Browsing by Author "Nagles, Edgar"

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    Ex situ prepared nafion-coated antimony film electrode for adsorptive stripping voltammetry of model metal ions in the presence of pyrogallol red
    (2013) Arancibia, Veronica; Nagles, Edgar; Rojas, Carlos; Gomez, Marisol
    A nafion-coated antimony film electrode (NSbFE) was prepared ex situ and applied to the model metal ions Pb(II) and Cd(II) by adsorptive stripping voltammetry in the presence of pyrogallol red (PGR). To enhance the electroanalytical performance of the NSbFE, we optimized several operational parameters, including antimony concentration, deposition potential and time used in the preparation of the electrode, and effect of pH, ligand concentration (C-PGR), adsorptive potential, and time (E-ads, t(ads)). The NSbFE exhibited well developed signals for the reduction of the adsorbed complexes at -0.63 and -0.92 V for Pb-PGR and Cd-PGR, respectively, with higher current compared to unmodified electrodes. The optimum parameters for NSbFE preparation consisting of 100 mg L-1 Sb(III), 0.5 mol L-1 HCl at -1.5 V (150 s) and for the determination of Pb(II) and Cd(II) were pH = 4.5 (acetate buffer); C-PGR = 2.8 mu mol L-1; E-ads = -0.40 V and t(ads) = 100 s. The electrode presents good linear behavior in the examined concentration range from 0.9 to 12.0 mu g L-1 for both metal ions, with a limit of detection (3 sigma) of 0.4 and 0.9 mu g L-1 for Pb(II) and 0.5 and 1.0 mu g L-1 for Cd(II) using 2-mm and 3-mm diameter glassy carbon electrodes, respectively. The relative standard deviation for a Pb(II) a Cd(II) solution (9.8 mu g L-1) was 2.0% for six successive assays. The method was validated using certified reference water for trace elements (TMDA-61) with satisfactory results. Finally, the method was applied to the determination of Pb(II) and Cd(II) in tap and mineral water. (C) 2013 Elsevier B.V. All rights reserved.
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    Nafion-mercury coated film electrode for the adsorptive stripping voltammetric determination of lead and cadmium in the presence of pyrogallol red
    (2012) Nagles, Edgar; Arancibia, Veronica; Rojas, Carlos; Segura, Rodrigo
    An adsorptive stripping voltammetric (AdSV) method is presented for the simultaneous determination of Pb(II) and Cd(II) at trace levels in natural waters, based on metal complexation with pyrogallol red (PR) and subsequent adsorptive deposition on a Nation-mercury coated glassy carbon electrode (NHgFE). Pyrogallol red forms complexes with a metal:ligand stoichiometry of 1:1 with Pb(II) and of 1:2 with Cd(II). Optimal analytical conditions were pH 4.0 (acetate buffer); C-PR = 2.8 mu mol L-1; E-ads = -0.40 V vs. Ag/AgCl; t(ads) = 100 s. The linear calibration curves ranged from 1.0 mu g L-1 to 16.0 mu g L-1 for Pb(II) and from 1.0 mu g L-1 to 13.0 mg L-1 for Cd(II). The detection limits (S/N=3) were 0.05 mu g L-1 for Pb(II) and 0.01 mg L-1 for Cd(II). The relative standard deviation was 1.0% and 2.0% (n = 7), respectively, for a solution containing 5.0 mu g L-1 Pb(II) and Cd(II). The method was validated by determining Pb(II) and Cd(II) in certified reference waste water (SPS-WW1). Finally, the method was applied to the determination of Pb(II) and Cd(II) in commercial mineral water samples after UV digestion. (C) 2012 Elsevier B.V. All rights reserved.
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    Simultaneous Determination of Antimony(III) and Molybdenum(VI) by Adsorptive Stripping Voltammetry Using Quercetin as Complexing Agent
    (2013) Rojas, Carlos; Arancibia, Veronica; Gomez, Marisol; Nagles, Edgar
    A sensitive and selective voltammetric method for simultaneous determination of Sb(III) and Mo(VI) using Quercetin (Q) as complexing agent is described. Optimal conditions were found to be: pH3.7, CQ=6.0 mu molL1 and Eacc=0.10V. The LOD (3 sigma) for Sb(III) are 0.076 and 0.040 mu gL1, whereas for Mo(VI) are 0.086 and 0.048 mu gL1 with tacc of 60 and 120s, respectively. The method was validated using synthetic sea water (ASTM D665) and was applied to the determination of Sb(III) and Mo(VI) in natural waters with satisfactory results.