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Understanding pH Buffers & pH Adjustments in Skin Care Formulations
Hello Everone,
I trust you are all well and keeping safe during these uncertain times.
Having had more spare time on my hand I have decided to revisit my old notes taken during my Cosmetic Science Diploma, in the attempt to better understand cosmetic formulation.
I am trying to understand how to go about stabilising the pH of a skin care formulation. From my old reference books I understand that one would use a pH Buffer to stabilise and maintain a products pH. These buffers consist of an acid such as Citric Acid and a corresponding base; in the case of Citric Acid you would use Sodium Citrate. My question is how, would you go about formulating with a buffer? Is there a set % you would require to use in order to have a obtain the desired pH? At what stage would you add the pH buffer?
For example, if I was formulating a Toner product that requires a final pH of 5.5 how might I go about achieving this pH and how might I stabilise said pH?
Apologies for all the questions but any help would be much appreciated.
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2 Replies
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There was a very recent post on this topic
https://chemistscorner.com/cosmeticsciencetalk/discussion/7475/how-to-use-buffers-in-cosmetics#latestBasically if you know what pH you want your formula to be you can select a buffer that has a range encompassing your selected pH. Citric acid should be fine for 5.5, and with a little base (sodium hydroxide would work well) you can create the sodium citrate in situ.
So make your toner and adjust pH at the end using a combination of your acid and base. You would then check the sample over a period of time to see if the buffer remains effective
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Thank you very much for your help EVchem.
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