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Nascimento ALA, Figueiredo IM, Botero WG, Santos JCC. Interaction between roxarsone, an organic arsenic compound, with humic substances in the soil simulating environmental conditions. CHEMOSPHERE 2023; 339:139688. [PMID: 37532198 DOI: 10.1016/j.chemosphere.2023.139688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 07/10/2023] [Accepted: 07/30/2023] [Indexed: 08/04/2023]
Abstract
In environmental systems, the soil is a principal route of contamination by various potentially toxic species. Roxarsone (RX) is an arsenic (V) organic compound used to treat parasitic diseases and as an additive for animal fattening. When the animal excretes RX, the residues may lead to environmental contamination. Due to their physicochemical properties, the soil's humic substances (HS) are important in species distribution in the environment and are involved in various specific interaction/adsorption processes. Since RX, an arsenic (V) compound, is considered an emerging contaminant, its interaction with HS was evaluated in simulated environmental conditions. The HS-RX interaction was analyzed by monitoring intrinsic HS fluorescence intensity variations caused by complexation with RX, forming non-fluorescent supramolecular complexes that yielded a binding constant Kb (on the order of 103). The HS-RX interaction occurred through static quenching due to complex formation in the ground state, which was confirmed by spectrophotometry. The process was spontaneous (ΔG < 0), and the predominant interaction forces were van der Waals and hydrogen bonding (ΔH < 0 and ΔS < 0), with an electrostatic component evidenced by the influence of ionic strength in the interaction process. Structural changes in the HS were verified by synchronized and 3D fluorescence, with higher variation in the region referring to the protein-like fraction. In addition, metal ions (except ions Cu(II)) favored HS-RX interaction. When interacting with HS, the RX epitope was suggested by 1H NMR, which indicated that the entire molecule interacts with the superstructure. An enzyme inhibition assay verified the ability to reduce the alkaline phosphatase activity of free and complexed RX (RX-HS). Finally, this work revealed the main parameters associated with HS and RX interaction in simulated environmental conditions, thus, providing data that may help our understanding of the dynamics of organic arsenic-influenced soils.
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Affiliation(s)
- Amanda Luise A Nascimento
- Institute of Chemistry and Biotechnology, Federal University of Alagoas, Campus A.C. Simões, 57072-900, Maceió, Alagoas, Brazil
| | - Isis Martins Figueiredo
- Institute of Chemistry and Biotechnology, Federal University of Alagoas, Campus A.C. Simões, 57072-900, Maceió, Alagoas, Brazil
| | - Wander Gustavo Botero
- Institute of Chemistry and Biotechnology, Federal University of Alagoas, Campus A.C. Simões, 57072-900, Maceió, Alagoas, Brazil
| | - Josué Carinhanha Caldas Santos
- Institute of Chemistry and Biotechnology, Federal University of Alagoas, Campus A.C. Simões, 57072-900, Maceió, Alagoas, Brazil.
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Santos VS, Moura BR, Metzker G, Cornélio ML, Ferreira OP, Mounier SJL, Hajjoul H, Boscolo M, Bisinoti MC, Moreira AB. Increase of Fluorescence of Humic-Like Substances in Interaction with Cd(II): a Photoinduced Charge Transfer Approach. J Fluoresc 2022; 32:1761-1767. [PMID: 35678899 DOI: 10.1007/s10895-022-02978-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Accepted: 05/27/2022] [Indexed: 11/29/2022]
Abstract
Described is the enhancement of fluorescence intensity due to the interaction of a humic-like substance (HLS 1%) extracted from process water (PW) and Cd(II) ions in aqueous solution. Using Canonical Polyadic/Parallel Factor Analysis (CP/PARAFAC), two main components were seen that contributed to fluorescence, the first one increased it and the second one kept it constant in both static and dynamic fluorescence studies. Two-dimensional FTIR analysis indicated that the interaction of HLS 1% and Cd(II) ions occurred in the following order of affinity with the groups: C-O bonds in polysaccharides > C-O bonds in carboxylic acid. The results obtained suggest that the increase in fluorescence intensity and lifetime suggest a photoinduced charge transfer (PCT) between Cd(II) ions and carboxylic acid groups present in HLS 1%.
