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Vitamin C + Alpha Arbutin Serum - Stability Issue
I have prepared the following water base serum formulation: Ethyl Ascorbic Acid 8.0%, PPG 3.5%, Glycerine 2.5%, PEG 40 2.0%, D Panthenol 2.0%, Niacinamide 3.0%, Alpha Arbutin 4.0%, Phenoxyethanol 0.8%, Vitamin E 0.5%, Alantoin 0.1%, Aloe Vera 200x 0.05% and balance water.
Two months storage in ambient showed reduction in viscosity from 860 to 470 cps and in oven at 45 deg C, the viscosity reduced to 180 cps. The colour of serum also changed from initial Pale Yellow to Dark Brown.
I understand that Vitamin C serum tends to oxidize over time but the viscosity reduction is too much in two months time and may lead to consumer dissatisfaction in application. Any suggestions please.
Regards,
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10 Replies
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@AMS It is not clear what is described by “PPG” or even “PEG-40” and those polyols (we know what those acronyms mean) are your key thickening ingredients. E.g. PPG-15 Stearyl Ether + PEG-40 Stearate: now we have something to go on. That combo would produce a nice emulsion, BTW, one that is oxidatively stable as well. You might also use a Poloxamer PPG/PEG block copolymer to achieve 1000 cps sustainably. But alas…
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Thanks, PPG (polypropylene glycol) used in the formula. I have added now ferulic acid @0.5% and increased the level of Vitamin E from 0.5% to 1.0%. Hope this would help in keeping the viscosity stable. Any suggestion, look forward to.
regards,
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As @chemicalmatt mentioned, it’d be nice to have full INCI names for your ingredients. If PEG-40 is PEG-40 hydrogenated castor oil, then your Polypropylene glycol won’t probably be enough to give thermal stabilization of your viscosity.
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In my opinion, you should use gelling agents like xanthan gum or sodium hyaluronate. You can also consider using Alpha Tocopherol 1% plus Ferulic Acid 0.5% to increase stability of Vitamin C derivative. I have never used the combination of EAA and Alpha Arbutin before, so I am not sure about the interaction between this 2 materials.
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Ferulic Acid is show to stabilize ascorbic acid, not the derivatives.
Tocopherols are oil-soluble, so I don’t see how it should stabilize water-soluble active.
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Hi! have you found the reason why your formulation turner brown?
I have also prepared some samples of alpha arbutin serum. some of them also turned dark brown within 2-3 months.
formulation contains aqua, EDTA-4Na, alpha arbutin, niacinamide, licorice extract, hyaluronic acid, PG, phenoxyeyhanol.
may be the chelating agent is not efficient enough to do the job. kindly share your experience.
waiting for your kind suggestions.
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Maybe licorice extract darkens over time?
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2 samples without licorice extract also turned brown. But their pH was approximately 9; may be at high pH this color change occurs.
another sample tried by replacing 4EDTA with 2EDTA and hyaluronic acid with Covacryl AC, having same % of licorice whose pH is 6. This sample has not changed its color.
what is your opinion?
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The ph is soo important in formulation, you must know your adequat ph and compatibility with your ingredients.
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alpha arbutin also forms needle like crystals on walls of beaker. How can we solve this problem?
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