Abstract
Electrochemical detection of Se4+has been performed by anodic stripping voltammetry on a boron-doped diamond (BDD) electrode modified with gold nanoparticles deposited through chronocoulometry. This method is based on the affinity between the gold nanoparticles and Se0, while the BDD electrode is presented as an ideal material for metal modification due to its unique properties. The resulting anodic stripping voltammograms exhibited a clear peak at 0.9 V versus AgCl related to Se4+, and highly accurate (r2=0.99) calibration curves could be obtained for a selenium concentration range between 10 and 100 μg/L. The influence of Se deposition time and other metals dissolved in solution (Cu, Cd, Pb, Cr, and B) has been investigated as well, and it was found that the Se4+calibration curves remained unaltered. For all the experiments performed, a detection limit around 10 μg/L was achieved. The high accuracy and reproducibility of the results as well as the excellent stability of the electrode material proves the excellent capabilities of this system for selenium detection.
Highlights
Selenium is an essential micronutrient for animals and humans but can be extremely toxic if absorbed in large doses [1]
A deposition potential of −0.4 V has been applied during 2 minutes for Se deposition because the Se4+ reduction peak was observed around that potential on gold-modified boron-doped diamond (BDD) electrodes
Anodic stripping voltammetry measurements were carried out using the aforementioned mixture and under the same conditions as those presented on Figure 1, that is, the BDD electrode was modified through chronocoulometry at −35 mC cm−2 for 1 min in a solution of HAuCl4 100 mg/L in 0.1 M hydrogen chloride (HCl)
Summary
Selenium is an essential micronutrient for animals and humans but can be extremely toxic if absorbed in large doses (over 400 μg per day) [1]. Many techniques have been developed in order to analyze Se4+ concentrations at the μg/L level but the most common method is stripping voltammetry due to its simplicity, rapidity, and excellent sensitivity Both cathodic stripping voltammetry using a hanging mercury drop electrode [5,6,7,8,9,10,11] and anodic stripping voltammetry (ASV) using gold (rotating disk or film) electrodes [12,13,14] have been extensively studied for Se4+ determination in acidic solutions. BDD has been selected for gold deposition due to its outstanding properties compared to other conventional electrode materials such as a wide electrochemical potential window, low background current, and weak adsorption of polar molecules [16, 17] These properties offer a significant advantage for metal modification as it was already shown for the detection of As3+ and As5+ mixtures [18]. The selective detection of Se4+ in the presence of interference metal ions was studied
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