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pH drop in emulsion
What would cause a pH drop by about one point in an emulsion? It is stabilized by carbomer/TEA. Is this a sign that it is destabilizing? All other parameters are in spec.
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6 Replies
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Can you give the full formula in %? It’s hard to troubleshoot without this.
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Hmm, a pH drop in an emulsion stabilized by carbomer/TEA could be concerning. It might indicate some underlying issue like ingredient degradation, microbial contamination, or loss of TEA. Even if everything else seems in spec, it’s worth investigating further to ensure the stability and effectiveness of the product
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Check the microbial profile, it brings the pH down if there is any contamination. Or maybe the acid component/carbomer of your formula was not completely neutralized and now on standing the alkali has reacted with acidic components bringing the pH down.
I cant think of 3rd reason without knowing formula profile. -
Hi All! Sorry I wasn’t able to get back to you until now. Here is the breakdown of the fomrula:
Acrylates/C10-30 Alkyl Acrylate Crosspolymer 0.1 (not actually a carbomer)
Arnica Extract 0.1
Cetearyl Alcohol & Polysorbate 60 6.0
Polysorbate 80 4.0
Methyl Salicylate 10.0
Vanillyl Butyl Ether 0.4
Glyceryl Stearate 3.0
Isopentyl Diol 2.0
o-Cymen-5-ol (preservative) 0.1
Ethylhexylglycerin (preservative) 0.75
AMP (sorry - not actually TEA!) 0.09
The formula started out at a pH of about 7, and over 2 months has dropped to about 5.7. I don’t understand.
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It happens - that’s why we do stability tests. Have you considered using a pH buffer?
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That is my next step, Bob. I was just wondering if anyone has seen this type of thing happen in an emulsion, and is a pH drop like that a destabilization route?
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