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Affiliation(s)
- Vinicius S Santos
- Department of Chemistry and Environmental Sciences, Institute of Biosciences, Humanities and Exact Sciences, São Paulo State University (UNESP), São José Do Rio Preto, São Paulo, Brazil
| | - Bernardo R Moura
- Department of Chemistry and Environmental Sciences, Institute of Biosciences, Humanities and Exact Sciences, São Paulo State University (UNESP), São José Do Rio Preto, São Paulo, Brazil
| | - Gustavo Metzker
- Department of Chemistry and Environmental Sciences, Institute of Biosciences, Humanities and Exact Sciences, São Paulo State University (UNESP), São José Do Rio Preto, São Paulo, Brazil
| | - Marinonio L Cornélio
- Department of Physics, Institute of Biosciences, Humanities and Exact Sciences, São Paulo State University (UNESP), São José Do Rio Preto, São Paulo, Brazil
| | - Odair P Ferreira
- Department of Physics, Federal University of Ceará, Fortaleza, Ceará, Brazil
| | - Stéphane J L Mounier
- Univ Toulon, Aix Marseille Univ., CNRS/INSU, IRD, MIO UM 110, Mediterranean Institute of Oceanography, CS, 60584, Toulon, France
| | - Houssam Hajjoul
- Univ Toulon, Aix Marseille Univ., CNRS/INSU, IRD, MIO UM 110, Mediterranean Institute of Oceanography, CS, 60584, Toulon, France
| | - Maurício Boscolo
- Department of Chemistry and Environmental Sciences, Institute of Biosciences, Humanities and Exact Sciences, São Paulo State University (UNESP), São José Do Rio Preto, São Paulo, Brazil
| | - Márcia C Bisinoti
- Department of Chemistry and Environmental Sciences, Institute of Biosciences, Humanities and Exact Sciences, São Paulo State University (UNESP), São José Do Rio Preto, São Paulo, Brazil
| | - Altair B Moreira
- Department of Chemistry and Environmental Sciences, Institute of Biosciences, Humanities and Exact Sciences, São Paulo State University (UNESP), São José Do Rio Preto, São Paulo, Brazil.
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Monteiro ASC, Parat C, Rosa AH, Pinheiro JP. Towards field trace metal speciation using electroanalytical techniques and tangential ultrafiltration. Talanta 2016; 152:112-8. [DOI: 10.1016/j.talanta.2016.01.053] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Revised: 01/22/2016] [Accepted: 01/25/2016] [Indexed: 11/24/2022]
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de Oliveira LK, Melo CDA, Fraceto LF, Friese K, Rosa AH. Interaction of arsenic species with tropical river aquatic humic substances enriched with aluminum and iron. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2016; 23:6205-6216. [PMID: 26606934 DOI: 10.1007/s11356-015-5816-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 11/16/2015] [Indexed: 06/05/2023]
Abstract
The mobility and bioavailability of arsenic (As) are strongly controlled by adsorption/precipitation processes involving metal oxides. However, the organic matter present in the environment, in combination with these oxides, can also play an important role in the cycle of arsenic. This work concerns the interaction between As and two samples of aquatic humic substances (AHS) from tropical rivers. The AHS were extracted as proposed by IHSS, and were characterized by (13)C NMR. The experiments were conducted with the AHS in natura and enriched with metal cations, with different concentrations of As, and complexation capacity was evaluated at three different pH levels (5.0, 7.0, and 9.0). The AHS samples showed similar chemical compositions. The results suggested that there was no interaction between As(III) and AHS in natura or enriched with Al. Low concentrations of As(V) were bound to AHS in natura. For As(III), the complexation capacity of the AHS enriched with Fe was approximately 48 μmol per g of C, while the values for As(V) were in the range 69-80 μmol per grams of C. Fluorescence spectra showed that changes in Eh affected the complexation reactions of As(V) species with AHS.
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Affiliation(s)
- Lilian Karla de Oliveira
- Department of Analytical Chemistry, Institute of Chemistry, UNESP, Rua Prof. Francisco Degni, 55, Araraquara, 18087-180, São Paulo, Brazil.
