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disodium EDTA
hello,
I am using 0.2% disodium EDTA in my formulations.
My question is: when is best to insert it?
I am doing creamy emulsions with mineral oil plus butters or other oils.
I added the EDTA into the water phase but it is not soluble at all. So, I wonder if its best to add it into the oil phase or in the cool down.
On the other hand if it is not soluble in water will it work properly, since its function is to quelate metals from the water?
I noticed as well that in the water phase (when I added EDTA) the pH drops very much, around 2….
Any thoughts?
Thank you ! -
10 Replies
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it goes into the water phase, but it takes a long time to dissolve at room temperature
also 0.05 - 0.1% is sufficient for the vast majority of products - 0.2% is a little excessive in my view
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I agree. 0.2% seems a bit much. I always add it near the beginning because it takes some time to dissolve.
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I also put it in the heated water phase at 0.1%, glad to read that’s ok.
The advice of Making Skincare however is 0.2%, so I understand it can be confusing. (below ‘Factors which greatly impact the effectiveness of your chosen preservative system’).
@Bill_Toge @Perry I do use 0.2% diNa EDTA in a toner with 2% salicylic acid, would that be too much also? (to prevent SA from binding with iron that is maybe present as contaminant) -
I also use 0.2% in shampoo systems and creams and never had issues with pH drop. It starts dissolving around 40 degrees Celsius. Check your supplier and the purity of your edta. I use also a buffer of citric/citrate in most of my products together with EDTA.
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@Doreen in practical terms 0.2% disodium EDTA is not ‘too much’, but for cold mixes it adds an awful lot of time to the process for very little added benefit; the reasons we add it are to increase the efficacy of the preservative system, and (for surfactant-based products) to ensure the products foams well if the consumer lives in a hard-water area, and it does both of these jobs very well at 0.1%
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@Bill_Toge
Ok, thanks for explaining!
Is it true that you need more, like 0.2% for SA not to bind with contaminants like iron, or would 0.1% be sufficient? My SA supplier gave me this advice and I don’t know it it’s accurate. -
the na2 edta is 4X more expensive here than the Na4 edta. Usage of 0.2% seems to be the most popular %
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One small detail to take into account as far as surfactants systems are concerned. At 0.2% or above surfactants might pass through the cell barrier of the stratum corneum especially in SLS and SLES systems. Use of betaine counters this effect
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As an alternative you can use 40% solution. It is more expensive, but you gain time.
@manstra can you elaborate why?.
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Or use Sodium Phytate
and do the environment a favor.
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