Ethylenediaminetetraacetic acid EDTA,-metal chelates

Infrared spectra have been given for many ethylenediaminetetraacetic acid (EDTA)-metal chelates (Sawyer, 1960) along with a listing of the major absorption... 

The complexers maybe tartrate, ethylenediaminetetraacetic acid (EDTA), tetrakis(2-hydroxypropyl)ethylenediamine, nittilotriacetic acid (NTA), or some other strong chelate. Numerous proprietary stabilizers, eg, sulfur compounds, nitrogen heterocycles, and cyanides (qv) are used (2,44). These formulated baths differ ia deposition rate, ease of waste treatment, stabiHty, bath life, copper color and ductiHty, operating temperature, and component concentration. Most have been developed for specific processes all deposit nearly pure copper metal. 

It is common for acid extracting solutions to contain ligands, such as fluoride, that, when combined with metals, increase their solubility. Chelates such as ethylenediaminetetraacetic acid (EDTA), which combine with metals and either bring them into solution or keep them in solution, are also commonly used. 

One of the earlier observations concerning the activation process was that it was inhibited by iron chelators (9,27). Kennedy et al. (46) demtmstrated that the metal chelator ethylenediaminetetraacetic acid (EDTA) inlubits the activation process, even... 

As an alternative to acid washing, soils can also be flushed with chelating agents. Examples of effective chelating agents include ethylenediaminetetraacetic acid (EDTA) and nitrilotriacetic acid (NTA), both of which readily bind and solubilize metals. Using this approach, Peters Shem (1992) have recently reported on the removal of lead from a contaminated soil. In this study, 0.1M EDTA removed 60% of the lead in a soil containing 10 000 mg lead/kg. 

The first chelating resins that were found to be really suitable for application in the field of selective cation absorption were those based on the aminodiacetate functional group.380 The first commercial resin based on this functional group, Dowex Al, was shown381 to have an affinity for a range of metals which was similar to the order of dissociation constants of the metal complexes with ethylenediaminetetraacetic acid (EDTA), i.e. 

The method is normally performed as follows [32,39] an aqueous solution of suitable oxides or salts is mixed with an a-hydroxycarboxylic acid, such as citric acid, and EG is added to the solution. At heating, an esterification process runs in the system leading to the formation of a stable gel in which the metal ions remain fixed. In the modified Pechini process, ethylenediaminetetraacetic acid (EDTA) has been used to replace citric acid due to its stronger chelating power. 

Off-line dicarbamate solvent extraction and ICP-MS analysis [317] provided part-per-trillion detection limits Cd (0.2 ppt), Co (0.3 ppt), Cu (3 ppt), Fe (21 ppt), Ni (2 ppt), Pb (0.5 ppt), and Zn (2 ppt). Off-line matrix removal and preconcentration using cellulose-immobilized ethylenediaminetetraacetic acid (EDTA) have also been reported [318]. Transition metals and rare earth elements were preconcentrated and separated from the matrix using on-line ion chromatography with a NTA chelating resin [319]. Isotope-dilution-based concentration measurement has also been used after matrix separation with a Chelex ion-exchange resin [320]. The pH, flow rate, resin volume, elution volume, and time required for isotope equilibration were optimized. A controlled-pore glass immobilized iminodiacetate based automated on-line matrix separation system has also been described [321]. Recoveries for most metals were between 62% and 113%. 

Ethylenediaminetetraacetic acid (EDTA) is a chelating agent that binds certain metals, especially iron and copper, which are essential to the nutrition of certain microorganisms. In this manner, it is a strong booster or enhancer of the activity of preservatives especially the parabens. Alone, it has the ability to increase the permeability of the bacterial cell wall and can kill Pseudomonas aeruginosa and E. coli by this activity effective concentration is 0.05-0.10%. 

The presence of complexing ligands in the diet or drinking water may dangerously affect the bio-availability of a metal in the blood or tissues one example of this is the use of powerful chelators, such as the anions of nitrilotriacetic acid or ethylenediaminetetraacetic acid (EDTA) as substitutes for phosphate in washing powders. It has been calculated that in some parts of the world the concentration of EDTA in ground or river water may be as high as 100 imol dm . ... 

An alternative approach which allows the separation of an excess of alkali metal ions from other cations uses a chelating ion-exchange resin. This type of resin forms chelates with the metal ions. The most common of these is Chelex-100 . This resin contains iminodiacetic acid functional groups which behave in a similar way to ethylenediaminetetraacetic acid (EDTA). It has been found that Chelex-100 , in acetate buffer at pH 5-6, can retain Al, Bi, Cd, Co, Cu, Fe, Ni, Pb, Mn, Mo, Sc, Sn, Th, U, V, W, Zn and Y, plus various rare-earth metals, while at the same time it does not retain alkali metals (e.g. Li, Na, Rb and Cs), alkali-earth metals (Be, Ca, Mg, Sr and Ba) and anions (F-, Cl-, Br- and I-). 

The antioxidant synergists enhance the effect of antioxidants. Chelating agents like ethylenediaminetetraacetic acid (EDTA) are commonly added to parenterals. They may reduce oxidative damage by forming complexes with oxidative metal ion catalysts. Chelating agents are further discussed in Section 14.2.6. 

Ethylenediaminetetraacetic acid (EDTA) is a polycarboxylic acid chelator its sodium salt (edetate disodium, Na EDTA), and a number of closely related compounds chelate many divalent and triva-lent metals. The cation used to make a water-soluble salt of EDTA has an important role in the toxicity of the chelator. Na EDTA causes hypocalcemic tetany. However, edetate calcium disodium (CaNa EDTA) can be used for treatment of poisoning by metals that have higher affinity for the chelating agent than does Ca +. 

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