Minimization of Electrode Adsorption Effects: The Cadmium–Humic Acid System Studied by Phase Sensitive Alternating Current Polarography

Garrigosa, Anna Maria; Ariño, Cristina; Dı́az-Cruz, José Manuel; Esteban, Miquel

doi:10.1002/elan.200603548

Cited by 5 publications

(2 citation statements)

References 36 publications

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“…When adsorption is present, Reverse Pulse Polarography (RPP) can be used [12], but it suffers from a lack of sensitivity. Then, ACP appears as a more convenient technique to avoid both problems, lack of sensitivity and adsorption influence, as it has been demonstrated recently in a study of the complexation of cadmium by humic acid [13]. However, a drawback of ACP is the choice of the more convenient phase angle, because the angle where I c becomes zero depends on the presence or absence of faradaic process and also on the instrument used.…”

Section: Introductionmentioning

confidence: 99%

“…In the previous work [13] the selection of the proper phase angle was through the visual observation of waves at different phase angle values, and the subsequent selection of the experimental angles which minimize the baseline (capacitive current close to zero) or the peak (faradaic current close to zero). However, this visual observation has some uncertainties due to the effects that faradaic processes have on capacitive current [1].…”

Section: Introductionmentioning

confidence: 99%

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Phase Sensitive Alternating Current Polarography: A Chemometric Approach for the Selection of Phase Angles

et al. 2006

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A method based on the combined use of multivariate curve resolution by alternating least squares (MCR-ALS) with phase sensitive alternating current polarography (ACP) is proposed to evaluate the phase angle where capacitive current is minimized in a much more accurate way than the visual inspection of ACP signals. The method allows, through the analysis of series of AC polarograms measured at different phase angles out the potential, to distinguish between faradaic and capacitive contributions. Then the angle at which the capacitive current is negligible can be shown and, in some cases, the influence of adsorption on measured currents minimized.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Phase Sensitive Alternating Current Polarography: A Chemometric Approach for the Selection of Phase Angles

et al. 2006

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Prometrine–Humic Acids Interactions Studied at a Water/1,2‐Dichloroethane Interface

2010

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The interaction of the herbicide prometrine (PROM) with humic acids (HA) in water was analyzed at a pH range between 2.00 to 10.00. For this purpose the transfer current of protons facilitated by PROM across a water/1,2-dichloroethane interface was employed to quantify PROM concentration in absence or in presence of HA. When humic acids were added in increasing amounts to the solution containing PROM, a gradual decrease in current values was observed, evidencing the retention of PROM by HA. This effect was more important at high pH values. From the results it is concluded that the adsorption of PROM is dependent on the pH and HA concentration. At high pH values the herbicide is strongly retained by HA, revealing a strong interaction probably due to the possibility of PROM (neutral species) to access to hydrophobic regions of AH, where van der Waals interactions prevail. The amount of PROM bounded to HA was calculated by subtracting peak current values in presence and in absence of HA and the adsorption isotherm was plotted. The concave or S type curves obtained, indicative of a process with high resistance to adsorption at low concentrations, was fitted with Freundlich isotherm.

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Alternating current anodic stripping voltammetry in the study of cadmium complexation by a reference Suwannee river fulvic acid: a model case with strong electrode adsorption and weak binding

et al. 2007

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The possibilities of anodic stripping voltammetry (ASV) using an alternating current (AC) scan in the stripping step have been checked through the study of the complexation of cadmium by Suwannee river fulvic acid (SRFA), a reference fulvic acid from the International Humic Substances Society. Because of the strong electrode adsorption of SRFA, AC mode appears to be a good approach to the study when proper selection of the phase angle is made. The goodness of AC mode in ASV has been demonstrated, and the complexation constant of 3.71 +/- 0.04 determined is in good agreement with the value of the constant obtained by the reference technique of reverse pulse polarography. Some particularities of SRFA have been observed, among them its homofunctional and strongly heterogeneous behaviour in cadmium complexation and the impossibility of avoiding electrode adsorption problems in ASV measurements at very low metal concentrations. Figure DP anodic stripping and AC anodic stripping voltammograms at -12 degrees and -65 degrees during the titration of a 10(-7) mol L(-1) Cd(II) solution with SRFA at pH 7.5 in 0.05 L(-1) Tris.

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Minimization of Electrode Adsorption Effects: The Cadmium–Humic Acid System Studied by Phase Sensitive Alternating Current Polarography

Cited by 5 publications

References 36 publications

Phase Sensitive Alternating Current Polarography: A Chemometric Approach for the Selection of Phase Angles

Phase Sensitive Alternating Current Polarography: A Chemometric Approach for the Selection of Phase Angles

Prometrine–Humic Acids Interactions Studied at a Water/1,2‐Dichloroethane Interface

Alternating current anodic stripping voltammetry in the study of cadmium complexation by a reference Suwannee river fulvic acid: a model case with strong electrode adsorption and weak binding

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