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Need some help with preservative choice!
Hi Chemists corner! I am new to cosmetic formulation and have been reading all cosmetic science papers I can get my hands on. I finally decided to make my own product, but have been experiencing some difficulties with the preservative choice. I want to make a water based toner/mist that contains panthenol (sorry for the format of the image) with pH 5.5 :
I did not really want to use any formaldehyde releasers and (although I don’t really mind) parabens as my mother does not use products that contain them. So that excludes Germaben II-E (INCI: Propylene Glycol, Diazolidinyl Urea, Methylparaben, Propylparaben), germall plus and phenonip (INCI: Phenoxyethanol (and) Methylparaben (and) Ethylparaben (and) Butylparaben (and) Propylparaben (and) Isobutylparaben). I looked into
Optiphen (Phenoxyethanol (and) Caprylyl Glycol) but it did not have adequate fungi protection and the caprylyl glycol is not very water soluble and my toner is a very aqueous system. The pH I want is too high for sorbic acid, so
I was thinking of using Geogard 221 (dehydroacetic acid and benzyl alcohol) with a bit of an extra fungus preservative as dehydroacetic acid can be inactivated by proteins and I don’t have access to Optiphen nd ( INCI Phenoxyethanol (79% to 81%),Benzoic Acid (11.5% to 12.5%) Dehydroacetic Acid (7.7% to 8.5%) ). Would geogard 221 and potassium sorbate work at pH 5.5? Would it be enough for my nutrient soup? I can list the preservatives I have access to if needed. Would the inclusionof a small % of ethanol help? Thank you so much in advance! -
13 Replies
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pH 5.5 is also too high for potassium sorbate, as it is the potassium salt of sorbic acid and it needs an acidic pH to convert to the acid form to be active.
Geogard 221 does work at pH 5.5, but you do need something extra on fungi.
I think pH 5.5 is also too high for benzoic acid.
Maybe phenoxethanol + ethylhexylglycerin is an idea.
There are more organic acids (Dermosoft 1388 (sodium anisate/sodium levulinate + glycerin) by dr. Straetmans, but your pH is also too high for that, pH 5 is recommended, below 5 will give precipitation). Dermosoft 1388 on its own also isn’t strong enough, pair it up with glyceryl caprylate or caprylyl glycol (use a solubilizer in an aqueous system)
I don’t think adding a small % of ethyl alcohol is gonna help much preservative-wise.Too bad you can’t use parabens. I’m so glad I’ve found a supplier that sells Phenonip. Finally no more trouble with my pH not being acidic enough for benzoic and sorbic (salts). Long live parabens.
Why don’t you want to use formaldehyde releasers? They’re very effective. And not such a royal pain in the b*tt to work with (pH too high or too low etc etc), I wish I could get them here… -
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@Doreen81 thank you so much for your answer. The reason for don’t wanting to use formaldehyde releasers is the same as the parabens, I re-read it and I should have worded it better (sorry english isn’t my first language). Would Chemikons (INCI: 2-phenoxyethanol, Ethylhexylglycerin) be enough?
@Microformulation Did you mean that dehydroacetic acid targets fungi? Because I knew it, I just thought that because I use panthenol and proteins can deactivate it I should add something extra. Sorry if that was not what you meant. Or maybe I am wrong about the proteins. I just kept reading things and taking notes so now I am not sure where I got this information. Let me have a few minutes to find my source!
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1. The ideal pH for organic acids is 4-5.5. As they become acidic, they become less soluble. If I recall correctly the ideal pH for potassium sorbate is 4.4
2. I have never heard of Panthenol or proteins deactivating an organic acid preservative system.When in doubt, look at some of the distributor supplied documentation from companies such as Lonza or Schulke.
https://drive.google.com/file/d/1Io-EqAUDY12dDql2s772za0a2c-N0Lmu/view?usp=sharing
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Thank you @Microformulation ! I think this was the post that talked about proteins and organic acids: http://swiftcraftymonkey.blogspot.pt/2010/10/preservatives-optiphen-nd-or-rokonsal.html?m=1 I will try to find references in academia. So at pH 5.5 the Geogard 221would be fine?
And yes, potassium sorbate works better at pH lower than 6. I think at 5.5 it’s only 30% effective but I was adding it just as a precaution.
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I have never heard of Panthenol inactivating an organic acid.
TDS of Geogard 221. Lonza endorses it for a ph between 2 to 7.
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Thanks @Microformulation ! I will try to formulate with it then and report results. I feel a bit confused when there is too much information, I think I will create a table for future comparisons. Would you mind telling me if that picture you posted earlier is available online and for other preservatives? The information is really neatly explained.
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https://drive.google.com/file/d/0BwuqL_fQzYhicDdwc1RieW9KZ3c/view?usp=sharing
It is from a Presentation that David Steinberg gave to SCC. David is a well know expert and author in this area as well as Regulatory.
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Note: I was confused when writing this. Panthenol is an alcohol and the proteins I was talking about (silk, why I thought the panthenol was it I will never know) I ended up removing from this final formula. So I seem to be talking about something that does not make sense. I guess I need to go clean up all the notes I have because I’m making a mess.
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You’re very welcome!
Dehydroacetic acid works on fungi, but I remember Geogard 221 not being very strong on it and should be paired up with something like sodium benzoate, here is the link where I got the information about Geogard 221.
Good luck!
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Optiphen Plus (Phenoxyethanol (and) Caprylyl Glycol (and) Sorbic Acid) works well below pH 6.
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Do you think the caprylyl glycol would be soluble enough for this without adding any emulsifiers?
I didn’t really look at optiphen because I couldn’t find any suppliers near me -
@Sissi99
You have to add a solubilizer if you use caprylyl glycol in an aqueous system.
Instead of using Optiphen Plus you can also look for the single ingredients.
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