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Zhao H, Meng B, Sun G, Lin CJ, Feng X, Sommar J. Chemistry and Isotope Fractionation of Divalent Mercury during Aqueous Reduction Mediated by Selected Oxygenated Organic Ligands. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:13376-13386. [PMID: 34520177 DOI: 10.1021/acs.est.1c03171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We have investigated the chemistry and Hg isotope fractionation during the aqueous reduction of HgII by oxalic acid, p-quinone, quinol, and anthraquinone-2,6-disulfonate (AQDS), a derivate of anthraquinone (AQ) that is found in secondary organic aerosols (SOA) and building blocks of natural organic matter (NOM). Each reaction was examined for the effects of light, pH, and dissolved O2. Using an excess of ligand, UVB photolysis of HgII was seen to follow pseudo-first-order kinetics, with the highest rate of ∼10-3 s-1 observed for AQDS and oxalic acid. Mass-dependent fractionation (MDF) occurs by the normal kinetic isotope effect (KIE). Only the oxalate ion, rather than oxalic acid, is photoreactive when present in HgC2O4, which decomposes via two separate pathways distinguishable by isotope anomalies. Upon UVB photolysis, only the reduction mediated by AQDS results in a large odd number mass-independent fractionation (odd-MIF) signified by enrichment of odd isotopes in the reactant. Consistent with the rate, MDF, and odd-MIF reported for fulvic acid, our AQDS result confirms previous assumptions that quinones control HgII reduction in NOM-rich waters. Given the magnitude of odd-MIF triggered via a radical pair mechanism and the significant rate in the presence of air, reduction of HgII by photoproducts of AQDS may help explain the positive odd-MIF observed in ambient aerosols depleted of HgII.
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Affiliation(s)
- Huifang Zhao
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
- School of Geography & Environmental Science, Guizhou Normal University, Guiyang 550025, China
| | - Bo Meng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Guangyi Sun
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Che-Jen Lin
- Center for Advances in Water and Air Quality, Lamar University, Beaumont, Texas 77710, United States
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
- Center for Excellence in Quaternary Science and Global Change, Chinese Academy of Sciences, Xian 710061, China
| | - Jonas Sommar
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
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Szekeres LI, Bálint S, Galbács G, Kálomista I, Kiss T, Larsen FH, Hemmingsen L, Jancsó A. Hg 2+ and Cd 2+ binding of a bioinspired hexapeptide with two cysteine units constructed as a minimalistic metal ion sensing fluorescent probe. Dalton Trans 2019; 48:8327-8339. [PMID: 31111849 DOI: 10.1039/c9dt01141b] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Hg2+ and Cd2+ complexation of a short hexapeptide, Ac-DCSSCY-NH2 (DY), was studied by pH-potentiometry, UV and NMR spectroscopy and fluorimetry in aqueous solutions and the Hg2+-binding ability of the ligand was also described in an immobilized form, where the peptides were anchored to a hydrophilic resin. Hg2+ was demonstrated to form a 1 : 1 complex with the ligand even at pH = 2.0 while Cd2+ coordination by the peptide takes place only above pH ∼ 3.5. Both metal ions form bis-ligand complexes by the coordination of four Cys-thiolates at ligand excess above pH ∼ 5.5 (Cd2+) and 7.0 (Hg2+). Fluorescence studies demonstrated a Hg2+ induced concentration-dependent quenching of the Tyr fluorescence until a 1 : 1 Hg2+ : DY ratio. The fluorescence emission intensity decreases linearly with the increasing Hg2+ concentration in a range of over two orders of magnitude. The fact that this occurs even in the presence of 1.0 eq. of Cd2+ per ligand reflects a complete displacement of the latter metal ion by Hg2+ from its peptide-bound form. The immobilized peptide was also shown to bind Hg2+ very efficiently even from samples at pH = 2.0. However, the existence of lower affinity binding sites was also demonstrated by binding of more than 1.0 eq. of Hg2+ per immobilized DY molecule under Hg2+-excess conditions. Experiments performed with a mixture of four metal ions, Hg2+, Cd2+, Zn2+ and Ni2+, indicate that this molecular probe may potentially be used in Hg2+-sensing systems under acidic conditions for the measurement of μM range concentrations.
