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Nitrosamine
Given a situation where DMDM Hydantoin is used with Triethanolamine and the pH is around 6.5-7, is there a possibility of nitrosamines formation???? As I understand it would take a nitrite and a secondary amine to produce a nitrosamine with a pH below 6, am I correct in my approach or is there anything which needs to be added or edited???????
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18 Replies
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regardless of pH, there is no possibility of nitrosamine formation here; DMDM hydantoin is not a nitrite or a nitrite precursor, and triethanolamine is a tertiary amine (so it couldn’t become an N-nitrosamine even in the presence of nitrites)
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@Bill_Toge
Thanks Bill I was just wondering that only, was a bit concerned about the tertiary one too. -
no worries, glad to be of assistance!
to the best of my knowledge, the only thing apart from sodium nitrite that a) could generate nitrosonium ions (the reactive species responsible for nitrosamine formation), and b) is generally approved for use in cosmetics, is bronopol; you’ll be fine using DMDMH, no matter what amine you use
(I researched the gory details of this subject a few years back, when someone senior in our marketing department read something about nitrosamines, and got themselves into a huge panic about it)
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Hehehe we had a similar issue few years back with Imidazolidinyl Urea and Triethanolamine, but we are still safe.
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Am I correct to say that I can safely assume that Urea (Yes, good old Urea. Not by any other names with ‘Urea’ such as Imidazolidinyl Urea) will not react with Triethanolamine (to neutralising 0.5% Carbomer) creating nitrosamine or anything destructive?
Am I also correct to say that it is safe to use Urea of any concentration with the concentration of Triathanolamine required merely to neutralise 0.5% Carbomer?
By the way, could you tell me what exactly Carbomer is? I mean the actual chemical formula. You see, I have been using this site to help me calculate how much what to neutralise how much of another what. Provided that I know and can find the correct chemical formula, that is.
I want to see how much Sodium Bicarbonate is required to neutralise, say 0.5%, Carbomer.
The nearest I could find is Polyacrylic Acid, (C3H4O2)n.
Case 1: Sodium Bicarbonate + Carbomer
I went for only C3H4O2 instead of (C3H4O2)n.When I key in NaHCO3 + C3H4O2 =, there are a few results shown, very convenient for people like me who do not know what mix what equals to what.
I then chose NaC2H3O2 + CO2 + H2O as the product.One of the products is Sodium Acetate, NaC2H3O2. Is this correct?
I did not know Carbomer has Acetic Acid within because it does not have the slightest scent of that repugnant Acetic Acid!Case 2: Triethanolamine + Carbomer
Identical to Case 1, I went for only C3H4O2 instead of (C3H4O2)n.NaHCO3 + C6H15NO3 =
Nothing comes out; no hint. I think and think, it could be Triethanolamine Acetate.
a. NaHCO3 + C6H15NO3 = C8H19NO5 + CO2 + H2O
b. NaHCO3 + C6H15NO3 = C8H19NO5 + CO2
c. NaHCO3 + C6H15NO3 = C8H19NO5 + H2O
d. NaHCO3 + C6H15NO3 = C8H19NO5
All permutations result in nothing.
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you need a secondary amine group and a nitrosating agent to generate nitrosamines; TEA is a tertiary amine, not a secondary one, so it is not physically possible for it to form nitrosaminesalso, urea is not a nitrosating agent and cannot easily be turned into onecarbomer are a set of polymers of acrylic acid, which have variable chain lengths, complex structures, molecular weights of multiple million Daltons, and no general empirical formula; they are not the same thing as acrylic acid, so calculations made using acrylic acid are meaninglessas it happens, Lubrizol have made a handy chart showing how much base is required to neutralise their polymers (Figure 4 in this document); this is a good guide for carbomers in general
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Thank you very much @Bill_Toge for your assistance in calculation. You responded to my question on vapour pressure.
Thank you very much for this Carbomer-Urea-Nitrosating agent explanation.
I did a little homework as I did not know what secondary and tertiary amine groups are. I now see what they are!
http://www.chem.ucla.edu/~harding/IGOC/T/tertiary_amine.html
http://www.chem.ucla.edu/~harding/IGOC/S/secondary_amine.html
I got confused as to why TEA looks very different to the tertiary amine in the image.
TEA has CH2. In the image is CH3.
I then read the little note there “C = any carbon group except carbonyl”. Ah…that explains it.I notice that the label secondary and tertiary refers to the amount of carbon atoms. Secondary amine has two carbon, while tertiary amine has three carbon. I presume the more carbon atoms it has the more stable it is, hence it is the reason why TEA is not physically possible for it to form nitrosamines.
Nitrosating agents-Sodium Nitrate and Bronopol are the known and popular ones generating nitrosonium ions, also the reactivity of those ions is very high.
(Those combinations are still fuzzy to me as they are new to me)
Thank you very much for your detailed explanations.
I need to thank you because you put in that insane effort to respond/share your practical knowledge with us when I/we are not paying you! I have trouble sleeping soundly with too many unanswered questions.
