Wednesday, November 3, 2010

Preservatives: Inactivation of preservatives by non-ionic ingredients

I mentioned in the parabens post that some preservatives - mostly the parabens - can be inactivated by non-ionic ingredients, including some of the fatty alcohols (like cetearyl alcohol), fatty acids, esters, and polysorbates, when they're used as emulsifiers (using the HLB system). The paraben based preservatives include Phenonip, Liquipar, and Germaben II, and the study to which I'm referring tested Phenonip at 0.3% in various non-ionic ingredients. (Liquipar PE and Germaben II aren't affected by non-ionic ingredients.)

Polysorbate 80 is the worst culprit, and at 2.5% in an emulsion it completely inactivated Phenonip! Polysorbate 20 partially deactivated it at 2.5% and 5.0%. Cetearyl alcohol and glyceryl stearate had no effect at 2.5% and 5.0%. Ceteareth-20 caused no problems at 2.5% but completely deactivated Phenonip at 5.0%.

So what do we do here? Obviously we can use other preservatives for products containing those ingredients or we could add another preservative to boost the efficacy of our parabens. And we can make sure we're using our ingredients at the right levels in the right products.

Join me in about an hour for inactivation of preservatives by pigments!


Naomi said...

Oh no! So, if I wanted to include Poly80 or 20 into anhydrous products, say sugar scrubs, then which preservatives can I use? Or what sub for the polys can I use - does cromollient sce inactivate preservatives too?

Thank you for this series on preservatives! So informative.

Susan Barclay-Nichols said...

As far as I know, Cromollient SCE doesn't inactive preservatives, so that's a good choice, and you can use e-wax or Polawax as your emulsifier in the scrub. (Have you tried an emulsified scrub with BTMS or e-wax? They're really lovely and creamy!)

I know this information came as a bit of a shock for me. I use liquid Germall Plus and Phenonip as my two main preservatives, and although I don't use the polysorbates in much (mainly fragrance sprays and cleaning products), it really took me by surprise!

Naomi said...

Shocking indeed!!! I usually put poly in my sugar scrubs for feet (I make your emulsified sugar scrubs for body - no poly) so that it rinses off cleaner. What about red turkey oil (sulfated castor oil inci: Ricinus Communis (Castor) Seed Oil)?

Angela said...

I am so glad I read your blog!! I am trying to formulate an easy tinted lotion recipe to use for a foundation. I ofcourse was thinking of using iron-oxides. My perservative of choice has been optiphen Plus. I don't see it on any of your lists. It contains Phenoxyethanol (and) Caprylyl Glycol (and) Sorbic Acid. It does say on the website that it is effective at pH 6.

Would this new information apply to my preservative of choice?

Susan Barclay-Nichols said...

Hi Angela. Here's the post on Optiphen Plus.

Florencia Taravella said...

Hello Susan!

My name is Florencia. I´m from Argentina. For a while now I´ve been reading your blog and let me say I love it!
I´m having some problems regarding phenonip in my formulations. After a series of experiments I got to the conclusion that adding the preservative in the heated oil phase, completely cracks the emulsion. (Already tried also adding it by parts to both heated phases, before mixing, and couldn´t get it right either). The only possible way, it seems, to get the emulsion right is to add the preservative in the cool down phase, lets say under 50C.
I have checked my ingredients, and none of them seems to be having trouble of compatibility or expiration date. I use a series of autoemulsionable waxes (beeswax, monoglicerol esters, mirysitic esters) and natural oils, such as almond and coconut oil.
I just don´t know what might be the problem here, do you have any suggestions for me? I´d really appreciate it because I´m losing my mind!
Thank you indeed!
Best regards

Susan Barclay-Nichols said...

Hi Florencia! Can you post your recipe in percentages with your exact process so we can figure this out. Does the lotion work when you don't use Phenonip? I ask because beeswax isn't an emulsifier without borax in the right proportions, so it's part of the heated oil percentage, not the emulsifier. Let us know!

Florencia Taravella said...

Hello Susan!
Thank you so much for your kind reply! What you told me rang me a bell...
I use approximately 9% of autoemulsionable waxes (I use Abesin E, which the supllier informs as being autoemulsionable);1% of cacao butter; 2% of liquid vaseline; 8% of a mixture of fatty acid esters and 7% of humectants (gliceryn and silicon).
I use 0,7% of phenonip and 1% fragrance. Maybe the amount of emulsionant is at its limit and these (preservative and perfum) crack the already formed emulsion when I add them.
Should I use borax??? I stopped using it once I started using these autoemulsionable waxes.

Thank you!!

Susan Barclay-Nichols said...

Abesin E is listed as a replacement for beeswax. What is it? Is it actually an emulsifier or a replacement for beeswax? Have you ever had this recipe work before? I have a feeling this Abesin E isn't an emulsifier...

Can you post your exact recipe and process so we can analyze it properly?

Florencia Taravella said...

Dear Susan:

I got in touch with my supplier and they informed me that Abesin is a replacement for beeswax and it needed to be used with borax. I first thought it was emulsifying.
However, I should let you know that this recipe has worked beautifully before, only when I add the phenonip in the cool down phase, and it actually is a very stable cream!! It seems like a miracle. This I attribute it to having so many different fatty acid esters in combination to the waxes.
However, I´m doing lots of experiments, barying in mind my oil phase required hlb, to improve the stability of the emulsion and not to deal with this phenonip problem again.

I will let you know my results!
Thank you so mch

Mama G said...
This comment has been removed by the author.
Mama G said...

Hi Susan,

If I use a beeswax/borax emulsifier, are there any preservatives that would be impacted by this? Thanks in advance!


Ronel Hendriks said...

Susan, a late question to this topic. I'm busy formulating mineral make-up (liquid foundation) that contains iron oxide, titanium dioxide and kaolin. I'm using Microcare PHG (2-phenoxyethanol+ Octane-1,2-diol) as an preservative. Would it have an effect on my preservative's efficacy if I add EDTA at 0.2%?

Susan Barclay-Nichols said...

Hi Ronel! Is there any indication in the data bulletin for that preservative that you can't use EDTA?

Shadi said...

Hi, How could we test if a preservative is inactivated? I am thinking of a routine test in stability procedures, rather than or in addition to microbiologcal challenge test.
Thank you