EDDHA
Ethylenediaminedi(o-hydroxyphenylaceticacid) ["aceticacid"], complexing agent(chelator).
Also EHPG (N,N'-ethylenebis-2-(o-hydroxyphenyl)glycine).
Due to the strong bonds between Fe(III) and phenolic OH functions, chelates of this type are much stronger than those with pure carboxyl chelators such as EDTA and are therefore stable even at higher pH values.
The phenol-Fe(III) bond gives the complex a red to violet colour.