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Mercury-EDTA chelate

The precipitate was filtered, washed, and redissolved in an organic solvent. An excess of the mercury(II)/EDTA chelate was added ... [Pg.484]

Precipitation and Compiex-Formation Reactions Coulometric titrations with EDTA are carried out by reduction of the ammine mercury(II) EDTA chelate at a mercury cathode ... [Pg.658]

The pH can affect stability of the complex (i.e., K ) by affecting not only the form of the EDTA but also that of the metal ion. For example, hydroxy species may form (M2+ -I- OH- MOH" "). That is, OH- competes for the metal ion just as H" " competes for the Y ". Figure 9.2 (prepared from a spreadsheet—see Problem 20) shows how Kf changes with pH for three metal-EDTA chelates with moderate (Ca) to strong (Hg) formation constants. The calcium chelate is obviously too weak to be titrated in acid solution K < 1), while the mercury chelate is strong enough... [Pg.302]

Prepare a spreadsheet for Figure 9.2, log Kj vs. pH for the EDTA chelates of calcium, lead, and mercury. This will require calculating for EDTA and the Kf values for the chelates of calcium, lead, and mercury. Calculate at 0.5 pH intervals. Compare your plot with Figure 9.2. [Pg.312]

The treatment of metal poisoning is to administer a compound that binds the metal ion more strongly than does the group in the active centre of the enzyme. These compounds are known as chelating agents. For lead, the compound ethyl-enediaminetetraacetic acid (EDTA) is used. For mercury, dimercaptopropanol (dimercaprol) is used. [Pg.47]

Lead can accumulate in the bones and other body tissues unless removed soon after ingestion. In some cases, treatment with chelating agents such as EDTA has been used to remove lead, mercury, or other heavy metals from the body. Discuss the advantages and disadvantages of such treatment. Include both thermodynamic and kinetic arguments in your answer. [Pg.636]

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. [Pg.3765]

Sanders et al. (1983) have also shown that the effects of Cu(II) on the growth of crab larvae and on their metallothionein with copper chelate buffer systems must be interpreted on the basis of free Cu ion activity. The data obtained reveal predictable relations between [Cu ] in seawater and processes at the cellular and organismic levels. Similarly, the uptake of metal ions by plants (e.g., of aluminum) is usually related to free metal-ion activity. Others have shown that the chelation of a variety of metals reduces the toxicity of metals to organisms for example, a reduction in the uptake of mercury by fish in the presence of EDTA and cysteine a reduction in copper and/or zinc toxicity to... [Pg.634]

The concentration of (EDTA) ", and thus the ability to complex metal ions, will depend upon the pH. A decrease in pH results in an increase in the deprotonation of EDTA and hence an increase in the concentration of the ED I A ion. The effect of this is that only metal ions with a very high affinity for EDTA will be able to form stable complexes. The stability constants for the EDTA and [diethylenetriaminepentaacetic acid] - (DTPA ) complexes with some important metal ions that are of particular interest for chelation therapy are listed in Table 7.3. It is important to note that the stability of the EDTA and DTPA complexes with toxic metals, such as lead, mercury, cadmium, or plutonium are quite similar to those with essential metals such as zinc, cobalt or copper however, the Ca complex is many orders of magnitude lower. This has important implications for chelation therapy. First, the mobilization and excretion of zinc and other essential metals are likely to be increased, along with that of the toxic metal during EDTA treatment and secondly, the chelation of the ionic calcium in the blood, that can cause tetany and even death, can be avoided by administering the chelator as the calcium salt. [Pg.86]

Stability constants for the complexation of Cd by edta (H L) to yield [Cd(HL)] and [CdL] have been determined, as well as data on the complexation of zinc with propylenediaminetetra-acetic acid, zinc and cadmium with trans-1,2-cyclohexanediaminetetra-acetic acid, ° and mercury with diamino derivatives of succinic and malonic acids. Substituted hydroxamic acids have also been used as chelates in the complexation of zinc and cadmium. ... [Pg.411]