- Department of Environmental Engineering, UNESP, Av. Três de Março, 511, Sorocaba, 18087-180, São Paulo, Brazil.
| | - Camila de Almeida Melo
- Department of Analytical Chemistry, Institute of Chemistry, UNESP, Rua Prof. Francisco Degni, 55, Araraquara, 18087-180, São Paulo, Brazil
- Department of Environmental Engineering, UNESP, Av. Três de Março, 511, Sorocaba, 18087-180, São Paulo, Brazil
| | - Leonardo Fernandes Fraceto
- Department of Environmental Engineering, UNESP, Av. Três de Março, 511, Sorocaba, 18087-180, São Paulo, Brazil
| | - Kurt Friese
- UFZ-Helmholtz Centre for Environmental Research, Bruckstrasse 3a, 39114, Magdeburg, Germany
| | - André Henrique Rosa
- Department of Environmental Engineering, UNESP, Av. Três de Março, 511, Sorocaba, 18087-180, São Paulo, Brazil
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Cunha GDC, Goveia D, Romão LPC, de Oliveira LC. Effect of the competition of Cu(II) and Ni(II) on the kinetic and thermodynamic stabilities of Cr(III)-organic ligand complexes using competitive ligand exchange (EDTA). JOURNAL OF ENVIRONMENTAL MANAGEMENT 2015; 154:259-265. [PMID: 25745843 DOI: 10.1016/j.jenvman.2015.02.038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2015] [Accepted: 02/20/2015] [Indexed: 06/04/2023]
Abstract
The effect of competition of Cu(II) and Ni(II) on the kinetic stability of Cr(III) complexed with natural organic matter (NOM) was characterized using EDTA exchange with single-stage tangential-flow ultrafiltration. For a water sample from Serra de Itabaiana, 3% of spiked Cr(III) was exchanged, while for a sample from the Itapanhaú River, 7, 10, 10, and 21% was exchanged in experiments using Cr(III) alone and in combination with Cu(II), Ni(II), or Cu(II) + Ni(II), respectively. Times required to reach exchange equilibrium with EDTA were less than 360 min. The influence of competition from Ni(II) and Cu(II) on the availability of complexed Cr(III) was low, demonstrating preference of the ligand sites for Cr(III). This was correlated with sample humification, as confirmed by EPR and (13)C NMR analyses. Exchange efficiency was in the order Cu > Ni > Cr, and the process could be readily described by first order kinetics, with average rate constants of 0.35-0.37 h(-1).
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Affiliation(s)
- Graziele da Costa Cunha
- Department of Chemistry, Federal University of Sergipe (UFS), 49100-000 São Cristovão, SE, Brazil
| | - Danielle Goveia
- Experimental Campus of Itapeva, São Paulo State University (UNESP), 18409-010, Itapeva, SP, Brazil
| | | | - Luciana Camargo de Oliveira
- Department of Physical, Chemistry and Mathematics, Federal University of São Carlos (UFSCar), 18052-780, Sorocaba, SP, Brazil
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Botero WG, de Oliveira LC, Rocha JC, Rosa AH, Dos Santos A. Peat humic substances enriched with nutrients for agricultural applications: competition between nutrients and non-essential metals present in tropical soils. JOURNAL OF HAZARDOUS MATERIALS 2010; 177:307-311. [PMID: 20042279 DOI: 10.1016/j.jhazmat.2009.12.033] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2009] [Revised: 12/02/2009] [Accepted: 12/05/2009] [Indexed: 05/28/2023]
Abstract
Improved agricultural productivity, and reduction of environmental impacts, require studies of the interactions between different soil components. Fertilizers marketed as "organic" or "natural", such as peats or humic substances (HS) extracted from peats, are enriched with macro and micronutrients that, according to the manufacturers, are released to the plant in accordance with its needs. This work investigates the complexation capacity of HS for macro and micronutrient metal species, considering the competition, for HS complexation sites, between non-essential metals (aluminium and lead), present in the soil, and the nutrients. Humic substances were found to possess strong affinities for Pb(II) and Al(III), forming stable complexes, with concomitant release of complexed nutrients. Although HS are already used commercially as organic fertilizers, further studies of methods of HS enrichment, aimed at avoiding losses, are highly desirable from environmental and economic perspectives.
