Sequestering ability of some chelating agents towards methylmercury(II)

Abstract

A study on the interactions between CH(3)Hg(+) and some S, N and O donor ligands (2-mercaptopropanoic acid (thiolactic acid (H(2)TLA)), 3-mercaptopropanoic acid (H(2)MPA), 2-mercaptosuccinic acid (thiomalic acid (H(3)TMA)), D,L-penicillamine (H(2)PSH), L-cysteine (H(2)CYS), glutathione (H(3)GSH), N,N'-bis(3-aminopropyl)-1-4-diaminobutane (spermine (SPER)), 1,2,3,4,5,6-benzenehexacarboxylic acid (mellitic acid (H(6)MLT)) and ethylenediaminetetraacetic acid (H(4)EDTA)) is reported. The speciation models in aqueous solution and the possible structures of the complexes formed are discussed on the basis of potentiometric, calorimetric, UV spectrophotometric and electrospray mass spectrometric results. For the CH(3)Hg(+)-S donor ligand systems, the formation of ML(1-z) and MLH(2-z) complex species is observed, together with a diprotonated MLH(2)(3-z) species for CYS(2-), PSH(2-) and GSH(3-) and the mixed hydrolytic one ML(OH)(-z) for TLA(2-) and MPA(2-). The dependence of the stability on ionic strength and on temperature is also analysed. In the other CH(3)Hg(+)-L systems (L = MLT(6-), SPER and EDTA(4-)), ML(1-z), MLH(2-z) and MLH(2)(3-z) complex species are formed, together with the MLH(3)(4-z) species for SPER, the mixed hydrolytic ML(OH)(-z) one for SPER and EDTA, and the M(2)L(2-z) for EDTA only. On the basis of the speciation models proposed, the sequestering ability of the ligands towards methylmercury(II) cation is evaluated. All S donor ligands show a good sequestering power (at 10(-11) mol L(-1) level, in the pH range 4 to 8) following the trend MPA(2-) < PSH(2-) < GSH(3-) < TLA(2-) < CYS(2-) < TMA(3-), while significantly lower is the sequestering ability of MLT, SPER and EDTA (at 10(-3)-10(-5) mol L(-1) level, in the pH range 4 to 8).

Speciation Study on O-Phosphorylethanolamine and O-Phosphorylcholine: Acid–Base Behavior and Mg2+ Interaction

“…The most important peculiarities of MALDI MS-based methods rely in the rapid and sensitive detection of analytes ( Aiello et al, 2020 ; Salvatore et al, 2020 ) and in obtaining the molecular profiling of complex mixtures. Finally, the structures of low molecular weight organic and organometallic compounds can be analyzed and determined by tandem mass spectrometry (MS/MS) experiments ( Falcone et al, 2013 ). The interaction of Mg 2+ with PPC and PEA was explored by MALDI using α–CHCA as the matrix.…”

Thermodynamic data for Pb2+and Zn2+sequestration by biologically important S-donor ligands, at different temperatures and ionic strengths

“…[5][6][7] For this reason, in recent years we have undertaken a detailed study on the acid-base and binding properties of S-donor ligands against some metal and organometallic cations of environmental and biological relevance. [8][9][10][11][12][13][14][15][16] Here we extended the study to the interaction of some sulfur containing aminoacids (see Fig. 1) with a toxic metal, such us Pb 2+ , and an essential metal, such as Zn 2+ , recently studied by thermogravimetric analysis.…”

“…The thermodynamic parameters for the interactions of cys, psh and gsh with Hg 2+ , CH 3 Hg + , (CH 3 ) 2 Sn 2+ , (CH 3 ) 3 Sn + , (C 2 H 5 ) 3 Sn + and (C 3 H 7 ) 3 Sn + were determined in our recent papers. [8][9][10][11][12][13][14][15] Here, we extend the study to the interactions with Pb 2+ and Zn 2+ : these systems have not been widely studied and the only literature thermodynamic data are reported in Table 1. 5,6,[20][21][22][23][24][25][26] The purpose was to define the speciation models (i.e.…”

A Study of the Complexation of Mercury(II) with Dicysteinyl Tetrapeptides by Electrospray Ionization Mass Spectrometry

“…As we have previously mentioned 7,8 , ESI mass spectrometry provides a sensitive analytical tool for an accurate determination of the stoichiometry of mercury and peptide in the mercury-peptide complexes under the specified electrospray ionization condition. However, it is necessary to use additional methods (for example, 1 H, 13 C, 199 Hg NMR spectroscopy, extended X-ray absorption fine structure, or potentiometry [17][18] ) to provide a more accurate determination of the content of complexes in solution.…”