The effect of the heavy metals on the photosynthetic activity also depends on which solution is used to dissolve the metal. The uptake of the metallic elements is related to the concentration of free metal ions. For example, the addition of chelating agent such as ethylenediaminetettaacetic acid (EDTA) reduces the metal ion availability. EDTA decreased the concentrations of the free aqueous ionic form of the metals. The influence of the EDTA complexation on mercury availability was also noticed. The concentrations of mercuric chloride leading to 10% inhibition of the activity (Cio) photosystems II sub-membrane fractions immobilized in PVA-SbQ was about 10 mg/L in the absence of EDTA (Fig. 2) and 20 ii L in the presence of the chelating agent. [Pg.171]

I. Pharmacology. Penicillamine is a derivative of penicillin that has no antimicrobial activity but effectively chelates some heavy metals such as lead, mercury, and copper. It has been used as adjunctive therapy after initial treatment with calcium EDTA (see p 440) or BAL (dimercaprol p 413), although its use has largely been replaced by the oral chelator sucdmer (DMSA, p 501) because of its poor safety profile. Penicillamine is well absorbed orally, and the penicillamine-metal complex is eliminated in the urine. No parenteral form is available. [Pg.484]

Heavy-metal poisoning is treated by administering chelating agents—substances that combine with the metal ions and hold them very tightly. One effective antidote is the chelating agent ethylenediaminetetraacetic add, or EDTA, which will chelate all heavy metals except mercury. [Pg.335]

Sulfur and several sulfides, highly insoluble precipitates with solubility products as low as 1.6 X 10 for mercuric sulfide, have been used to concentrate trace metals from water. Sulfur, produced from (NH4)aS and HNO3 ( 0), coprecipitated several metals including mercury. Iron(III) sulfide (also used in a commercial process SULFEX) removes several metals (61) and is better than hydroxide in the presence of EDTA and other chelating agents (62). Lead sulfide has been used to collect silver for aqueous solution (63), molybdenum sulfide to collect arsenic from 2 M hydrochloric acid solution (64), and copper sulfide to concentrate cobalt and zinc from seawater (65). [Pg.21]

Some of the most successful and widely used chelating reagents include dimethylglyoxime for the gravimetric determination of nickel 1,10-phe-nanthroline and its derivatives for the colorimetric determination of iron and copper dithizone for the separation and colorimetric determination of a number of metals but particularly lead, silver, zinc, cadmium, and mercury the dithiocarbamates such as diethylammonium diethyldithiocarbamate and ammonium pyrrolidinedithiocarbamate, used for colorimetry but more widely applied now as selective extractants and the most successful titrant, EDTA. [Pg.110]

These generalized approaches have been applied specifically to the NMR spectra of EDTA, DTPA, MIDA, and NTA and the metal chelates formed by these ligands. Included are the chelates of the ions of the alkali metals, the alkaline earths, zinc, mercury, lead, molybdenum, zirconium, and some of the platinum metals. For the four chelating agents studied the nitrogen atoms within the ligands are definitely protonated before the carboxylate... [Pg.385]

Jokstad A, Thomassen Y, Bye E, Clench-Aas J, Aaseth J (1992) Dental amalgam and mercury. Pharmacol Toxicol 70 308-313 Jones MM (1991) New developments in therapeutic chelating agents as antidotes for metal poisoning. CRC Crit Rev Toxicol 21 209-233 Jones SG, Basinger MA, Jones MM, Gibbs SG (1982) A comparison of diethyldi-thiocarbamate and EDTA as antidotes for acute cadmium intoxication. Res Commun Chem Pathol Pharmacol 38 271-278 Joyce DA (1989) o-Penicillamine pharmacokinetics and pharmacodynamics in man. Pharmacol Ther 42 405-427... [Pg.302]

Ethylenediaminetetraacetic acid (EDTA) is used to treat mercury and lead poisoning through chelation therapy. It... [Pg.332]


See other pages where Mercury-EDTA chelate is mentioned: [Pg.126]    [Pg.157]    [Pg.359]    [Pg.167]    [Pg.1327]    [Pg.1328]    [Pg.64]    [Pg.417]    [Pg.72]    [Pg.173]    [Pg.200]    [Pg.14]    [Pg.149]    [Pg.421]    [Pg.2014]    [Pg.358]    [Pg.363]    [Pg.182]    [Pg.74]    [Pg.1163]    [Pg.96]    [Pg.85]    [Pg.42]    [Pg.67]    [Pg.329]    [Pg.109]    [Pg.470]    [Pg.150]    [Pg.66]   
See also in sourсe #XX -- [ Pg.207 ]




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