Home Cosmetic Science Talk Formulating Microbial Challenge Test Protocols For Solid Cosmetic Formulations

  • Microbial Challenge Test Protocols For Solid Cosmetic Formulations

    Posted by MarkBroussard on March 31, 2015 at 6:14 pm

    I have searched trying to find microbial challenge protocols for products that are solids.  Anyone know what testing techniques are used?

    I am assuming it is probably a disc test on a petri plate, where a disc is created from the solid sample, but can’t find any definitive information on this.
    The_Microbiologist replied 9 years, 1 month ago 5 Members · 7 Replies
  • 7 Replies
  • Bobzchemist

    March 31, 2015 at 7:23 pm

    In my limited knowledge of how these tests are actually conducted, I am pretty sure that a blender was involved…but that’s as far as I can go.

  • MarkBroussard

    March 31, 2015 at 7:45 pm

    Thanks BobZ.  Perhaps the product is blended into a paste and and the paste is placed into the liquid agar growth medium and the plate is streaked with bacteria.  If there is no growth on the plate, the preservative is working.  Or perhaps the product is blended with the liquid agar and then plated.

    I am only familiar with the disc technique, but that is dated knowledge.

    May 1, 2015 at 10:35 pm

    @MarkBroussard Hi Mark, I am looking for someone to do some formulations for acne-prone care, do you offer a service for doing formulations? Could you send me an email: xie_shally@yahoo.com, let’s see what we can do. Thanks a lot.

  • Chemist77

    May 2, 2015 at 1:06 pm

    @MarkBroussard I was recently in Dow Microbial Lab and witnessed something about paints and their preservation over a period of years for microbial and algae growth. They used a  patch of paint in the middle of the dish and sprayed with microbes to be tested and separately with algae to check the efficacy of the preservative. 

    I don’t know how relevant it is for you but I guess this is how you would go about solids as well and as you mentioned by using a paste of it. But next time I am there I am gonna brig up this point just to make sure. 
  • MarkBroussard

    May 2, 2015 at 1:12 pm


    Thanks!  Very much appreciate the comment.  That is about the only technique that I can think of for solids.
  • Chemist77

    May 2, 2015 at 1:23 pm

    Just an addition, they were doing four cycle challenge test and depending on the customer request they are willing to extend this period further. 

  • The_Microbiologist

    May 4, 2015 at 8:49 pm
    We run CTFA M-6 for atypical cosmetics.  There is some info on the linked page.

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