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Affiliation(s)
- Levente I Szekeres
- Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, Szeged, H-6720, Hungary.
| | - Sára Bálint
- Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, Szeged, H-6720, Hungary.
| | - Gábor Galbács
- Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, Szeged, H-6720, Hungary.
| | - Ildikó Kálomista
- Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, Szeged, H-6720, Hungary.
| | - Tamás Kiss
- Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, Szeged, H-6720, Hungary.
| | - Flemming H Larsen
- Department of Food Science, University of Copenhagen, Rolighedsvej 30, 1958 Frederiksberg C, Denmark
| | - Lars Hemmingsen
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Attila Jancsó
- Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, Szeged, H-6720, Hungary.
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Gharib F, Zare K, Majlesi K. Ionic Strength Dependence of Formation Constants, Protonation and Complexation of Phenylalanine with Dioxovanadium(V) at different temperatures. JOURNAL OF CHEMICAL RESEARCH 2019. [DOI: 10.3184/030823400103166896] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The protonation constants of phenylalanine and the stability constants of the complexes between dioxovanadium(V) ion and phenylalanine have been determined spectrophotometrically, in the temperature range 15–35°C and ionic strength ranging from 0.1 to 1.5 mol dm−3 sodium perchlorate as a background salt, in the pH range 1.5–10.5, with high ligand to metal ratios. The values of enthalpy and entropy changes based on these formation constants were calculated. The dependence of protonation and the stability constants on ionic strength are described by a Debye-Huckel type equation.
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Affiliation(s)
- Farrokh Gharib
- Chemistry Department, Shahid Beheshti University, Tehran, Evin, Iran
| | - Karim Zare
- Chemistry Department, Shahid Beheshti University, Tehran, Evin, Iran
| | - Kavosh Majlesi
- Chemistry Department, Islamic Azad University, Science and Research Branch, Tehran, Hesarak, Iran
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Tinkov AA, Ajsuvakova OP, Skalnaya MG, Popova EV, Sinitskii AI, Nemereshina ON, Gatiatulina ER, Nikonorov AA, Skalny AV. Mercury and metabolic syndrome: a review of experimental and clinical observations. Biometals 2015; 28:231-54. [DOI: 10.1007/s10534-015-9823-2] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 01/15/2015] [Indexed: 12/16/2022]
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Zhang L, Yuan Y, Wen X, Li Y, Cao C, Xiong Q. A coordination and ligand replacement based three-input colorimetric logic gate sensing platform for melamine, mercury ions, and cysteine. RSC Adv 2015. [DOI: 10.1039/c5ra09570k] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A three-input colorimetric logic gate of melamine, cysteine, and Hg2+using Au NP has been reported, in which the colour changes of the Au NPs solution provide sensitive and selective detections of melamine, cysteine, and Hg2+.