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Goveia D, Lobo FA, Burba P, Fraceto LF, Dias Filho NL, Rosa AH. Approach combining on-line metal exchange and tangential-flow ultrafiltration for in-situ characterization of metal species in humic hydrocolloids. Anal Bioanal Chem 2010; 397:851-60. [DOI: 10.1007/s00216-010-3547-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2009] [Revised: 02/03/2010] [Accepted: 02/05/2010] [Indexed: 10/19/2022]
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8
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Polyakov EV. Behavior of ionic and colloid forms of microelements in colloidal chemical extraction from humic acid solutions. RADIOCHEMISTRY 2007. [DOI: 10.1134/s1066362207040194] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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9
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Zih-Perényi K, Lásztity A, Pusztai S. Study of interference of pharmaceuticals with complexing characteristics in solid phase microextraction of lead on chelating celluloses. Microchem J 2007. [DOI: 10.1016/j.microc.2006.04.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Burba P, Geltenpoth H, Nolte J. Ultrafiltration behavior of selected pharmaceuticals on natural and synthetic membranes in the presence of humic-rich hydrocolloids. Anal Bioanal Chem 2005; 382:1934-41. [PMID: 16021427 DOI: 10.1007/s00216-005-3296-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2005] [Revised: 04/14/2005] [Accepted: 04/20/2005] [Indexed: 11/25/2022]
Abstract
The separation behavior of the frequently administered pharmaceuticals sulfamethoxazol (Sulfa), carbamazepine (Carba), diclofenac (Diclo), and ibuprofen (Ibu) on different natural and synthetic ultrafiltration membranes was studied. Commercially available cattle intestine natural membranes (NM), polyethersulfone (PES), and regenerated cellulose-based (RC) flat membranes (nominal cut-off 1 kDa) have been investigated as ultrafiltration membranes in a small tangential-flow ultrafiltration unit (TF-UF). First, the nominal cut-off of the NM membranes under study was assessed at approximately 5 kDa, by using polystyrenesulfonate standards for pore-size classification at low TF-UF pressure (0.25 x 10(5) Pa). Working pressures of >1.5 x 10(5) Pa strongly increased the cut-off of NM, in contrast with that of PES and RC membranes. Sulfa, Carba, Diclo and Ibu (1 mg L(-1) each) in colloid-free aqueous solutions (400 mg L(-1) NaCl) completely permeated through NM membranes, but less through PES and RC, which had particular sorption capability towards Diclo. The drugs were routinely determined by using high-performance liquid chromatography (HPLC). Detailed TF-UF investigation of drug retention on NM in the presence of humic hydrocolloids revealed strong interactions between aquatic humic substances (HS) and Diclo and Ibu (but not with Sulfa and Carba) causing retention of up to 80% of Diclo and Ibu, probably because of their binding to macromolecular HS. The standard deviation (SD) of both drug and HS permeation through a single NM was between 2.5 (Sulfa) and 4.0% (Diclo), in contrast with the SD of permeation through separate membranes taken from different lots [SD up to 14.0% (Diclo)], presumably caused by natural variation of the studied NM. Accordingly, membrane filtration of drug-containing water samples on cattle intestines enables both analyte/matrix separations for Carba and Sulfa in the presence of humic colloids and analytical discrimination between free and colloid-bound Diclo and Ibu fractions.
