Comments on: How To Stability Test a Cosmetic Formula http://chemistscorner.com/how-to-stability-test-a-cosmetic-formula/ Cosmetic science resource site where you can learn all about cosmetic chemistry Thu, 09 Feb 2012 21:38:22 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: Perry http://chemistscorner.com/how-to-stability-test-a-cosmetic-formula/#comment-6723 Perry Sun, 22 Jan 2012 14:57:20 +0000 http://chemistscorner.com/?p=98#comment-6723 I don't understand your question. 45C for 8 weeks is supposed to be predictive of what RT for 1 year would be. It's not a perfect model but it's pretty good and good enough for most cosmetic formulas. Data that validates would be pH, Viscosity, color, and odor. Also, you should do 8 weeks micro challenge testing I don’t understand your question. 45C for 8 weeks is supposed to be predictive of what RT for 1 year would be. It’s not a perfect model but it’s pretty good and good enough for most cosmetic formulas. Data that validates would be pH, Viscosity, color, and odor. Also, you should do 8 weeks micro challenge testing

]]> By: Jorge http://chemistscorner.com/how-to-stability-test-a-cosmetic-formula/#comment-6718 Jorge Sat, 21 Jan 2012 23:45:37 +0000 http://chemistscorner.com/?p=98#comment-6718 Can you elaborate on the 45C for 8 weeks? What data validate? Do you recommmend for bith chemical and microbiological accelerated stability testing? Can you elaborate on the 45C for 8 weeks? What data validate? Do you recommmend for bith chemical and microbiological accelerated stability testing?

]]> By: Stephanie http://chemistscorner.com/how-to-stability-test-a-cosmetic-formula/#comment-6599 Stephanie Sun, 15 Jan 2012 15:58:29 +0000 http://chemistscorner.com/?p=98#comment-6599 Will check it out! Thanks, Perry! :) Will check it out!

Thanks, Perry! :)

]]> By: T. Sobisch http://chemistscorner.com/how-to-stability-test-a-cosmetic-formula/#comment-6577 T. Sobisch Fri, 13 Jan 2012 22:20:04 +0000 http://chemistscorner.com/?p=98#comment-6577 Dear Stephanie, you have to distinct between microbial/chemical stability and separation stability. Arrhenius applies to the first but not to the second. So in my view it is purely empirical and applies more or less. Temperature effect on separation stability is manyfold mainly influencing viscosity (creaming), Ostwald ripening through diffusion/solubility and effect of temperature on emulsifier polarity and phase diagrams. Titus Dear Stephanie,

you have to distinct between microbial/chemical stability and separation stability. Arrhenius applies to the first but not to the second. So in my view it is purely empirical and applies more or less. Temperature effect on separation stability is manyfold mainly influencing viscosity (creaming), Ostwald ripening through diffusion/solubility and effect of temperature on emulsifier polarity and phase diagrams.

Titus

]]> By: Perry http://chemistscorner.com/how-to-stability-test-a-cosmetic-formula/#comment-6576 Perry Fri, 13 Jan 2012 19:08:50 +0000 http://chemistscorner.com/?p=98#comment-6576 50C is really higher than you need however it does depend on the conditions which your product will ultimately be shipped in. If you sell a lot in Arizona during the sumnmer then it is going to need to be stable at 50C. But for most products, 45C would be enough. 50C is really higher than you need however it does depend on the conditions which your product will ultimately be shipped in. If you sell a lot in Arizona during the sumnmer then it is going to need to be stable at 50C. But for most products, 45C would be enough.

]]> By: Kim Smith http://chemistscorner.com/how-to-stability-test-a-cosmetic-formula/#comment-6575 Kim Smith Fri, 13 Jan 2012 19:05:57 +0000 http://chemistscorner.com/?p=98#comment-6575 I was wondering how important is testing in the 50c? We have a petrolautum base product with color in it and at 50c it seperates. Should we be concerned with this? Would the 45c test be enough? I was wondering how important is testing in the 50c? We have a petrolautum base product with color in it and at 50c it seperates. Should we be concerned with this? Would the 45c test be enough?