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Affiliation(s)
- Lulu Zhang
- Division of Physics and Applied Physics
- School of Physical and Mathematical Sciences
- Nanyang Technological University
- Singapore 637371
| | - Yanwen Yuan
- Division of Physics and Applied Physics
- School of Physical and Mathematical Sciences
- Nanyang Technological University
- Singapore 637371
| | - Xinglin Wen
- Division of Physics and Applied Physics
- School of Physical and Mathematical Sciences
- Nanyang Technological University
- Singapore 637371
| | - Yue Li
- Key Laboratory of Materials Physics
- Institute of Solid State Physics
- Chinese Academy of Sciences
- Hefei
- P. R. China
| | - Cuong Cao
- Institute for Global Food Security
- School of Biological Sciences
- Queen’s University Belfast
- Belfast
- UK
| | - Qihua Xiong
- Division of Physics and Applied Physics
- School of Physical and Mathematical Sciences
- Nanyang Technological University
- Singapore 637371
- NOVITAS
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Lin H, Morrell-Falvey JL, Rao B, Liang L, Gu B. Coupled mercury-cell sorption, reduction, and oxidation on methylmercury production by Geobacter sulfurreducens PCA. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:11969-76. [PMID: 25268220 DOI: 10.1021/es502537a] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
G. sulfurreducens PCA cells have been shown to reduce, sorb, and methylate Hg(II) species, but it is unclear whether this organism can oxidize and methylate dissolved elemental Hg(0) as shown for Desulfovibrio desulfuricans ND132. Using Hg(II) and Hg(0) separately as Hg sources in washed cell assays in phosphate buffered saline (pH 7.4), we report how cell-mediated Hg reduction and oxidation compete or synergize with sorption, thus affecting the production of toxic methylmercury by PCA cells. Methylation is found to be positively correlated to Hg sorption (r = 0.73) but negatively correlated to Hg reduction (r = -0.62). These reactions depend on the Hg and cell concentrations or the ratio of Hg to cellular thiols (-SH). Oxidation and methylation of Hg(0) are favored at relatively low Hg to cell-SH molar ratios (e.g., <1). Increasing Hg to cell ratios from 0.25 × 10(-19) to 25 × 10(-19) moles-Hg/cell (equivalent to Hg/cell-SH of 0.71 to 71) shifts the major reaction from oxidation to reduction. In the absence of five outer membrane c-type cytochromes, mutant ΔomcBESTZ also shows decreases in Hg reduction and increases in methylation. However, the presence of competing thiol-binding ions such as Zn(2+) leads to increased Hg reduction and decreased methylation. These results suggest that the coupled cell-Hg sorption and redox transformations are important in controlling the rates of Hg uptake and methylation by G. sulfurreducens PCA in anoxic environments.
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Affiliation(s)
- Hui Lin
- Environmental Sciences Division and ‡Biosciences Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
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Wang X, Qu R, Wei Z, Yang X, Wang Z. Effect of water quality on mercury toxicity to Photobacterium phosphoreum: Model development and its application in natural waters. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2014; 104:231-238. [PMID: 24726934 DOI: 10.1016/j.ecoenv.2014.03.029] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Revised: 03/23/2014] [Accepted: 03/24/2014] [Indexed: 06/03/2023]
Abstract
Mercury (Hg) compounds are widely distributed toxic environmental and industrial pollutants and they may bring danger to growth and development of aquatic organisms. The distribution of Hg species in the 3 percent NaCl solution was calculated using the chemical equilibrium model Visual MINTEQ, which demonstrated that Hg was mainly complexed by chlorides in the pH range 5.0-9.0 and the proportions of HgCl4(2-), HgCl3(-) and HgCl2(aq) reached to 95 percent of total Hg. Then the effects of cations (Ca(2+), Mg(2+), K(+) and H(+)), anions (HCO3(-), NO3(-), SO4(2-) and HPO4(2-)) and complexing agents (ethylene diamine tetraacetic acid (EDTA) and dissolved organic matter (DOM)) on Hg toxicity to Photobacterium phosphoreum were evaluated in standardized 15min acute toxicity tests. The significant increase of 6.3-fold in EC50 data with increasing pH was observed over the tested pH range of 5.0-8.0, which suggested the possible competition between hydroxyl and the negatively charged chloro-complex. By contrast, it was found that major cations (Ca(2+), Mg(2+) and K(+)) have little effect on Hg toxicity to P. phosphoreum. An interesting finding was that the addition of HPO4(2-) significantly increased Hg toxicity, which may imply that the addition of phosphate increased the soluble Hg-chloro complex species. Additions of complexing agents (EDTA and DOM) into the exposure water increased Hg bioavailability via complexation of Hg. Finally, a model which incorporated the effect of pH, HPO4(2-), HCO3(-), SO4(2-) and DOM on Hg toxicity was developed to predict acute Hg toxicity for P. phosphoreum, which may be a useful tool in setting realistic water quality criteria for different types of water.
