Electrochemical Methods for Speciation of Trace Elements in Marine Waters. Dynamic Aspects

Mota, A.M.; Pinheiro, José Paulo; Gonçalves, Maria Eduarda

doi:10.1021/jp2124636

Cited by 31 publications

(19 citation statements)

References 114 publications

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“…Introduction well as dynamic information (such as kinetic rate constants and diffusion coefficients 48 [16]). However, the correct signal interpretation can be difficult in natural media 49 water column [29], stormwater [42]), and identity (e.g.…”

Section: List Of Nomenclature and Abbreviationsmentioning

confidence: 99%

“…Additionally, the slope 147 variation of the SSCP wave provides information on the degree of heterogeneity of the 148 complexing ligands [80]. 149 SCP in environmental analysis was reviewed in 2007 [81], while SSCP applications in 150 the development of chemodynamics theory and applications in seawater analysis were 151 reviewed in 2012 [16]. We are focusing here on published works from 2012 which can 152 be clustered in four groups: SCP/SSCP technical and methodological developments; 153 trace metal interaction with humic matter; nanoparticle studies and, finally, trace metal 154 bioavailability studies (see Table 1 for applications).…”

Section: Scp/sscp (Scanned Stripping Chronopotentiometry)mentioning

confidence: 99%

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A review on electrochemical methods for trace metal speciation in environmental media

Companys

Galceran

Pinheiro

et al. 2017

Current Opinion in Electrochemistry

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11Trace metal speciation is key to understand/predict bioavailability and potential toxicity 12 of metals to biota and will, undoubtedly, be incorporated in future regulations. 13Electroanalytical methods have a role to play in such development: they offer a wide 14 range of advantages such as speed, portability, economy, solid interpretation 15 backgrounds and low limits of quantification. This review focusses on three selected 16 stripping techniques: Competitive-Ligand Exchange -Cathodic Stripping Voltammetry 17 (CLE-CSV), Scanned Stripping Chrono-Potentiometry (SSCP) and AGNES (Absence 18 of Gradients and Nernstian Equilibrium Stripping) reporting their working principles, 19 characteristics (strong and weak points) and recent applications to systems of 20 environmental relevance (such as seawaters, freshwaters or soil extracts). 21 22 23 24 Keywords: speciation, availability, electroanalysis, electrochemistry, heavy metal, 25 CLE-CSV, SSCP, AGNES 26 27 published in Current Opinion 3 (2017) 144-162 33 Speciation (i.e. the distribution of an element among its different chemical forms[1]) 34 has been recognised as a key factor for trace metal (bio)availability to biota, as 35 postulated by hegemonic ecotoxicological paradigms such as the Free Ion Activity 36 Model (FIAM) [2] or the Biotic Ligand Model (BLM)[3], both assuming that the free 37 ion is the only bioavailable species. The limits of these models have recently been 38 reviewed [4], highlighting numerous cases where specific fractions of metal complexes 39 can be internalized, either directly or through the dissociation of labile complexes. Thus, 40there is a need to design, develop, apply and interpret analytical techniques able to 41 provide reliable speciation information [5][6][7] that can be used by regulatory bodies. 42Although there are numerous non-electrochemical techniques [5][6][7][8][9][10][11][12][13], those that are 43 provide attractive possibilities such as speed of analysis, low-cost and miniaturization in 44 view to on-site (and in-situ) measurements [14], and can also provide thermodynamic 45 (i.e. equilibrium) information (such as the amount of the free metal, the amount of 46 complexing sites, the stoichiometry of complexes and their stability constants [15]) as 47 [16;17]. Stripping techniques, due to their low detection limits, are well suited for 50 environmental analysis. They are two-stage techniques, where the first stage is a 51 deposition step that accumulates the analyte (at the electrode surface or in its volume), 52 followed by a second stage that quantifies this analyte. Anodic Stripping Voltammetry 53 (ASV), in its multiple variants, is the most popular and has the advantage to possibly be 54 measuring a potentially bioavailable fraction of the metal, as shown again recently 55 [18;19]. 56 57 published in Current Opinion 3 (2017) 144-162 This critical evaluation focusses on three techniques that are known powerful tools for 58 metal speciation: AGNES (Absence of Gradients and Nernstian Equilibrium Stripping) 59 and SSCP...

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Section: List Of Nomenclature and Abbreviationsmentioning

confidence: 99%

Section: Scp/sscp (Scanned Stripping Chronopotentiometry)mentioning

confidence: 99%

A review on electrochemical methods for trace metal speciation in environmental media

Companys

Galceran

Pinheiro

et al. 2017

Current Opinion in Electrochemistry

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“…As noted above, there may theoretical reasons for this. [47] A way forward would be a concerted effort to compare techniques, building on previous work and ideas, [13,[53][54][55] but covering a wider and more representative range of conditions and metals.…”

Section: Future Researchmentioning

confidence: 99%

Metal speciation from stream to open ocean: modelling v. measurement

Tipping¹,

Lofts²,

Stockdale³

2016

Environ. Chem.

