Tetrasodium EDTA is the salt formed from neutralizing ethylenediamine tetraacetic acid with sodium hydroxide. It is a chelating agent and used to prevent metal ions from binding to other ingredients. This helps keep the product and ingredients stable.

Tetrasodium EDTA comes as a white solid and is soluble in water.

Water. It's the most common cosmetic ingredient of all. You'll usually see it at the top of ingredient lists, meaning that it makes up the largest part of the product.

So why is it so popular? Water most often acts as a solvent - this means that it helps dissolve other ingredients into the formulation.