Manganese EDTA complex

The permeation and clearance of model ionic permeants after subconjunctival injection was assessed with NMR imaging. New Zealand white rabbit was the animal model and manganese ion (Mn ) and manganese EDTA complex (MnEDTA ) were the model permeants. The current study was divided into three parts in vitro, postmortem, and in vivo. Transscleral passive permeation experiments were conducted with excised sclera in side-by-side diffusion cells in vitro. Sub-conjunctival delivery experiments were conducted with rabbits postmortem and in vivo. The distribution and elimination of the probe permeants from the subconjunctival space after subconjunctival injections were determined by MRI. The permeability coefficients of Mn and MnEDTA across the sclera in vitro were 3.6 x 10 cm/s and 2.4 x 10 cm/s, respectively. 

Manganese(II) can be titrated directly to Mn(III) using hexacyanoferrate(III) as the oxidant. Alternatively, Mn(III), prepared by oxidation of the Mn(II)-EDTA complex with lead dioxide, can be determined by titration with standard iron(II) sulfate. 

Discussion. In mixtures of magnesium and manganese the sum of both ion concentrations may be determined by direct EDTA titration. Fluoride ion will demask magnesium selectively from its EDTA complex, and if excess of a standard solution of manganese ion is also added, the following reaction occurs at room temperature ... 

Mixtures of manganese, magnesium, and zinc can be similarly analysed. The first EDTA end point gives the sum of the three ions. Fluoride ion is added and the EDTA liberated from the magnesium-EDTA complex is titrated with manganese ion as detailed above. Following the second end point cyanide ion is added to displace zinc from its EDTA chelate and to form the stable cyanozincate complex [Zn(CN)4]2- the liberated EDTA (equivalent to the zinc) is titrated with standard manganese-ion solution. 

Manganese(II) is normally not readily autoxidized, but when it is complexed by, e.g., nitrilobis(methylenephosphonic acid) ready autoxidation by 02 occurs (Nowack and Stone 2000). Whether under such conditions OH are set free as in the autoxidation of EDTA-complexed Fe(II) (Yurkova et al. 1999), is not yet know. 

Mn zones showed the spread of the radioactivity from the cationic to the anionic values without any electrophoretic zone defined. In other words, at the intermediate EDTA concentrations, which were not high enough to complex all manganese present, both Mn-EDTA complexes and free Mn were present at each position of the electrophoretic rip moving in opposite directions and resulting in the spread of... 

Laurie SH, Tancok NP, McGrath SP et al. Influence of EDTA complexation on plant uptake of manganese (II). Plant Sci 1995 109 213-235. 

The stepwise unwrapping of edta from its manganese(III) complex by cyanide is reflected in a variable-order dependence on the incoming ligand. The kinetically observable steps follow initial rapid reaction to [Mn(CN)3(edta)] or [Mn(CN)4(edta)] . The cyanide dependence of the reverse reaction helped in the elucidation of the overall formation mechanism. " ... 

The effects of added ions on rates, arising from competitive formation of intermediate mixed complexes, have been described for acetate on the reaction of the edta complex of manganese(ii) with cobalt(ii), for acetate and phthalate on cobalt(ii)-nta plus nickel(ii), and for copper(ii) or excess lead(ii) on cadmium(ii)-cydta plus lead(n). ... 

Ethylene bis dithiocarbamic acid manganese zinc complex. See Mancozeb Ethylenebis (iminodiacetic acid) tetrasodium salt. See Tetrasodium EDTA Ethylene bis (mercaptoacetate). See Glycol dimercaptoacetate... 

A mixture of Mn, Mg, and Zn was analyzed as follows The 25.00-mL sample was treated with 0.25 g of NH30H Cr (hydroxylammonium chloride, a reducing agent that maintains manganese in the +2 state), 10 mL of ammonia buffer (pH 10), and a few drops of Calmagite indicator and then diluted to 100 mL. It was warmed to 40°C and titrated with 39.98 mL of 0.045 00 M EDTA to the blue end point. Then 2.5 g of NaF were added to displace Mg " from its EDTA complex. The liberated EDTA required 10.26 mL of standard 0.020 65 M Mn for complete titration. After this second end point was reached, 5 mL of 15 wt% aqueous KCN were added to displace Zn " from its EDTA complex. This time the liberated EDTA required 15.47 mL of standard 0.020 65 M Mn. Calculate the number of milligrams of each metal (Mn, Zn, and Mg " ) in the 25.00-mL sample of unknown. 

Zachara, J.M., P.L. Gassman, S.C. Smith, and D. Taylor. 1995a. Oxidation and adsorption of Co(n)EDTA complexes in subsurface materials with iron and manganese oxide grain coatings. Geochim. Cosmochim. Acta 59 4449-4464. 