I am not saying that others in this Chemist Corner community are not helping. The fact that this community even exists to helping each other, and most people here are not afraid of who is whose competitor is mind-blowing! I, however, notice that you are an extremely technical person. I happen to have deep curiosity mode switched on most of the time.
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no worries! if truth be told it’s no effort at all as far as I’m concerned; I’ve worked at the sharp end of the industry for 10 years now and accumulated most of my practical and theoretical knowledge by keeping my eyes and ears open, and I just offer advice etc. out of a desire to be helpfulthe reactivity of amines towards the nitrosonium ion can be summarised in this reaction diagram, which runs anti-clockwise from top left to top right:
with a primary amine (one carbon substituent, like the one in the diagram) the reaction goes to completion and forms a highly reactive diazonium saltwith a secondary amine (two carbon substituents) the reaction terminates at nitrosamine stage because there are no H atoms available to form the diazohydroxidewith tertiary amines (three carbon substituents) the reaction doesn’t occur, because the first intermediate is inherently unstable and there are no H atoms available to allow nitrosamine formation, so it decomposes back to the starting materialswith quaternary amines (four carbon substituents) the reaction doesn’t occur at all because there are no free coordination sites on the N -
I have just cracked the code to calculating how much an alkaliser is required to neutralise a given amount of Carbomer. The calculation is very easy! It is not as complicated as we thought it was! Acrylic Acid is the answer!
To make 1% Carbomer aqueous solution. Neutralised with Sodium Hydroxide-
1% Carbomer x 39.997 (MW of Sodium Hydroxide) / 72.063 (MW of Carbomer unit) x 0.7 = 0.389% of Sodium Hydroxide (70% neutralization)
Aligns with Lubrizol recommendation of 2.3% NaOH (18% active) to 1% Carbomer.
Calculated 2.3% of 18% NaOH is 0.414%.
To make 1% Carbomer aqueous solution. Neutralised with Triethanolamine-
1% Carbomer x 149.188 (MW of Triethanolamine) / 72.063 (MW of Carbomer unit) x 0.7 = 1.450% of Triethanolamine (70% neutralization)
Aligns with Lubrizol recommendation of 1.5% Triethanolamine (99% active) to 1% Carbomer.
On a different note, the European Commission Cosmetic ingredient database (CoSing) states that Triethanolamine of any kinds, its maximum concentration is 2.5% for leave-on products.
What if I want to use Triethanolamine to neutralise all acids including Carbomer, will the total content of Triethanolamine cause people to mutate into Super Villains?
My ‘new’ (partial) formulation is as follow:
0.725% TEA to neutralise 70% of Carbomer.
1.165% TEA to neutralise 100% Citric Acid (to make buffer).
1.141% TEA to neutralise 100% Glucono-delta Lactone (to make buffer).
Grand total of approximately 3.031% TEA.
As for the buffers, you may be wondering why 100% neutralisation. Just for the sake of calculation, looking at the worst-case scenario.
If all were 70% neutralised then the total TEA concentration is approximately 2.339%.
I know and understood from your explanation that Triethanolamine is something that we need not be frightened of. But is this ‘2.5% maximum’ a concern? Is it a valid concern? Another scaremonger?
Why Triethanolamine for all, you may ask. I was inspired as I was playing about with GdL and Sodium Lactate.
Sodium Lactate is hopeless. Only very little (~1%) of it and 0.5% Carbomer is liquefied.
0.5% Carbomer surprisingly survives with the presence of 3% Sodium Gluconate. Not gel. Water consistency. Yield value is still incredibly high. Cannot suspend ball bearing or big bubbles but small bubbles are suspended.This calculation could prove what is going on:
NaCl: MW 58.44 Sodium Lactate: MW 112.06 1% / MW 112.06 x MW58.44 = 0.52% (1% Sodium Lactate is same mol % of 0.52% NaCl. And then refer to Lubrizol NaCl sensitivity chart) The higher the molecular weight of a salt, the less Carbomer will be affected.
Acids and Triethanolamine appear to be best friends as they are mutually stuck together. Literally fully combined. The molecular weight of the salt is literally two molecules combined. Nothing is lost like how NaOH would split to H2O, and NaHCO3 split to CO2 and H2O.
If you wonder why do I need buffer…why all the convolution… It is because I have Urea in my formulation. To make matters worse, I fall back to using Carbomer, I have high temperature and high humidity issues, I have limited resources, I am not making things for profit, I am just a DIYer. All the ‘bad luck’ in a string. I gave up on Xanthan Gum and natural whatnot. I spent too much effort trying to “fix and make it better” to no avail. Gradually makes no sense.
I will take your words at face value if you said 3.031% or more TEA is not an issue. I can sleep soundly. I trust that you never provide me with factoids. You know some stuff about the EU regulations, I should be fine.
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I don’t understand that carbomer contributes the metal .
carbomer is used for water thickener. Why do we replace carbomer with xanthan gum? -
Typo metal instead of alkaline
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Cst4Ms4Tmps4 said:
On a different note, the European Commission Cosmetic ingredient database (CoSing) states that Triethanolamine of any kinds, its maximum concentration is 2.5% for leave-on products.
Interesting.