]]> By: Perry http://chemistscorner.com/how-to-stability-test-a-cosmetic-formula/#comment-6574 Perry Fri, 13 Jan 2012 18:27:55 +0000 http://chemistscorner.com/?p=98#comment-6574 Hello Stephanie, Indeed, I believe it was derived from the Arrhenius equation. I'm not sure of exact references but you can check the following for more information. 1. Eccleston GM. Application of emulsion stability theories to mobile and semisolid O/W emulsions. Cosmetics & Toiletries 1986: 101(11): 73-135 2. Rieger M. Stability testing of macroemulsions. Cosmetics & Toiletries 1991; 106(5): 59-66 3. Garrett, E.R. Prediction of stability of drugs and pharmaceutical preparations. J. Pharm. Sci., 1962, 51, 811-833 Hope that helps Hello Stephanie,

Indeed, I believe it was derived from the Arrhenius equation. I’m not sure of exact references but you can check the following for more information.

1. Eccleston GM. Application of emulsion stability theories to mobile and semisolid O/W emulsions. Cosmetics & Toiletries 1986: 101(11): 73-135
2. Rieger M. Stability testing of macroemulsions. Cosmetics & Toiletries 1991; 106(5): 59-66
3. Garrett, E.R. Prediction of stability of drugs and pharmaceutical preparations. J. Pharm. Sci., 1962, 51, 811-833

Hope that helps

]]> By: Stephanie http://chemistscorner.com/how-to-stability-test-a-cosmetic-formula/#comment-6573 Stephanie Fri, 13 Jan 2012 18:15:19 +0000 http://chemistscorner.com/?p=98#comment-6573 Hi Perry! Thanks for the great write up. "A handy rule of thumb is that a sample stored at 45C for 8 weeks is equivalent to one that is stored at room temperature for one year. This isn’t an exact predictor, but is good enough for the purposes of cosmetic products." Would I be correct to assume that this statement is based on the Arrhenius equation? Where an increase of 10C in temperature doubles the rate of a reaction? I was wondering if you could point me to some journals/articles that mention this? I'm currently doing my write up for my thesis and am not able to find any references for that statement. Your help would be greatly appreciated. Thanks in advance! Regards, Stephanie Hi Perry!

Thanks for the great write up.

“A handy rule of thumb is that a sample stored at 45C for 8 weeks is equivalent to one that is stored at room temperature for one year. This isn’t an exact predictor, but is good enough for the purposes of cosmetic products.”

Would I be correct to assume that this statement is based on the Arrhenius equation? Where an increase of 10C in temperature doubles the rate of a reaction?

I was wondering if you could point me to some journals/articles that mention this? I’m currently doing my write up for my thesis and am not able to find any references for that statement.

Your help would be greatly appreciated. Thanks in advance!

Regards,
Stephanie

]]> By: Zoheb http://chemistscorner.com/how-to-stability-test-a-cosmetic-formula/#comment-6483 Zoheb Sat, 07 Jan 2012 05:41:26 +0000 http://chemistscorner.com/?p=98#comment-6483 Thank you very much perry. Thank you very much perry.

]]> By: Perry http://chemistscorner.com/how-to-stability-test-a-cosmetic-formula/#comment-6445 Perry Wed, 04 Jan 2012 13:04:01 +0000 http://chemistscorner.com/?p=98#comment-6445 Hello Zoheb, I'm not certain of this answer but this is my guess. 1. The reason you have samples at 25C for 12 months is because one year stability at room temperature is the standard goal. Going for less time at room temperature will give you no indication of how stable a product will be at one year. 2. The reason to go 30C for 6 months is because it is generally believed that this accelerated conditions will predict what will happen to the sample if it was held at RT for 1 year. Higher temperatures initiate chemical reactions that may have occurred over time. 3. The reason to go 40C for 6 months is the same as the 30C except for 40C, it will be predictive of 1 year stability after 3 months. If you go for 6 months it will be predictive of stability for 2 years. That would be my guess. Hello Zoheb,

I’m not certain of this answer but this is my guess.

1. The reason you have samples at 25C for 12 months is because one year stability at room temperature is the standard goal. Going for less time at room temperature will give you no indication of how stable a product will be at one year.

2. The reason to go 30C for 6 months is because it is generally believed that this accelerated conditions will predict what will happen to the sample if it was held at RT for 1 year. Higher temperatures initiate chemical reactions that may have occurred over time.

3. The reason to go 40C for 6 months is the same as the 30C except for 40C, it will be predictive of 1 year stability after 3 months. If you go for 6 months it will be predictive of stability for 2 years.

That would be my guess.

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