Ethylenediaminetetra-acetic acid EDTA

Multidentate ligands contain more than two coordinating atoms per molecule, e.g. 1,2-diaminoethanetetra-acetic acid (ethylenediaminetetra-acetic acid, EDTA),f which has two donor nitrogen atoms and four donor oxygen atoms in the molecule, can be hexadentate. 

Ru(bipy)3 formed in this reaction is reduced by the sacrificial electron donor sodium ethylenediaminetetra-acetic acid, EDTA. Cat is the colloidal catalyst. With platinum, the quantum yield of hydrogenation was 9.9 x 10 . The yield for C H hydrogenation was much lower. However, it could substantially be improv l by using a Pt colloid which was covered by palladium This example demonstrates that complex colloidal metal catalysts may have specific actions. Bimetalic alloys of high specific area often can prepared by radiolytic reduction of metal ions 3.44) Reactions of oxidizing radicals with colloidal metals have been investigated less thoroughly. OH radicals react with colloidal platinum to form a thin oxide layer which increases the optical absorbance in the UV and protects the colloid from further radical attack. Complexed halide atoms, such as Cl , Br, and I, also react... 

High-performance liquid chromatography (HPLC) with a micellar mobile phase or with a selective pre-column or reaction detection system has also been used to determine alkylenebis(dithiocarbamaes). ° Zineb and mancozeb residues in feed were determined by ion-pair HPLC with ultraviolet (UV) detection at 272 nm. These compounds were converted to water-soluble sodium salts with ethylenediaminetetra-acetic acid (EDTA) and sodium hydroxide. The extracts were ion-pair methylated with tetrabuthylammonium hydrogensulfate (ion-pair reagent) in a chloroform-hexane solvent mixture at pH 6.5-8.S. The use of an electrochemical detector has also been reported. ... 

The standard procedure for removal of active-site vanadium(V) has been to incubate V-BrPO in 0.1 Mphosphate-citrate buffer pH 3.8, containing 10 mM ethylenediaminetetra-acetic acid (edta). These conditions remove over 95% of the vanadium, which produces the inactive apo-BrPO derivative [1,45]. The essential component of the apoprotein preparation is the phosphate, without which vanadium is not completely removed and the enzyme is not completely inactivated [46], In fact phosphate in the absence of edta is sufficient for preparation of apo-BrPO [46] inactivation by phosphate is much faster at low pH (pH 4) than at neutral or higher pH. However, phosphate inactivation does not occur in the presence of dihydrogen peroxide [46],... 

Alkylphosphonate groups are monodentate donors of intermediate hardness that may replace carboxylate groups in chelating agents such as nitrilotriacetic acid (NTA), ethylenediaminetetra-acetic acid (EDTA), and diethylenetriaminepentaacetic acid (DTPA). The corresponding ligands nitrilotrimethylenephosphonic acid (NTP), 1, ethylenediaminetetramethylenephosphonic acid (EDTP),... 

Multidentate Ugand - these have several points of attachment, e.g. ethylenediaminetetra-acetic acid (EDTA), which is a hexadentate ligand (six points of attachment) (Fig. 23.2). 

The proteins of the cell envelope of Ps. aeruginosa have received somewhat less attention than the other components. Recently, it was found [17] that the envelope contains a wide variety of proteins. There do, however, appear to be three characteristic proteins, two of which are gylcoproteins and are found associated with the protein-lipopolysaccharide complex released on treatment of envelopes with ethylenediaminetetra-acetic acid (EDTA). This complex is part of the outer layer of the envelope [18]. 

The complexing ability of ethylenediaminetetra-acetic acid (EDTA, H4Y) has been exploited in the coulometric titration of metal ions. The method depends on the reduction of the mercury(II) or cadmium chelate of EDTA and on the titration of the metal ion (for example, magnesium) to be determined by the anion of EDTA that is released. 

Soon after the introduction of propofol in 1989, clusters of infections related to its use were reported, and there have since been several reports (77,78). The complications include hypotension, tachycardia, septic shock, convulsions, and death. Ethylenediaminetetra-acetic acid (EDTA) was added to the formulation to retard microbial growth. However, there have been concerns over the effects of this additive on trace element homeostasis, particularly when it is used in intensive care units for long-term sedation. Five randomized controlled trials have been reviewed, and minimal or no effects have been found on zinc, magnesium, or calcium homeostasis. However, there is no evidence to suggest that cluster infection has been or will be reduced with this formulation and there is still a need for care with sterility when using this product. 

Improvements in modes of complexing by Marsh (1950), who separated lanthanides by fractional crystallisation of the ethylenediaminetetra-acetic acid (EDTA) complexes, have been coupled with the ion exchange technique by Vickery (1952). EDTA proved an even more satisfactory complexing agent than citric acid and gave purer specimens than any other method. 

This reaction is particularly catalyzed by copper. A large excess of ammonia and the addition of complexing agents such as ethylenediaminetetra-acetic acid (EDTA) are used as countermeasures. 