Although the addition of manganese(u) to the reacting system in conditions of an excess of chromium(vi) over hydrazine causes a retardation of the rate of disappearance of the oxidant, the effect of the divalent cation is to provide a reaction pathway where one half of the hydrazine is oxidized to yield ammonia. A similar observation has been made on the reaction in excess reductant in the absence of Mn . In the presence of edta, however, where the chromium(vi) oxidation of the aminopolycarbo-xylate is very slow, the reaction rate increases— the product now being the substitution-inert Cr" -edta complex ion. Experimentally, half the chro-mium(vi) is converted to this product and this is considered to derive from a dimeric chromium(vi) species involving both edta and hydrazine as ligands. In the reaction with hydroxylamine, the stoicheiometry is dependent on the reagent in excess, i.e. in the presence of excess oxidant... 

After firing, the powder is washed in water typically with a small amount of complexing agent such as ethylenediarninetetraacetic acid (EDTA), sodium EDTA, or a weak acid such as citric acid to remove the excess chloride, volatile antimony oxychlorides which have recondensed on the phosphor during cooling, and manganese compounds which are not incorporated in the halophosphate lattice. The powder is then ready for suspension. 

By the use of masking agents, some of the cations in a mixture can often be masked so that they can no longer react with EDTA or with the indicator. An effective masking agent is the cyanide ion this forms stable cyanide complexes with the cations of Cd, Zn, Hg(II), Cu, Co, Ni, Ag, and the platinum metals, but not with the alkaline earths, manganese, and lead ... 

After dissolution of the alloy in a mixture of concentrated nitric and hydrochloric acids the iron is masked with triethanolamine in an alkaline medium, and the manganese titrated with standard EDTA solution using thymolphthalexone as indicator. The amount of iron(III) present must not exceed 25 mg per 100 mL of solution, otherwise the colour of the iron(III)-triethanolamine complex is so intense that the colour change of the indicator is obscured. Consequently, the procedure can only be used for samples of ferro-manganese containing more than about 40 per cent manganese. 

In the back-titration small amounts of copper and zinc and trace amounts of manganese are quantitatively displaced from the EDTA and are complexed by the triethanolamine small quantities of cobalt are converted into a triethanolamine complex during the titration. Relatively high concentrations of copper can be masked in the alkaline medium by the addition of thioglycollic acid until colourless. Manganese, if present in quantities of more than 1 mg, may be oxidised by air and forms a manganese(III)-triethanolamine complex, which is intensely green in colour this does not occur if a little hydroxylammonium chloride solution is added. 

The rate of peroxide decomposition and the resultant rate of oxidation are markedly increased by the presence of ions of metals such as iron, copper, manganese, and cobalt [13]. This catalytic decomposition is based on a redox mechanism, as in Figure 15.2. Consequently, it is important to control and limit the amounts of metal impurities in raw rubber. The influence of antioxidants against these rubber poisons depends at least partially on a complex formation (chelation) of the damaging ion. In favor of this theory is the fact that simple chelating agents that have no aging-protective activity, like ethylene diamine tetracetic acid (EDTA), act as copper protectors. 

Other methods reported for the determination of beryllium include UV-visible spectrophotometry [80,81,83], gas chromatography (GC) [82], flame atomic absorption spectrometry (AAS) [84-88] and graphite furnace (GF) AAS [89-96]. The ligand acetylacetone (acac) reacts with beryllium to form a beryllium-acac complex, and has been extensively used as an extracting reagent of beryllium. Indeed, the solvent extraction of beryllium as the acety-lacetonate complex in the presence of EDTA has been used as a pretreatment method prior to atomic absorption spectrometry [85-87]. Less than 1 p,g of beryllium can be separated from milligram levels of iron, aluminium, chromium, zinc, copper, manganese, silver, selenium, and uranium by this method. See also Sect. 5.74.9. 

In the literature there are only few studies on the water-exchange processes of the manganese(II) species in general (33,38- 1), and the only seven-coordinate Mn(II) complexes studied are [Mn(EDTA) (H20)] and its derivatives (38,39,42,43). Such studies are essential for understanding the mechanism of the manganese-containing SOD mimetics. The volume of activation for the water-exchange reaction... 

The alternative to encapsulation of free manganese (called ensomes ) is to complex the manganese(II) with a ligand embedded in the lipid bilayer ( mem-somes ). Ethylenediaminetetraacetic acid (EDTA)-dihydroxypropyldecylamine (EDTA-DDP, Fig. 2) was ligated to manganese(II) and inserted into the bilayer of liposomes [61]. The 30-nm diameter liposomes formed had an R, value at 20 MHz of 37.4 mM"1 s1. When injected into rats with implanted C5 epitheloid... 

Another class of Mn( III) complexes involves the polyaminocarboxylic acid ligands. The earliest study appeared in 1962 ( 44) and was followed shortly by studies of the cyclohexane analog of EDTA as well as other derivatives of EDTA (45). A recent paper discusses the reactivity of the manganese (III )-diaminocyclohexanetetraacetate complex with hydrogen peroxide (46). A mechanism is proposed which involves complexation by the peroxide anion followed by subsequent electron transfer to produce the Mn(II) complex and the H02 radical. The results are interesting and indicate the potential for selective catalysis by the higher oxidation state manganese complexes. 

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