-
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.
-
5 Replies
-
Can you give the full formula in %? It’s hard to troubleshoot without this.
-
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.
-
It happens - that’s why we do stability tests. Have you considered using a pH buffer?
-
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?
Log in to reply.
