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Stability of ascorbic acid
Hello,
Is it possible to stabilise l ascorbic acid with propylene glycol? I saw this serum and I’m really curious.
https://montarboskincarestore.com/vitalizing-vitamin-c-serum-12/#product-reviewsI red a study on Google docs that you can stabilise laa with just propylene glycol by warming it and stirring for 15 minutes.
Any ideas?? -
14 Replies
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No.
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If that were all it took then what were all those other companies wasting their time on?
Propylene Glycol might be better than an aqueous-solution in terms of stability but no I don’t think it would really prevent LAA oxidation, it will still degrade on its own, it will pick up water from the air too.
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you can solubilise, i.e. dissolve it in propylene glycol, but that will have no effect on its (lack of) oxidative stability
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What about airtight container?
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No. It’s always no.
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Learnt ferulic acid helps to prolong its shelf life for a bit longer than normal
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Just keep in mind C, E and ferulic combination is patented.
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I like how Belassi gives the replies straight to the point without other ways of interpretation and I totally agree with him.
You can improve the stability of ascorbic acid, if you increase the pH to 5-6.5.
What about using ascorbate salts? -
@em88, the optimal absorbtion of LAA by skin happens at a concentration of 20% and pH around 3. As far as I understand it will not do the job at pH of 5.
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If the product is for personal use, I would say that LAA serum can be stored in the fridge for 7-8 weeks in airtight container withough any signs of oxydizing. I make tiny batches for myself and keep it in the fridge. Regading the commercial products, check out what Clinique did:
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(comment is already mentioned) -
@ngarayeva001 What testing did you perform to get an oddly specific refrigerated shelf life of “7-8 weeks?”Honestly, again getting fixated on the L-ascorbic acid vice one of the more stable derivatives is a huge compromise if stability. -
@Microformulation my understanding was that change of the color (even minor) means oxidation. I left 20% solution in the room temperature under a direct light and it started changing color after 9 or 10 days. The same solution (same batch) stayed absolutely clear for about two months in the fridge. The Institute of personal care science also suggested that change of color means oxidation (may be they are not a legit source). I personally used many different vitamin C serums before I started formulating and saw them changing color pretty quickly (some already were yellow when I opened them). Please let me know if observation of the color isn’t sufficient. Again I am not suggesting that derivatives are not good enough, and I am using MAP in some of my serums. I just know that 20% LAA makes skin brighter after just a couple of weeks of use. Frankly, I have not seen such a result even after 1% of retinol. This is the reason why I believe that the product above (or making small batches) might be a good idea.
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Also, regarding derivatives, there are studies that suggest that MAP is only effective at a concentration of 10%
Source: Photochemistry and Photobiology, June 1998, pages 669–675; and Journal of Pharmaceutical and Biomedical Analysis, March 1997, pages 795–801
As per my expenrience, it is extremely difficult to dissolve more than 5% of MAP even in a hot water (I don’t know if it’s possible with professional homogenizers). Even at 5% it gives quite an unpleasant feel to serums (it feels like a film on a skin). It also tends to cause change of color of a product if pH is below 7 (suppliers say 6, but my own experience says 7), which is not very desireable as skin’s pH is on the acidic side and lower than 7. My point is, there is a good reason why many try to stabilise LAA. There are manufacturers in Asia who make LAA serums on demand and ship it by express mail, so it reaches the customer within just a couple of days after it was manufactured. The Ordinary suggests to use LAA powder and mix it into another product. I disagree with this approach because unless it comes with a precise scale and pH strips it is impossible to get the right concentration and pH. I am not suggesting that derivatives are bad, however LAA is obviously better.
Disclaimer: I am only commenting on brightening properties of LAA thus compared it with MAP (which has proven brightening properties).
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