Preparation of hydrogels based on polyaspartic acid, in a variety of physical forms ranging from fiber to particle, can potentially enable facile separation of the chelated ions from a solution. Therefore, despite being weaker than EDTA, polyaspartic acid can still be regarded as a viable alternative due to these features as well as biocompatibility, and biodegradability. S,S-Ethylenediamine-N,N′-disuccinic acid (EDDS)
A structural isomer of EDTA, ethylenediamine-N,N′-disuccinic acid (EDDS) is readily biodegradable at high rate in its S,S form. Methylglycinediacetic acid (MGDA)
Trisodium dicarboxymethyl alaninate, also known as methylglycinediacetic acid (MGDA), has a high rate of biodegradation at over 68%, but unlike many other chelating agents can degrade without the assistance of adapted bacteria. Additionally, unlike EDDS or IDS, MGDA can withstand higher temperatures while maintaining a high stability as well as the entire pH range. MGDA has been shown to be an effective chelating agent, with a capacity for mobilization comparable with that of nitrilotriacetic acid (NTA), with application to water for industrial use and for the removal of calcium oxalate from urine from patients with kidney stones. Methods of detection and analysis
The most sensitive method of detecting and measuring EDTA in biological samples is selected reaction monitoring capillary electrophoresis mass spectrometry (SRM-CE/MS), which has a detection limit of 7.3 ng/mL in human plasma and a quantitation limit of 15 ng/mL. This method works with sample volumes as small as 7–8 nL.EDTA has also been measured in non-alcoholic beverages using high performance liquid chromatography (HPLC) at a level of 2.0 μg/mL.
EDTA4− usually binds to a metal cation through its two amines and four carboxylates, i.e., it is It a hexadentate ("six-toothed") chelating agent. Many of the resulting coordination compounds adopt octahedral geometry. Although of little consequence for its applications, these octahedral complexes are chiral. The cobalt(III) anion [Co(EDTA)]− has been resolved into enantiomers. Many complexes of EDTA4− adopt more complex structures due to either the formation of an additional bond to water, i.e. seven-coordinate complexes, or the displacement of one carboxylate arm by water. The iron(III) complex of EDTA is seven-coordinate. Early work on the development of EDTA was undertaken by Gerold Schwarzenbach in the 1940s. EDTA forms especially strong complexes with Mn(II), Cu(II), Fe(III), Pb(II) and Co(III).Several features of EDTAs complexes are relevant to its applications. First, because of its high denticity, this ligand has a high affinity for metal cations:

[Fe(H2O)6]3+  +  H4EDTA  ⇌ [Fe(EDTA)]−  +  6 H2O  +  4 H+   Keq = 1025.1Written in this way, the equilibrium quotient shows that metal ions compete with protons for binding to EDTA. Because metal ions are extensively enveloped by EDTA, their catalytic properties are often suppressed. Finally, since complexes of EDTA4− are anionic, they tend to be highly soluble in water. For this reason, EDTA is able to dissolve deposits of metal oxides and carbonates. The pKa values of free EDTA are 0, 1.5, 2, 2.66 (deprotonation of the four carboxyl groups) and 6.16, 10.24 (deprotonation of the two amino groups).