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Dissolving sodium benzoate in glycerin
Would sodium benzoate be ruined (somehow) by dissolving it in glycerin that has been heated (5-30 second bursts) in a microwave oven?
I did the above so I could dissolve the sodium benzoate for a toothpaste I was making, and then I wondered if maybe I had ruined the sodium benzoate due to my ignorance.
There was NO bubbling of the glycerin, and the sodium benzoate dissolved nicely in the warmed glycerin by swirling & a little stirring with a whisk.
BEFORE YOU ASK: There is not much water in my toothpaste, THUS my dissolving the sodium benzoate in the glycerin.
Thanks for any help!
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14 Replies
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I don’t think you should have any issues. what is max temp you estimate?
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Happy New Year, Phil- and sorry @Margaret for hijacking😇
Would you be so kind to shed some light on the use of sodium benzoate in an usually alcaline (toothpaste) product? (except the whitening toothpastes, which I assume are acidic)
Thank you.
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This reply was modified 1 month ago by Aniela. Reason: spelling mistake
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This reply was modified 1 month ago by
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I was not notified of replies though I did TICK the appropriate box, sorry for not noticing the response!
I merely heated the glycerin in a measuring cup in a microwave on high for maybe 40 seconds total, in burst of 10-15 seconds each, then stirred the sodium benzoate/glycerin solution between heating. I did NOT take the temp., since I did not think of it (doh!). It DID dissolve nicely in the glycerin, and there was no discoloration or obvious changes I could see with my little eyes.
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1. Solubility of sodium benzoate in water is 1:1.8, so surely you don’t need much water in there, but it might be of no use in your product, because
2. It is relatively inactive above approximately pH 5. Sodium benzoate has both bacteriostatic
and antifungal properties attributed to undissociated benzoic
acid; hence preservative efficacy is best seen in acidic solutions
(pH 2–5). In alkaline conditions it is almost without effect.- as far as I know, a toothpaste should not have an acidic pH.Both (info) from the “Handbook of Pharmaceutical Excipients”.
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Same constation about ph of tooth paste almost are basic however we can find a lot of them contain sodium benzoate so how use it is preservative for toothpaste ph range?
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I did notice that as well, but I assumed that sodium benzoate was only used in the “whitening” ones- they should be acidic (I think) to be able to clean so deep.
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My I will check the pH of mine and tell you but I guess even whitening tooth paste are basic”i know that acidic pH is more efficient for limestone… “
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Indeed. Acidic pH is good for bacteria that causes cavities, so I would be surprised to find acidic toothpaste
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Hi,
According to this, there are some acidic ones, or there were- the article is from Sep. 2000
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Happy New Year!!
Benzoate’s effective pKa can be uncreased with some surfactants such as SLS - efficacy up to and > 7
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Thank you, indeed.
Didn’t know that about sodium benzoate’s behavior.
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Sorry -meant increased (not uncreased).
and I’ve noted this in preservation of surfactant-based personal products - shampoos, hand wash
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Thank you for the article, and no worries- somehow, my brain read “increased”.
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@PhilGeis thanks for the interesting add, first time I hear about that.
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