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Affiliation(s)
- Xinghao Wang
- State Key Laboratory of Pollution Control and Resources Reuse, School of Environment, Nanjing University, Nanjing 210026, Jiangsu, PR China
| | - Ruijuan Qu
- State Key Laboratory of Pollution Control and Resources Reuse, School of Environment, Nanjing University, Nanjing 210026, Jiangsu, PR China
| | - Zhongbo Wei
- State Key Laboratory of Pollution Control and Resources Reuse, School of Environment, Nanjing University, Nanjing 210026, Jiangsu, PR China
| | - Xi Yang
- State Key Laboratory of Pollution Control and Resources Reuse, School of Environment, Nanjing University, Nanjing 210026, Jiangsu, PR China
| | - Zunyao Wang
- State Key Laboratory of Pollution Control and Resources Reuse, School of Environment, Nanjing University, Nanjing 210026, Jiangsu, PR China.
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Properties of dihydroasparagusic acid and its use as an antidote against mercury(II) poisoning. MONATSHEFTE FUR CHEMIE 2013. [DOI: 10.1007/s00706-013-1095-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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9
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Kochergina LA, Lytkin AI, Krutova ON. Influence of temperature on the heats of acid-base reactions in L-glutamine aqueous solution. RUSS J INORG CHEM+ 2013. [DOI: 10.1134/s0036023613060144] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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10
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Ryzhakov AM, Gruzdev MS, Pyreu DF, Kozlovskii EV, Kumeev RS. Thermodynamics of mixed-ligand complexation of mercury(II) ethylenediaminetetraacetate with histidine and lysine in aqueous solution. RUSS J COORD CHEM+ 2010. [DOI: 10.1134/s1070328410080026] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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11
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Kornev VI, Kardapol’tsev AA. Heteroligand mercury(II) complexes with aspartic, tartaric, and citric acids. RUSS J COORD CHEM+ 2008. [DOI: 10.1134/s107032840812004x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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12
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Vadi M, Zare Z, Nasiri K. Ionic strength dependence of formation constants, protonation, and complexation of aspartic acid with dioxovanadium (V). RUSS J INORG CHEM+ 2007. [DOI: 10.1134/s0036023607050294] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
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13
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Wright JG, Natan MJ, MacDonnel FM, Ralston DM, O'Halloran TV. Mercury(II)-Thiolate Chemistry and the Mechanism of the Heavy Metal Biosensor MerR. PROGRESS IN INORGANIC CHEMISTRY 2007. [DOI: 10.1002/9780470166390.ch6] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Majlesi K, Zare K. A modified equation for the calculation of the stability constants of W(VI)–NTA, Mo(VI)–NTA and Mo(VI)–glutamic acid complexes at different ionic strengths. J Mol Liq 2006. [DOI: 10.1016/j.molliq.2005.11.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Gharib, F, Shamel, A, Lotfi, F. Ionic Strength Dependence of Formation Constants, Complexation of Glycine with Dioxouranium(VI) Ion. REV INORG CHEM 2005. [DOI: 10.1515/revic.2005.25.4.361] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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16
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Gharib, F, Zare, K, Kia, M. Dioxovanadium(V) Complexes of Some Sulphur-Containing Ligands. REV INORG CHEM 2005. [DOI: 10.1515/revic.2005.25.1.67] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Gharib, F, Malekani, M. Ionic Strength Dependence of Formation Constants: Complexation of Histidine with Molybdenum (VI). REV INORG CHEM 2003. [DOI: 10.1515/revic.2003.23.1.97] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
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Monajjemi M, Gharib F, Aghaei H, Shafiee G, Taghvamanesh A, Shamel A. Thallium(I) Complexes of Some Sulphur-Containing Ligands. MAIN GROUP METAL CHEMISTRY 2003. [DOI: 10.1515/mgmc.2003.26.1.39] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
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Stypinski-Mis B, Anderegg G. The stability of palladium(II) complexes with sulphur-containing ligands. Anal Chim Acta 2000. [DOI: 10.1016/s0003-2670(99)00776-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Köszegi-Szalai H, Paál T, Barcza L. Comparative Studies on the Complex-Formation Equilibria of Mercury(II) with Acetylcysteine and Captopril. ACTA ACUST UNITED AC 2000. [DOI: 10.1524/zpch.2000.214.1.045] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The complex-formation equilibria of mercury(II) with acetylcysteine and captopril have been studied by pH-metric and liquid-liquid extraction methods applying dithizone as a competitive ligand during the latter measurements. The stability constants of three differently protonated Hg(II)/ligand 1:2 complexes of extreme stability have been determined by the combination of extraction and pH-metric data.The formation of the less stabil Hg(II)-ligand 1:3 complexes with the coordination of three sulfhydrilate groups has been followed and the values of βThe differences in the Hg(II) complex formation and protonation equilibria between the two ligands and the possible binding sites in the complexes have been discussed.
