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Working with Eumulgin SG in low-pH emulsions
Hello!
I’m working on an azelaic acid serum formulation emulsified with sodium stearoyl glutamate (Eumulgin SG).
phase a:
dipropylene glycol 20%
azelaic acid 7%
glycerin 7%phase b:
water 48%
gluconolactone 5%phase c:
capric/caprylic triglycerides 8%
cetyl alcohol 2%
eumulgin sg 0.5%phase d:
triethanolamine <1%
optiphen plus 1.5%
Phase A is heated until the azelaic acid is solubilized. It is added to Phase B and heated to 75°C, while Phase C is heated in the same water bath in a different container. The two mixtures are blended together before being left to cool. Then Phase D is added and pH is adjusted to ~4.0.I’m running into issues when the emulsion forms. It looks very smooth for a bit but then separates within minutes. I was able to save one batch with the addition of 1% aristoflex avc, but I’d rather not go that route due to aristoflex’s instability at lower pHs. I’d also prefer a milky fluid over a gel texture.
As far as I can see, AHA serums with Eumulgin exist, so I assume it’s fine with the pH. Can anyone who’s worked with Eumulgin tell me what might be wrong? Thanks!
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2 Replies
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I have worked with Eumulgin SG in a mineral sunscreen formulations. I think the main problem is total emulsifier in the formulations. Your oil phase is around 15-17%, and you will need 3.0-3.5% emulsifier. I will recommend going with additional non-ionic emulsifier either ethoxylates like oleth-15/ steareth-20 or you can use APG such as Coco-glucoside
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singhc10 said:I have worked with Eumulgin SG in a mineral sunscreen formulations. I think the main problem is total emulsifier in the formulations. Your oil phase is around 15-17%, and you will need 3.0-3.5% emulsifier. I will recommend going with additional non-ionic emulsifier either ethoxylates like oleth-15/ steareth-20 or you can use APG such as Coco-glucoside
Thanks so much for your input! A few more questions:
• I’m not really sure how my oil phase adds up to 15-17%. Isn’t it 10% from the triglycerides and cetyl alcohol?
• Unfortunately, one of the requirements for the formula is no ethoxylated ingredients (the TEA is just for testing, it will be replaced by sodium citrate or arginine). Do you think glyceryl stearate or sorbitan olivate may work?Thanks again!
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