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Environmental context. The chemical speciation of metals strongly influences their transport, fate and bioavailability in natural waters. Analytical measurement and modelling both play important roles in understanding speciation, while modelling is also needed for prediction. Here, we analyse a large set of data for fresh waters, estuarine and coastal waters, and open ocean water, to examine how well measurements and modelling predictions agree.Abstract. We compiled a data set of ,2000 published metal speciation measurements made on samples of fresh waters, estuarine and coastal waters, and open ocean waters. For each sample, we applied the chemical speciation model WHAM7 to calculate the equilibrium free metal ion concentrations, [M] (mol L À1 ), amounts of metal bound by dissolved organic matter (DOM), n (mol g À1 ), and their ratio n/[M] (L g À1 ), which is a kind of 'local' partition coefficient. Comparison of the measured and predicted speciation variables for the whole data set showed that agreements are best for fresh waters,

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“…81 Em 2017, Town et al 82 questionam a definição da espessura da camada de reação num sistema coloidal sugerindo que a cinética intrapartícula afeta a reatividade na superfície do eletrodo. 86 reportaram os principais desenvolvimentos teóricos na interpretação das características cinéticas da interconversão de espécies de complexos metálicos considerando três aspectos distintos: o efeito de protonação do ligante, a ligação iônica com macromoléculas fortemente carregadas (por exemplo, os ácidos fúlvicos) e a introdução da teoria dinâmica para a ligação de metal em dispersões coloidais. 12 Finalmente, em 2017, van Leeuwen et al 87 apresentaram uma revisão crítica sobre a cinética de associação de cátions com diferentes tipos de nanopartículas, identificando a contribuição do campo elétrico criado pelas cargas da partícula e identificando os fatores que determinam qual a etapa limitante do processo global de associação/ dissociação.…”

Section: As Principais Linhas Do Desenvolvimento Teórico Da Especiaçãunclassified

“…Algumas revisões críticas foram publicadas sobre SCP, 88 comparando-a com outras técnicas não-eletroquímicas 89,90 ou com outras técnicas eletroanalíticas. 86,91 Todavia, o número de estudos em que o foco é a especiação dinâmica é menor, devido à maior dificuldade da interpretação desses resultados e ao menor número de modelos teóricos adequados a descrevê-los. Uma boa parte destes estudos tem sido realizada para comprovar as teorias que abordamos no tópico anterior, não sendo necessariamente repetida aqui.…”

Section: Exemplos De Estudos De Especiação Dinâmica Em Sistemas Modelunclassified

Especiação Dinâmica De Metais Traço Em Ambiente Aquático Usando Cronopotenciometria De Redissolução Anódica

Monteiro¹,

Goveia²,

Rotureau³

et al. 2018

Quim. Nova

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Recebido em 26/01/2018; aceito em 12/04/2018; publicado na web em 22/05/2018 DYNAMIC SPECIATION OF TRACE METALS IN AQUATIC ENVIRONMENT USING ANODIC STRIPPING CHRONOPOTENTIOMETRY. The contamination of natural environments by trace metals has several adverse effects on human health, which is mainly due to the high toxicity, persistence and reactivity of these species in the environment. To understand the bioavailability of trace metals, it is necessary to know the speciation in equilibrium and the dynamic behavior of the system. In this context, the present work aims to present a bibliographic review about the potentialities of the Stripping Chronopotentiometry (SCP) and Stripping Chronopotentiometry at Scanned Deposition Potential (SSCP) in the study of dynamic trace metal speciation. These techniques have low detection limits and do not suffer interference due to the adsorption of organic matter on the surface of the working electrode. Coupling these techniques with the Absence of Gradients and Nernstian Equilibrium Stripping (AGNES) enables simultaneous determination of free ions, complexation equilibrium constants and diffusion coefficients of the complexes, thus providing information on the dynamic and heterogeneity of the metal complexes in the presence of macromolecules or particles. In this paper we will present the theory of dynamic speciation of trace metals, a detailed description of how to use the techniques to obtain this information, and examples of application in model systems and natural samples.Keywords: metal complexes; metal ions; lability; redissolution techniques; deposition time. INTRODUÇÃOO interesse no estudo de metais traço em solução provém da elevada toxicidade, persistência e reatividade de muitos destes no ambiente. Em ambientes aquáticos naturais, os íons metálicos podem se distribuir em diferentes espécies como resultado das interações com componentes da matriz (matéria orgânica, partículas inorgâni-cas) e das características físico-químicas (temperatura, força iônica, pH, potencial redox, presença de outros íons) do meio. A maioria das espécies formadas tem caráter polifuncional e polieletrolítico, apresentando ampla faixa de constantes de velocidade de formação/ dissociação e de tamanhos, que controlam a biodisponibilidade, toxicidade e mobilidade dos íons metálicos. 1O estudo da distribuição dessas espécies é denominado de especiação de metais. O termo especiação foi definido como a descrição da abundância de um elemento numa amostra (distribuição da espé-cie), enquanto a análise de especiação se refere aos procedimentos analíticos de identificação e/ou medida quantitativa de uma ou mais espécies químicas numa amostra. Cada uma destas espécies pode se comportar de forma diferente em termos de mobilidade e biodisponibilidade em sistemas aquáticos naturais, portanto, estão sujeitas à mudança de condições e praticamente nunca atingem o equilíbrio químico. Isto torna o estudo da especiação muito mais complicado, uma vez que se faz necessária uma compreensão da cinética das reações do ...

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Electrochemical Methods for Speciation of Trace Elements in Marine Waters. Dynamic Aspects

Cited by 31 publications

References 114 publications

A review on electrochemical methods for trace metal speciation in environmental media

A review on electrochemical methods for trace metal speciation in environmental media

Metal speciation from stream to open ocean: modelling v. measurement

Especiação Dinâmica De Metais Traço Em Ambiente Aquático Usando Cronopotenciometria De Redissolução Anódica

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