Trypsin ethylenediaminetetra-acetic acid (EDTA) (Gibco-BRL Life Technologies, Gaithersburg, MD). 

Fig. 2 Chelation between a metal ion (M+) and ethylenediaminetetra-acetic acid (EDTA), a well-known laboratory ligand. Note that the six coordination bonds (white) are made between dissociated -0 groups and lone pairs of electrons (denoted by double dots) on the N atoms of the EDTA. Similar coordination bonds are made in fulvic acid chelates.

The linkage of chemical processes in thermodynamic cycles arising from the definition of the state functions (the state of a system is independent on the way on which it was reached) is a great virtue that can immediately be exploited by calorimetry. In this sense, making use of the protonation properties is just a special case in the much broader field of competition analysis [25]. In fact, any molecular species that is expelled or taken up by the host as a result of binding, the guest of interest may serve as a probe in calorimetric determinations. Prominent examples include the binding or release of metal cations from proteins (e.g. Ca +, Mg +) which can be linked to their complexation by complexones (ethylenediaminetetra-acetic acid (EDTA) or similar). 

The reaction is terminated by the addition of ethylenediaminetetra-acetic acid (EDTA) to a final concentration of 25 mM. 

Gardiner, J., 1976. Complexation of trace metals by ethylenediaminetetra acetic acid (EDTA) in natural waters. Water. Res., 10 507—514. 

Complex formation is used extensively in water analysis. The determination of hardness, Ca and Mg concentration, employs the com-plexation of these metals with the chelating agent ethylenediaminetetra-acetic acid (EDTA) the titrimetric finish of the chemical oxygen demand (COD) test uses the complexing agent 1,10-phenanthroline to detect the presence of Fe and so indicate the endpoint chloride analysis by. the mercurimetric method depends on the formation of the complex HgCl taq) between Hg " and the chloride ion. 

In the laboratory, chelating agents have been used to overcome resistance in bacteria. For example, ethylenediaminetetra-acetic acid (EDTA) restored susceptibility in polymyxin-resistant strains of Pseudomonas, presumably by removing calcium and magnesium from the plasma membrane (Brown and Richards, 1965). EDTA also restored susceptibility to hospital-isolated strains of penicillin-resistant Staphylococcus aureus (Rawal, 1969). Further, oxytetra-... 

In experimental work, the need often arises to maintain a predetermined concentration of a given metal ion, a concentration that is not allowed to rise above this level nor fall below it. This situation is met by the use of metal ion buffers which maintain a steady pM just as hydrogen ion buffers maintain a steady pH. With their help, free metal ions are replenished (as they are removed by the reaction) from a reservoir of bound metal complex. The first complexing agents to be used for this purpose were citrate and tartrate ions, but much more application has been found for ethylenediaminetetra-acetic acid (EDTA) (cf. 11.27), diethylenetriaminepenta-acetic acid (DTPA), and nitrilotriacetic acid (NTA). The necessary calculations will be found in Perrin and Dempsey (1974). 

Chelating agents also are effective in certain cases. Ethylenediaminetetra-acetic acid (EDTA) forms strong chelates with alkaline earth elements and can be used to protect magnesium and calcium from reaction with phosphate, sulfate, selenium, boron, aluminum, and silicon. 8-Hydroxyquinoline has been used to protect magnesium and calcium from aluminum. 

The removal of calcium carbonate, calcium phosphate, and other mineral salts found in shell waste is accomplished by extraction with dilute acids. It has been shown to be important that the amount of acid is stoichiometrically equal to or greater than all the minerals present in the shell to ensure complete DM (Sahidi and Synowiecki 1991). Hydrochloric acid at room temperature and a reaction time of 2-3 h was most commonly used even though DA and chain hydrolysis may be observed (No and Meyers 1995). In order to minimize modifications of the native chitins, the use of ethylenediaminetetra acetic acid (EDTA) for DM or combined DP and DM has been suggested (Foster and Hackman 1957, Austin et al. 1981). 

Aminopolycarboxylic acids (ethylenediaminetetra-acetic acid (EDTA), 1,2-diaminocyclohexanetetra-acetic acid, bis-(aminoethyl)glycolether-N,N,N, N -tetraaceticacid, diethylenetriaminepentaacetic acid and nitroacetic acid) can be quantified through their inhibitory effects on metal-catalyzed reactions, whether by kinetic methods (at concentrations between 10 and 10 mol 1 or by direct catalytic titration... 

The concentration of copper(II) is a solution can be determined by titrating with ethylenediaminetetra-acetic acid (EDTA). At a wavelength of 745 nm, the copper-EDTA complex has a much higher molar absorption coefficient than Cu(II), which means that a plot similar to Figure 1C would be obtained. 

Pertinent to this point is the study of the effect of typical ligands on the rate of oxidation " The results with ethylenediaminetetra-acetic acid (EDTA), ethylenediamine (EN) and CN are reported in Table 20. 

---