Ligand Size Polydispersity Effect on SSCP Signal Interpretation

Rocha, Luciana S.; Botero, Wander Gustavo; Alves, Nuno G.; Moreira, José A.; Costa, Ana M. Rosa da; Pinheiro, José Paulo

doi:10.1016/j.electacta.2015.03.035

Cited by 9 publications

(9 citation statements)

References 19 publications

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“…155 SSCP was first used with solid electrodes for the study of Pb(II) speciation using 156 bismuth electrodes [82]. Pb(II) speciation in seawater required attention to the correct interpretation of the calibration, due to the formation of PbClx complexes [83], while 158 ligand size polydispersity was investigated using the binding of Pb(II) and Cd(II) to 159 three different sizes of otherwise identical polymers [84]. The study of Cd(II) binding 160 by clay minerals provided interesting dynamic information [85] and, finally, the effect 161 of temperature in the lability of Cd(II) and Pb(II) complexes was investigated [86].…”

Section: Scp/sscp (Scanned Stripping Chronopotentiometry)mentioning

confidence: 99%

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

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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: 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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“…The Hg film electrode (thickness of 28 nm) was prepared following the procedure described by Rocha el al. 30 . AGNES parameters were: and r=0.997) film electrodes.…”

Section: Speciation Resultsmentioning

confidence: 99%

“…Samples of poly(styrenesulfonate) of 4, 10, and 30 kDa were obtained by reversible addition-fragmentation chain transfer (RAFT) polymerization of sodium styrenesulfonate in a water/ethanol solution, using S-(Thiobenzoyl)-thioglycolic acid as chain transfer agent (CTA) and 4,4'-Azobis(4-cyanovaleric acid) as radical initiator 29 . Further details regarding the synthesis of 4000 Da (PSS)n−COOH are described elsewhere 30 .…”

Section: Synthesis Of Monodisperse Charged 4000 Da (Pss)n−cooh Polymermentioning

confidence: 99%

Determination of the Free Metal Ion Concentration Using AGNES Implemented with Environmentally Friendly Bismuth Film Electrodes

et al. 2015

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Ex situ plated Bi film electrodes (Bi-FE) have been employed, for the first time, to measure the free concentration of Pb(II) in aqueous solutions using absence of gradients and Nernstian equilibrium stripping (AGNES) with stripping chronopotentiometry (SCP) quantification. The amount of deposited Pb°, below a certain threshold, follows a Nernstian relationship with the applied potential. This threshold can be interpreted as the frontier of transition from surface deposition to solid (bulk) formation of Pb°. AGNES with Bi-FE yielded a very good detection limit (3σ) for Pb(II) of 6.0 × 10(-9) M with an applied gain of 398 and a deposition time of 400 s. The ability of the Bi film electrode to perform speciation measurements was demonstrated for Pb(II)-PSS and Pb(II)-IDA systems. The measured values with the Bi-FE were in good agreement with the values obtained using the Hg film electrode and/or the values reported in the literature.

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“…Most of the experimental results used in this paper were already published, namely the cadmium and lead experiments with carboxyl terminated polystyrene sulfonate (PSS-COOH) at pH 4 were presented in Rocha et al [30], the cadmium binding by Laurentian Fulvic Acid (LFA) and fully purified humic acid (FPHA) appeared in Janot et al [31] and in Botero et al [32]. In this section, we will only describe briefly the experiments dealing with cadmium binding to carboxyl terminated polystyrene sulfonate (PSS-COOH) at pH 6.5 and the cadmium binding to Sorocabinha fulvic acid.…”

Section: Methodsmentioning

confidence: 99%

Full wave analysis of stripping chronopotentiometry at scanned deposition potential (SSCP): Obtaining binding curves in labile heterogeneous macromolecular systems for any metal-to-ligand ratio

Pinheiro

Galceran

Rotureau

et al. 2020

Journal of Electroanalytical Chemistry

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The different deposition potentials applied in Scanned Stripping ChronoPotentiometry (SSCP) probe different values of the free metal and complex concentrations at the electrode surface. The knowledge of these concentrations gives access to a relevant window of the binding curve of a metal to a homogeneous or heterogeneous ligand. Here, a suitable mathematical treatment for the determination of these surface concentrations, when using a mercury thin film rotating disk electrode, is reported. The proposed procedure does not require ligand excess conditions and takes advantage of the knowledge of the free metal ion concentration in the bulk solution provided by the technique AGNES (Absence of Gradients and Nernstian Equilibrium Stripping). It is experimentally shown that the information derived from the SSCP points (i.e. at different deposition potentials in a unique solution) is consistent with the speciation results yielded by the technique AGNES in pertinent solutions prepared within a range of metal-to-ligand ratios. Successful examples with polystyrene sulfonate, Laurentian Fulvic acid and a peat humic acid are reported. It is concluded that, by running consecutively SSCP and AGNES in a single solution, speciation information corresponding to different compositions (i.e. those locally generated at the electrode JELECHEM-D-20-00386 second_revision.docx 30/06/20 2/35 surface by the end of the deposition step) can be retrieved, this enabling an easy determination of the binding curve.

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Ligand Size Polydispersity Effect on SSCP Signal Interpretation

Cited by 9 publications

References 19 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

Determination of the Free Metal Ion Concentration Using AGNES Implemented with Environmentally Friendly Bismuth Film Electrodes

Full wave analysis of stripping chronopotentiometry at scanned deposition potential (SSCP): Obtaining binding curves in labile heterogeneous macromolecular systems for any metal-to-ligand ratio

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