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Affiliation(s)
- Peter Burba
- ISAS, Institute for Analytical Sciences, Bunsen-Kirchhoff-Str. 11, 44139 Dortmund, Germany
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Juhna T, Klavins M, Eglite L. Sorption of humic substances on aquifer material at artificial recharge of groundwater. CHEMOSPHERE 2003; 51:861-868. [PMID: 12697176 DOI: 10.1016/s0045-6535(03)00108-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Experiments in batch equilibrium system were carried out to evaluate the importance of physical and chemical factors determining the sorption efficiency of humic substances (HS) on aquifer material, which has been used for artificial recharge of groundwater (ARG) in drinking water production. Results showed that an increase of the amount of clay in the aquifer material and a decrease of pH in water increased the sorption efficiency. The sorption of higher molecular weight, more hydrophobic and aromatic HS (Aldrich and forest soil humic acids) were greater than the sorption of acidic HS (river fulvic acids), either on the aquifer material or to its representative sorbing phases, clay and organic matter. The sorption on the aquifer material was largely due to physical sorption (hydrophobic attractions). This study showed the importance of HS composition on their removal during ARG and contributed to an understanding of the HS sorption mechanisms in this process.
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Affiliation(s)
- Talis Juhna
- Department of Environmental Engineering, Luleå University of Technology, SE 97187, Sweden
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Castiñeira MDM, Burba P, Jakubowski N, Andersson J. Size fractionation of non-volatile dissolved organic compounds and metal species in German white wines by combining on-line tangential-flow multistage ultrafiltration, a home-built carbon analyser, and inductively coupled plasma mass spectrometry. Anal Bioanal Chem 2003; 376:174-81. [PMID: 12677340 DOI: 10.1007/s00216-003-1867-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2003] [Accepted: 02/12/2003] [Indexed: 10/20/2022]
Abstract
Organic metal species and their size fractions in three German white wines were characterized by combining multistage ultrafiltration (MST-UF), determination of non-volatile dissolved organic carbon (NV-DOC) by a home-built carbon analyser, and metal quantification by inductively coupled plasma mass spectrometry (ICP-MS). First, NV-DOC and metal species in selected "dry" German white wines were fractionated on-line using MST-UF in the size range of >100 kDa to <1 kDa. For this purpose a 20 mL sample of the wine under study diluted 1:10 with high-purity water was processed through a cascade system of hydrophilized polyethersulfone-based flat membranes of decreasing cut-off (100, 50, 10, 5, and 3 kDa). An aliquot of the fraction <3 kDa was additionally processed through a commercial UF tube (MidGee system, cut-off: 1 kDa) to obtain low-molecular size fractions also. A home-built carbon analyser was applied to determine NV-DOC in the wines and their size fractions. The NV-DOC found in a German reference wine and its size fractions was as follows: total NV-DOC: 8.97 mg mL(-1); F(1) (>100 kDa), 0.15%; F(2) (50-100 kDa), 0.44%; F(3) (10-50 kDa), 0.74%; F(4) (5-10 kDa), 0.76%; F(5) (5-3 kDa), 0.7%; F*(6) (3-1 kDa), 0.9%; F(7) (<1 kDa), 81.6% (related to total NV-DOC). The NV-DOC recovery was 85.2%. Accordingly, most of the NV-DOC in this wine consists of low-molecular mass organic compounds of <1 kDa, presumably carboxylic acids as typical in wine. Parallel metal determinations in these wines and their fractions were performed by ICP-MS. The measurements showed that the major part of the metals investigated, up to 25 elements, were dissolved in the size fraction of <1 kDa except Ba, Sr and Pb which appeared also in other fractions. In addition, conventional UV-VIS spectroscopy was applied to characterise the studied wines and their size fractions. According to this, the UV absorbance between 254 and 280 nm of these white wines shows a parallel trend to their NV-DOC.
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Affiliation(s)
- Maria del Mar Castiñeira
- Institut für Spektrochemie und Angewandte Spektroskopie, Bunsen-Kirchhoff-Strasse 11, 44139 Dortmund, Germany.
