Voltammetric behaviour of marine hydrophobic copper complexes: effect of adsorption processes at a mercury electrode

Scarano, Gioacchino; Bramanti, Emilia

doi:10.1016/0003-2670(93)85098-5

Cited by 23 publications

(13 citation statements)

References 29 publications

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“…As a significant part of NOM usually exhibit the properties of SAS [32], this process is likely to occur when dealing with real sample in ASV. In the literature it has been reported how the adsorption of SAS influences the electrochemical reactions of copper [25][26][27] and also that the desorption of adsorbed SAS occurs at more negative potentials, producing well-resolved copper peak [25,31].…”

Section: Introductionmentioning

confidence: 99%

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Speciation of trace metals in natural waters: The influence of an adsorbed layer of natural organic matter (NOM) on voltammetric behaviour of copper

Louis

Cmuk

Omanović

et al. 2008

Analytica Chimica Acta

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The influence of an adsorbed layer of the natural organic matter (NOM) on voltammetric behaviour of copper on a mercury drop electrode in natural water samples was studied. The adsorption of NOM strongly affects the differential pulse anodic stripping voltammogram (DPASV) of copper, leading to its distortion. Phase sensitive ac voltammetry confirmed that desorption of adsorbed NOM occurs in general at accumulation potentials more negative than -1.4V. Accordingly, an application of negative potential (-1.6V) for a very short time at the end of the accumulation time (1% of total accumulation time) to remove the adsorbed NOM was introduced in the measuring procedure. Using this protocol, a well-resolved peak without interferences was obtained. It was shown that stripping chronopotentiogram of copper (SCP) in the depletive mode is influenced by the adsorbed layer in the same manner as DPASV. The influence of the adsorbed NOM on pseudopolarographic measurements of copper and on determination of copper complexing capacity (CuCC) was demonstrated. A shift of the peak potential and the change of the half-peak width on the accumulation potential (for pseudopolarography) and on copper concentration in solution (for CuCC) were observed. By applying a desorption step these effects vanished, yielding different final results.

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Section: Introductionmentioning

confidence: 99%

“…The interferences in voltammetry [3,[23][24][25][26][27][28][29][30][31] are well known, and one important problem is adsorption of surface active substances (SAS) on the electrode surface. As a significant part of NOM usually exhibit the properties of SAS [32], this process is likely to occur when dealing with real sample in ASV.…”

Section: Introductionmentioning

confidence: 99%

Speciation of trace metals in natural waters: The influence of an adsorbed layer of natural organic matter (NOM) on voltammetric behaviour of copper

Louis

Cmuk

Omanović

et al. 2008

Analytica Chimica Acta

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“…Fortunately, such problems could be effectively eliminated by applying very negative "desorption potential" (e.g. −1.5 V) for a short period of time (1% of total accumulation time) at the end of the accumulation period [10,29,30]. Without this desorption step, a broad and relatively high peak overlapping with the oxidation peak of copper appears, which is usually assigned to copper peak by most of the authors.…”

Section: Introductionmentioning

confidence: 97%

“…The most noticed complication in ASV is found to be an adsorption of surface active substances (SAS) originating from NOM on the surface of the electrode [27][28][29]. Fortunately, such problems could be effectively eliminated by applying very negative "desorption potential" (e.g.…”

Section: Introductionmentioning

confidence: 98%

Significance of data treatment and experimental setup on the determination of copper complexing parameters by anodic stripping voltammetry

Omanović

Garnier

Louis

et al. 2010

Analytica Chimica Acta

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Different procedures of voltammetric peak intensities determination, as well as various experimental setups were systematically tested on simulated and real experimental data in order to identify critical points in the determination of copper complexation parameters (ligand concentration and conditional stability constant) by anodic stripping voltammetry (ASV). Varieties of titration data sets (Cu(measured)vs. Cu(total)) were fitted by models encompassing discrete sites distribution of one-class and two-class of binding ligands (by PROSECE software). Examination of different procedures for peak intensities determination applied on voltammograms with known preset values revealed that tangent fit (TF) routine should be avoided, as for both simulated and experimental titration data it produced an additional class of strong ligand (actually not present). Peak intensities determination by fitting of the whole voltammogram was found to be the most appropriate, as it provided most reliable complexation parameters. Tests performed on real seawater samples under different experimental conditions revealed that in addition to importance of proper peak intensities determination, an accumulation time (control of the sensitivity) and an equilibration time needed for complete complexation of added copper during titration (control of complexation kinetics) are the keypoints to obtain reliable results free of artefacts. The consequence of overestimation and underestimation of complexing parameters is supported and illustrated by the example of free copper concentrations (the most bioavailable/toxic specie) calculated for all studied cases. Errors up to 80% of underestimation of free copper concentration and almost two orders of magnitude overestimation of conditional stability constant were registered for the simulated case with two ligands.

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“…The high negative potential was selected in order to avoid the interferences produced by the adsorption of dissolved organic matter on the electrode surface (Scarano and Bramanti, 1993).…”

Section: Methodsmentioning

confidence: 99%

A voltammetric study of copper-ion binding to the cell surface of the marine alga

Scarano

Morelli

1993

Chemical Speciation & Bioavailability

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The binding of copper ion to the surfaces of the marine diatom Phaeodactylum tricornutum was studied in seawater pH 8. The cell wall complexing capacity and the average surface complex formation constant were determined by voltammetric titration curves. The presence of biotic particles at a concentration of 2. 7 x 10 6 cells ml -1 does not hinder the measurement of stripping currents and the voltammetric fraction of non-reducible copper is the same as the copper bound to the cell surfaces as measured by atomic absorption spectrometry.

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Voltammetric behaviour of marine hydrophobic copper complexes: effect of adsorption processes at a mercury electrode

Cited by 23 publications

References 29 publications

Speciation of trace metals in natural waters: The influence of an adsorbed layer of natural organic matter (NOM) on voltammetric behaviour of copper

Speciation of trace metals in natural waters: The influence of an adsorbed layer of natural organic matter (NOM) on voltammetric behaviour of copper

Significance of data treatment and experimental setup on the determination of copper complexing parameters by anodic stripping voltammetry

A voltammetric study of copper-ion binding to the cell surface of the marine alga

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