Home Cosmetic Science Talk Formulating Whats a good preservative to pair with Euxyl PE 9010

  • Whats a good preservative to pair with Euxyl PE 9010

    Posted by scelce on August 22, 2018 at 3:30 pm

    I recently got back my USP 51 (micro-bacterial test) results from the lab for my moisturizing creme. The results are indicating that my moisturizer is not meeting the passing criteria at day 14 because of the growth of gram positive bacteria in my formula.

    I’m currently using only Euxyl PE 9010 at .50% as my only preservative. Can anyone recommend any other preservative or ingedient I can pair with Euxyl PE 9010 to stop the growth of the gram positive bacteria? 

    If I bump it up to 1.00% would that solve my issue?

    Please help.


    Xanthan gum
    Allantoin Powder
    Sodium Lactate
    Oat Protein

    Organic refine Shea Butter 
    Organic Sweet Almond oil 
    Organic jojoba Oil clear 
    Organic Sunflower oil 
    Behenyl alcohol 
    Cetereath 20
    Glyceryl stearate

    Euxyl PE 9010 
    Vitamin E
    Scent oil Combination 

    My ingredients are very simple and clean. I would like to have my paired preservative also very simple and clean. 

    Chemist79 replied 5 years, 11 months ago 7 Members · 20 Replies
  • 20 Replies
  • Sibech

    August 22, 2018 at 3:46 pm

    You haven’t got a lot to reduce the water activity, giving everything a good base in which to grow. Increasing the concentration would be a decent first step but not necessarily solve your issue. What is the pH of your formula?

  • scelce

    August 22, 2018 at 4:27 pm


    I don’t remember of, I can test for it later. Do you think the PH can be causing the issue? 

  • Sibech

    August 22, 2018 at 5:31 pm

    No, Euxyl has a wide range - but reducing the pH may improve the preservation.

    The choice of additional preservatives is limited based on pH - for instance most organic acids require a pH of less than 5.

    The quickest choice would be parabens (they are safe!)

  • scelce

    August 22, 2018 at 5:41 pm


    I’m trying to stay away from using parabens in the formula. I will use citric acid to get the pH in the 4-5 range and bump up the Euxyl PE 9010 from .5% to 1.00%. 

    Should the citric acid be counted as part of the 100% that make up the formula? 

  • Sibech

    August 22, 2018 at 8:15 pm

    Yes, the citric acid should be considered part of the 100%
    Bump it to 1% and retest, you could (if it isn’t too expensive for your budget) do one at a lower concentration (still higher than 0.5) to use as little as possible.

    Remember to produce in GMP, EUXYL PE 9010 reacts with the bacteria and therefore a reduction of the activity is to be expected.
    When it is used in heavily contaminated products loss of active ingredient must be taken into account

  • Bill_Toge

    August 22, 2018 at 8:26 pm
    as a rule I’ve always started at 1.0% regardless of pH, and have only had it underperform twice (out of 5-6 dozen products)
    @Sibech you’d need to increase the glycerine to 40% w/w or more for it to have a significant impact on water activity
  • Sibech

    August 22, 2018 at 8:32 pm

    @Bill_Toge Good to know!

    I was thinking more in the line of suggesting some other glycols, pentylene glycol for instance, not glycerin.

    The one time I had issues with Euxyl PE 9010 I added a bit more ethylhexylglycerin (can’t remember the concentration) and that did the trick.
    Unfortunately, that does not entail 5-6 dozen of products - Yet :D !

  • scelce

    August 22, 2018 at 8:37 pm


    Sounds great. How much room would you leave for the citric acid? I am assuming 1-2% should be fine since I’m using simple ingredients. I can subtract from the water phase.

    I’m new to making cosmetics. Although I had some success, theres still a lot I need to learn. I really appreciate your time and help.

    Besides the citric acid, can you recommend anything else to make this product better?

  • scelce

    August 22, 2018 at 8:41 pm


    I will adjust the Euxyl PE 9010 from .5% to 1% and also reduce water phase by 1-2% and add 1-2% citric acid at cool down to see if it fixes the problem. Do you have any other recommendations to improve formula? 

  • Microformulation

    August 22, 2018 at 8:47 pm
    Keep in mind that Schulke recommends that you use PE9010 with a chelant.
    In addition to that, I would look at using a Glycol to decrease water activity.
    What is your packaging? The more secure the packaging the better. Jars are the worst on that spectrum.
    Lastly, examine you lab procedures. You should be mirroring the cGMP standards that exist in a credible manufacturer with your own cGLP sop’s.
    As someone, I greatly respect said, “The best preservative is ultimately good cGMP.”
    You have a leave-on product. As such be sure to look at appropriate levels for a leave-on product. Simply increasing to 1% may put you over those limits.
  • belassi

    August 22, 2018 at 8:48 pm

    Add 0.2% EDTA

  • Sibech

    August 22, 2018 at 8:49 pm

    @scelce if you want to reduce the pH don’t just add the citric acid in bulk.

    I don’t know how precise your balance is, but by the sound of it you would likely be better off making a citric acid solution, then slowly adjust with the solution until the desired pH and add water for the remaining percentage.

    As for making the product “better”, I can’t come with a lot of suggestions as I don’t know how your formula performs.

  • scelce

    August 22, 2018 at 8:59 pm

    are you talking about Disodium EDTA at .2 to help the preservative system? 

  • scelce

    August 22, 2018 at 9:01 pm

    Can you recommended a good glycol that performs well in cremes. 

  • Microformulation

    August 22, 2018 at 9:09 pm
    That is a pretty basic question. Generally, we see Glycerin used. However, you can buy Ethylhexylglycerin separately (Sensiva SC50) to use as well. Essentially an elegant Formulator will also use this as an opportunity to increase the moisturization as well. I use a lot of Glycerin/Zemea and Glucam (Lubrizol) for this shared function.
    What glycols do you have in stock?
  • Bill_Toge

    August 22, 2018 at 10:19 pm

    @Sibech 1,2-glycols are microbistatic (or at high enough concentrations, microbicidal) due to their chemistry, and the effect increases with carbon chain length - this is why they have a preservative effect, nothing to do with water activity

  • MarkBroussard

    August 23, 2018 at 1:19 am

    You’ll only need about 0.2% Citric Acid to get your pH down in the 5.0 range.  You could supplement that with EDTA, Phytic Acid or any other chelant.  Increase the Euxyl to 1% and throw in perhaps 0.5% Capryl Glycol or EHG/Caprylyl Glycol blend … that should do the trick.

  • scelce

    August 23, 2018 at 12:32 pm

    Thank you so much @Bill_Toge @MarkBroussard @Microformulation @Belassi
    @Sibech for your help. I will implement all your suggestions and let you know how it went. 

    Does anyone know if it’s true that Schulke will conduct a free 28 days microbial test if you use their preservative (Euxyl PE 9010 ) in your formula?

    You just covered basic shipping and handling fees? 

  • Microformulation

    August 23, 2018 at 12:49 pm

    Yes, Schulke will do the testing if you use their product. Contact them or your rep for the shipping details.

  • Chemist79

    August 25, 2018 at 11:00 am

    Bump it up and try both 0.8 and 1.0%, I find PE 9010 to be a bit temperamental at levels of 0.6 or lower

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