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Romão LPC, Castro GR, Rosa AH, Rocha JC, Padilha PM, Silva HC. Tangential-flow ultrafiltration: a versatile methodology for determination of complexation parameters in refractory organic matter from Brazilian water and soil samples. Anal Bioanal Chem 2003; 375:1097-100. [PMID: 12733022 DOI: 10.1007/s00216-002-1728-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2002] [Revised: 10/30/2002] [Accepted: 11/27/2002] [Indexed: 11/29/2022]
Abstract
In this work the copper(II) complexation parameters of aquatic organic matter, aquatic and soil humic substances from Brazilian were determined using a new versatile approach based on a single-stage tangential-flow ultrafiltration (TF-UF) technique (cut-off 1 kDa) and sensitive atomic spectrometry methods. The results regarding the copper(II) complexation capacity and conditional stability constants obtained for humic materials were compared with those obtained using direct potentiometry with a copper-ion-selective electrode. The analytical procedure based on ultrafiltration is a good alternative to determine the complexation parameters in natural organic material from aquatic and soil systems. This approach presents additional advantages such as better sensibility, applicability for multi-element capability, and its possible to be used under natural conditions when compared with the traditional ion-selective electrode.
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Affiliation(s)
- L P C Romão
- Universidade Federal de Sergipe, Jd. Rosa Elze, s/n, 49100-000, São Cristóvão-SE, Brazil.
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14
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Abstract
Separation methods are widely used to isolate humic substances (HSs), to fractionate them before further investigation, and to obtain information about their structure and properties. Among the chromatographic methods, techniques based on a size-exclusion effect appear to be most useful, as they allow us to relate elution data to the molecular mass distribution of HSs. The limitations of this approach are discussed in this review. Gas chromatography with mass spectrometric detection is typically used to identify the products of pyrolysis or thermochemolysis of HSs; this technique is considered most important in the structural investigation of HSs. Electrophoretic methods (especially capillary zone electrophoresis) provide detailed characterization of HSs, but it is very difficult to relate the electrophoretic data to any specific subfraction, structure or properties of HSs. The electrophoretic patterns are often called "fingerprints" and can potentially be used for the identification and classification of HSs. This is limited, however, by the great diversity of the procedures employed and by the low degree of harmonization--no data on reproducibility and between-laboratory comparability are available. The same holds true, to a certain degree, for most methods utilized for the characterization of HSs. Separation methods play an important role in the examination of the interactions of HSs with heavy metals and other chemical pollutants. They allow us to determine binding constants and other data necessary to predict the mobility of chemical pollutants in the environment.
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Affiliation(s)
- Pavel Janos
- Faculty of Environmental Studies, University of Jan Evangelista Purkyne, Králova Vysina 7, 400 96 Ustí nad Labem, Czech Republic.
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Rocha JC, Rosa AH, Van den Bergh J, Burba P. Characterization of humic-rich hydrocolloids and their metal species by means of competing ligand and metal exchange--an on-site approach. JOURNAL OF ENVIRONMENTAL MONITORING : JEM 2002; 4:799-802. [PMID: 12400935 DOI: 10.1039/b203051a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An improved on-site characterization of humic-rich hydrocolloids and their metal species in aquatic environments was the goal of the present approach. Both ligand exchange with extreme chelators (diethylenetetraaminepentaacetic acid (DTPA), ethylendiaminetetraacetic acid (EDTA)) and metal exchange with strongly competitive cations (Cu(II) were used on-site to characterize the conditional stability and availability of colloidal metal species in a humic-rich German bogwater lake (Venner Moor, Münsterland). A mobile time-controlled tangential-flow ultrafiltration technique (cut-off: 1 kDa) was applied to differentiate operationally between colloidal metal species and free metal ions, respectively. DOC (dissolved organic carbon) and metal determinations were carried out off-site using a home-built carbon analyzer and conventional ICP-OES (inductively-coupled plasma-optical emission spectrometry), respectively. From the metal exchange equilibria obtained on-site the kinetic and thermodynamic stability of the original metal species (Fe, Mn, Zn) could be characterized. Conditional exchange constants Kex obtained from aquatic metal species and competitive Cu(II) ions follow the order Mn > Zn > > Fe. Obviously, Mn and Zn bound to humic-rich hydrocolloids are very strongly competed by Cu(II) ions, in contrast to Fe which is scarcely exchangeable. The exchange of aquatic metal species (e.g. Fe) by DTPA/EDTA exhibited relatively slow kinetics but rather high metal availabilities, in contrast to their Cu(II) exchange.
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Affiliation(s)
- Julio C Rocha
- Instituto de Química da Universidade Estadual Paulista-UNESP, Araraquara, SP, Brazil.
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