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Is this formulation likely self-preserving?
I understand that any preparation with a pH less than 4 presents a challenging environment for microbes to grow in.
On that basis, if I have an AHA BHA toner with a pH of 3.5/3.6 and 10% ethanol, is this recipe most likely self-preserving?
Thank you.
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10 Replies
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It could be, by why take the chance by not adding a preservative?
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Unlikely.
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@PhilGeis
why would you say unlikely? -
Because there are things that can grow at that pH
Because 10% ethanol is not preserving
Because you don’t know how much microbial exposure the product will experience
Because you don’t know the storage & use conditions of the product
Because lots of reasons.why not just add a preservative?
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As Perry said.
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it depends on titratable acidity more than the pH itself; from my experience, the lowest level of acidity at which I’ve observed consistent self-preservation is around 25-30 mg KOH/gover several years we made dozens and dozens of batches of this product, and others with higher acidites, and never had microbial growth in a single one -
The only way to know for certain is to test your product. Not knowing what else is in it … I am assuming you are using a chelating agent?
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Testing is not enough. The USP51-types whatever the pass/fail are not validated to anything.
Every recalled product passed the test.
Folks should design a preservative system that should work and confirm it passes. -
@PhilGeis that’d be ISO 11930, which is a lot more rigorous than the USP/BP challenge test
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@Bill_Toge
The tests are effectively the same - some have more demanding criteria.
None is validated. Anything less than complete elimination of all but 16404 at 1st time point is suspect by any protocol.
In anmy case, testing is not enough - one must consider manufacturing, packaging, stability and anticipated consumer use.
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