Nikifarokhi
Forum Replies Created
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I mean a 20 volume hair color developer
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@chemicalmet thank you for your attention my question.
Firstly you may say, the pH of a hair developer must be between 4-5, am I right? Then you mentioned I use a pre-prepared/purchase a buffering system of, let’s say, phosphoric accid/phosphoric acid sodium and disodium salts, which have been prepared and adjusted pH 4-5 in advance? So the only thing I should do is adjust the pH of the product with this buffer and maintain it 4-5?
Secondly, with refrence to determination of shelf life, I read the patent below in whitch it explained that for determining whether the product is stable for one year I have to heat the weighed finished hair developer at 95’C for 24h and then measure the amount of h2o2 via titration, is it correct?
https://patents.google.com/patent/US8357356B2/en
patents.google.com
US8357356B2 - Stabilized hydrogen peroxide compositions and methods - Google Patents
A hydrogen peroxide-containing composition comprising at least one antioxidant and at least one free radical scavenger operable to neutralize reactive oxygen species generated by the hydrogen peroxide and a method for stabilizing hydrogen peroxide containing compositions.
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Totolly, would you advise me how a buffer system be made in a cream or… Especially by a trivalent acid?
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Hi
The percentages of the surfactants might be increased
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It is due to PQ10. Without it, the gel will become transparent.
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Dear Pharma,
Thank you for your advice in deed. It was really helpful. It is definitely something else as per your explanation. -
What I have the powder NaPCA, and can’t dissolve it in water. In boiling water it creates a cream-like solution. When I use polysorbate it becomes a translucent solution on the top of which is oli (I mean two phase are created), and with the passage of time, when the solution becomes cooler, the oil phase turns to the powder NaPCA:((
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Ok thank you for your kind advice.
Pharma said:I see.Now, in that case you’d need about 4 grams of citrate buffer. That is for medium hard tap water and for EVERY LITRE of water coming out of your shower and for every ‘scoop’ of shampoo you use during that particular shower session.As you can see, you don’t stand a snowball’s chance in hell maintaining a pH other than tap water. All you can do is dropping the pH in the bottle and for that, simply adding enough citric acid is all that’s required. -
Thank you so much for dedicating your time. Yes, you are absolutely right. Some surfactants dochange the pH of the solution. The reason I want to buffer my shampoo is to avoid the shampoo’s pH rising during rinsing with water whose pH is 7.
So your advice would be add some citric acid until the pH has become a little below 5 and then add alittle amount of NaOH (solution 0.1M for example) to reach the pH 5?Pharma said:Now you have me a bit confused…It is absolutely impossible to tell you how much you’d have to add, even if we knew the starting pH of your product. Many detergents have a pH above or below 7 and even then, they tend to act as buffers themselves. Sugar based surfactants as an example tend to have an alkaline pH (9-11) for stability reasons. Alas, we don’t know how much and what kind of alkali has been added to achieve said pH.The first and foremost question is: Why do you need a buffer? What and why do you want to buffer?From a scientific point of view, it is rather ridiculous to buffer a shampoo because it would require either too much buffer solution or the stuff is self-buffering and all you’d need to do is adjust pH. -
Pharma said:Given that you don’t use plain water but rather large amounts of soaps which may not be pH inert, calculating will only give you a hint (apart from the fact that calculating with polyprotic acids is a PITA unless you’re really good with maths or use an app). In the end it’s easier to just add citric acid and then start adding NaOH until you hit pH 5. That would also be a safer way than adding dry NaOH to the formulation and titrating downwards with diluted citric acid as you intend doing (unless I misunderstand your procedure).As a rough estimate which in practical regards is usually more than good enough, 1.5 mole equivalents of NaOH will bring a citric acid solution to a pH slightly below 5 (you could also mix equimolar amounts of citric acid and trisodium citrate to get the same result).
Thank you for your answer. I just need to know what you mean by “it’s easier to just add citric acid and then start adding NaOH until you hit pH 5″. Would you mean I need to add for example 1 cc citric acid 20% to 100cc of my shampoo to reach the pH below 5 and the and a solution of NaOH to reach the pH 5?
Can it make a buffer? since as far as I know to have a solution of citric acid without its salt and using a strong base instead for pH 5, citric acid should lose its two hydrogens out of three for the pKa ~5, but the mole strong base must be less than 2 to react with the acid and produce the conjugated weak acid salt.
So, if it is right, could you please tell me how much citric acid is required to go below pH 5 and adjust it with what molarity of NaOH? -
Another question is:
If the buffer is required, is it possible to buffer the solution with ammonium hydroxide and NaCl? I guess the buffer needs to maintain the pH in 6.8-7.2 -
Thank you so much for your response
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I’ve bought the product, it is on the market. I just don’t know whether there is a logic behind its manufacturing or it is just a manufacturing gaffe.
Could Granulation processing used in pharmacutical factories for producing tablets be applied?
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You are right, but I have had such a formula. Based on my experience, it is due to PQ10. I excluded it and the problem was solved. I do not know the reason. Maybe it is precipitated when using SCI.
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Thank you so much for your response.
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Thank you so much for your informative reply. I will try as per to your instruction
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Hi,
Thank you so much for your reply. Actually, our company wants to use some botanical oils such as milk thistle and black seed oil whose acid values are high due to the bad store conditioning of the seeds (after buying them for cold press proceture and use for edible oil, it is realized), in cosmetic products like creams. I just want to know the range of acid or peroxide values that is accpted to use in the cosmetucs. I know in the food industry these factors are determined, but in the cosmetic I am asking