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Çakır S, Biçer E, Çakır O. Electrochemical study of cystine in the presence of cadmium and folic acid1In honour of Professor Petr Zuman’s visit to our University.1. J Inorg Biochem 1999. [DOI: 10.1016/s0162-0134(99)00207-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Heyrovský M, Mader P, Veselá V, Fedurco M. The reactions of cystine at mercury electrodes. J Electroanal Chem (Lausanne) 1994. [DOI: 10.1016/0022-0728(94)87082-9] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Abstract
The proton NMR spectrum of glycine was monitored in D2O solution as a function of added Hg(II) concentration and pD. Reliable values were established for formation constants for the Hg(II):glycine 1:1 and 1:2 complexes and also for the mixed glycine/deuteroxy and glycine/chloride complexes. Ligand exchange kinetics are relatively slow, and it is possible to observe coupling to 199Hg through the coordinating nitrogen. The formation constants were used to calculate speciation over a range of ligand concentrations for the Hg(II)/glycine and Hg(II)/glycine/chloride systems.
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Affiliation(s)
- R S Reid
- Department of Chemistry, University of Saskatchewan, Saskatoon, Canada
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26
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Solvent extraction studies of Hg(II) and Zn(II) with dinonyl naphthalene sulfonic acid in the presence of imidazoles. Polyhedron 1987. [DOI: 10.1016/s0277-5387(00)80871-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Casas J, Jones MM. Mercury(II) complexes with sulfhydryl containing chelating agents: Stability constant inconsistencies and their resolution. ACTA ACUST UNITED AC 1980. [DOI: 10.1016/0022-1902(80)80052-2] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Abstract
Distribution patterns of added mercury in raw whole milk after equilibration for 30 min and 2 h at 37 C showed a distribution among acid casein, whey proteins, fat globule membrane, and soluble fat globule membrane of 33, 28, 16, and 2%. On the basis of protein content, the fat globule membrane had the highest amount of mercury. Mercury added to milk as mercuric chloride was removed by treatment with thiolated aminoethyl celluloses and reduced human hair. In a 5 min treatment, 70, 43, and 41% of the mercury was removed by thiosuccinylated aminoethyl cellulose, thionitrocarboxyphenylated aminoethyl cellulose, and reduced human hair, respectively, from whole milk initially containing 1 ppm mercury and equilibrated for 2 h at 37 C prior to treatment. After treatment for 60 min, 82, 52, and 64% of the mercury was removed by thiosuccinilated aminoethyl cellulose, thionitrocarboxyphenylated aminoethyl cellulose, and reduced hair, respectively. However, increasing incubation temperature and time prior to treatment decreased the removal efficiencies. Thiosuccinilated aminoethyl cellulose and reduced human hair showed increasing efficiency directly with pH, while thionitrocarboxyphenylated aminoethyl cellulose showed the opposite effect and had higher affinity for mercury at pH 5.5 than at pH 7.5. Moreover, the rate of removal of mercury at 4 C compared to 37 C was much slower. The removal of mercury from soluble casein and soluble whey proteins was more efficient than from micellar casein. Protein, lactose content, and pH of milk were not changed by the polymer treatments.
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