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Passed PCPC, now onto HRIPT
Things are going a little slower than I would have wanted due to family things, but the microemulsions I’m making just passed the PCPC test, which is excellent news. No traditional preservatives used either, which is more of a limitation of the formula rather than a deliberate choice. Now we’re getting ready for HRIPT testing and we’ve already selected a facility for this test.
I’ve since had play around with about 3% of my formula to keep it temperature stable. The microemulsion has been stable at room temperature for 9 months so far, but it fails in 2 days at 40C. Likely hydrolysis of the glycerides, but my tweaks have made it stable at 1 month so far. It’s a different system at 40C, and 3 months at 40C doesn’t translate to 1 year at RT. However, it’d be convenient to pass accelerated stability testing. It’d also be nice for it to be stable if people take it to the beach, leave it in their cars…etc.
We’ve also designed a cool glass bottle and package, contracted with a bottle manufacturer overseas to produce it, and will receive the first glass bottles soon. We contracted with a new cosmetic manufacturer to formulate an R&D batch of our formula, and they’re starting this week. We’ll have them send samples out for new PCPC and HRIPT testing since their formula is what would actually be sold. They will also do stability testing in house with the new bottles. I still need to find someone who can paint a label on glass with complex topography. Our capital raise starts in a month or two. No questions to ask, just posting some updates!
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9 Replies
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If you haven’t passed stability, it might be premature to go to HRIPT. Also, any formula changes you make should require a repeat of the micro testing too. You’ve got to have a stable product first.
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We’ll be repeating the PCPC with the modified formula using the R&D batch that the manufacturer will make this week. While I can formulate at home, we’re planning to have all official tests conducted using product made by an independent manufacturer. This way we’ll have a paper trail from the manufacturer to the testing facility with a record of ingredients and percentages from an independent party.
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PCPC test - can you be more specific?
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PCPC stands for Personal Care Products Council. The PCPC test is the most difficult PET to pass. It uses 10 times the number of bacteria as the ISO 11930 and USP<51>, similar concentrations of other organisms, and has more difficult passing criteria (e.g. greater log reduction after 7 days).
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Thanks for clarification - I understand the test and a member of the committee responsible for it.
Do NOT go off happy it passed “unpreserved” - it is preserved but how?. There is a reason and you need to confirm the WHY and confirm that the WHY will be in every product you make through stability. It might be a preservative or impurity in a raw material that the supplier may not maintain, some unique combination of ingredients and process that is not controlled.
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Thanks Phil, I’ll add that I do preserve the formula, just not with the typical parabens, phenoxyethanol…etc. I systematically tested the impact of each antimicrobial component with 9 separate screenings with pooled microbiota.
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Sounds good. Just be sure to understand and control
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The preservative efficacy questions I’ll leave to @PhilGeis and @Perry44 but I can weigh in on your thermodynamic stability issue. Most microemulsions will experience a change of state around 40 - 45C, and when that happens the test flies out the window. Same holds true with w/o and w/Si invert emulsions. These are intrinsically unstable at mildly higher temps, but quite stable at RT. I’ve had microemulsions and invert emulsions stable for >8 years, but they would have disassembled at 40 - 45C.
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Thanks Matt, that’s extremely useful information. I heard from a couple researchers that things get a little weird when you hit 40C for microemulsions, particularly those with ethoxylated surfactants and the types of oils that I’m using. However, I have managed to keep the formula stable at 40C for 1 month so far with some slight tweaks. I doubt it’ll be stable for 3 months.
What I ultimately want is the ability to put an expiration date on the product and not wait an entire year to do this. Maybe I can consider longer tests at 30 or 35C? If it lasts for 1 month at 40C, can you say that it has an expiration date of 3-4 months? (I forget the actual conversion). I know that it undergoes a change around 40C, but I’d still feel comfortable with such a label because I know it will be a conservative estimate.
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