EDTA

Ethylenediaminetetraacetic acid (EDTA), also known by several other names, is a chemical used for both industrial and medical purposes.

It is an aminopolycarboxylic acid and a colourless, water-soluble solid. Its conjugate base is ethylenediaminetetraacetate. It is widely used to dissolve limescale. Its usefulness arises because of its role as a hexadentate (“six-toothed”) ligand and chelating agent.