gel.

    (2) Allantoin: Incorporate it in water heated to 50-55 C. It will go right into solution. If you use more than 0.5% Allantoin and/or incorporate at temperatures greater than 55C, the Allantoin will precipitate out of solution.

    (3). Increase your solvent for the HA to 35%. You can cut back on the amount of Sodium Citrate to a 1:10 ratio of SC:SA. Heat the solvent to 70C or so and then add the SA.

    • Ms_Formulation

      May 9, 2024 at 10:13 am

      Thank you so much Mark, I will do as you suggested

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