They even seem to restrict products where TEA has reacted with an acid
like TEA-carbomer or TEA-cocoate. -
I cannot get the gist of what you meant by the “metal” or “alkaline” part. What you are trying to say seems fragmented. Did you mean the neutralisation?
If it is about neutralisation then alkaline is used to neutralise Carbomer. Carbomer per se is acidic, it will not fully swell. It swells best at around pH 7.
Personally, I find Carbomer is the best suspending agent (and thickener because it gels).
The only time we want to use some other thickeners and suspending agents (usually “natural” ones such as Xanthan Gum) is when the formulation has electrolytes/salts, subject to heat (like the tropical heat where I live), low or high pH.Xanthan Gum is the best and the most natural thickener that I found. It has very high yield value, and is resistant to many things that Carbomer fails. This is assuming non-gel final product is not important because Xanthan Gum does not gel. I tried making it gel the way that I like but nothing make it gel as beautifully as Carbomer does. And assuming cloudiness does not matter (There are clear kind of Xanthan Gum. Mine is the regular cloudy kind).
The only drawback of Xanthan Gum is it can be tacky and slimy. I read somewhere in the Internet there are non-tacky and non-slimy types.
Oh yes! I did not see TEA-Carbomer, TEA-Acrylates, TEA-Salicylates! From A to Z!
Yeah. It appears that anything with TEA is dangerous. I think the reason is TEA is neither consumed in the neutralisation process, nor split into other un-dangerous components such as CO2 and H2O. TEA literally binds to acids as a whole.
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TEA doesn’t “bind” but simply form a salt. “Binding” would imply a chemical reaction which would lead to amid-bond formation as for example with cocamide MEA ode DEA. This is not possible with TEA because that one is a tertiary amine, the amid would be positively charged and hence highly reactive. TEA simply abstracts a proton from an acid such as carbomer. Because TEA is not a very strong base, its salts and especially salts with weaker acids such as carbomer, free and protonated TEA are in equilibrium with each other, they form a buffer. Although the equilibrium is usually on the salt side, more or less free TEA is present depending on pH.
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the legal limit is in place to limit the exposure to residual diethanolamine, which is produced during the manufacturing process and is typically present as an impurity, to the maximum dose known to be safemany of the limits in Annex III are based on the maximum dose which is known with absolute certainty to be safe - the practical limit could potentially be higher, but there is no positive and convincing proof
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You two “may be” correct!
Look what I have found!
https://personalcaretruth.com/2011/06/a-closer-look-at-triethanolamine-tea/
“In products intended for prolonged contact with the skin, the concentration of TEA should not exceed 5%.”
“TEA is lumped in with some other ingredients that have earned it the warning, “should not be used in products containing N-nitrosating agents to prevent the formation of nitrosamines.” However, because TEA is a tertiary amine, it does not react with nitrosating agents to produce nitrosamines. Using very sensitive analytical tools, a study by the Regulatory Toxicology and Pharmacology found when TEA was ingested with sodium nitrite, no significant nitrosamine formation was found.”
I do not know how reliable the site is, but I do see different “organisations” have different maximum usage rate of certain or all chemicals. And I agree that “testings” done on animals and humans are distorted. SLS for example, are tested by using patch, stuck on skin for 24 hours. Who the f**k in real-life leaves soap or detergent 24 hours on their skin! Water is poisonous and proven to have had killed people, it also strips lipids and water-soluble substances from skin making skin unnaturally dry, so why bother drinking and using it!
After looking at lots of stoichiometry, Triethanolamine simply can NOT be reduced. It can be reduced only with certain acids, such as Citric Acid releasing H2O, which is called “condensation reaction” (bloody fancy word that I learnt!). With Gluconic Acid, no H2O is released, hence no condensation reaction. No wonder the total molecular weight is massive, a combination of both Triethanolamine AND the said acid/s, compared to the same acid/s that are mixed with NaOh or NaHCO3!
Triethanolamine is not a conventional base that schools teach us, That is, must be some reaction (fizzes) to be valid. I never see fizzing mixing Triethanolamine with acids. Still waters run deep, perhaps…ummm.
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I admit, I kinda always think of TEA as triethylamine because that’s what I used in the lab and it shares the same abbreviation. Apart from the same behaviour of the central nitrogen, triethanolamine has also three primary alcohol groups which could form esters with for example fatty acids but these won’t as long as there’s an excess water present.Other types of chemical reactions (degradation) and even further condensation reactions are in theory possible but require harsh conditions. Sure, nature is seldom all or nothing, and hence such reactions happen at very faint quantities under mild conditions too. Danger arises if such faint quantities are not as faint as they should be or sufficient to pose a health risk.TEA is “free” to 99.9-whatever % and not bound to anything. What the rest does or degrades to… I don’t know how stable the molecule really is in a cosmetic mixture. That’s why I, personally, don’t trust TEA (both, actually). It’s more of a hunch than backed up science but my gut feeling was right more than once.
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Pharma said:I admit, I kinda always think of TEA as triethylamine because that’s what I used in the lab and it shares the same abbreviation.
trust me, it’s nowhere near as foul-smelling as triethylamine
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