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A novel approach of using a gold disc microelectrode to analyze sweat samples for copper ions by anodic square wave stripping voltammetry (SW stripping voltammetry) is described. Sweat was collected from the lower back of four subjects after physical exercise and the sample volume required for the determinations was 100 μL. Under the optimized conditions, the calibration plot was linear over the range 1-100 μmol L(-1) Cu(II) with a limit of detection of 0.25 μmol L(-1). The precision was evaluated by carrying out five replicate measurements in a 1 μmol L(-1) Cu(II) solution and the standard deviation was found to be 1.5%. Measurements were performed by inserting the microelectrode into sweat drops and Cu(II) concentrations in the analyzed samples ranged from 0.9 to 28 μmol L(-1). Values obtained by the proposed voltammetric method agreed well with those found using graphite furnace atomic absorption spectroscopy (GFAAS)., (Copyright © 2010 Elsevier B.V. All rights reserved.)

Abstract: The cathodic reduction of nitrate at copper electrodes was investigated by using scanning electrochemical microscopy (SECM) in the stripping-mode SECM (SM-SECM). This electrochemical process is facilitated at surfaces activated by a potential protocol involving anodic dissolution and subsequent reduction of copper cations, which causes an increase in the surface area. In the presence of chloride, a much more significant current enhancement was noticed, and a mechanism based on the formation of CuCl was proposed to explain the increased rate of nitrate reduction at this experimental condition. [Copyright &y& Elsevier]

Abstract: A novel approach of using a gold disc microelectrode to analyze sweat samples for copper ions by anodic square wave stripping voltammetry (SW stripping voltammetry) is described. Sweat was collected from the lower back of four subjects after physical exercise and the sample volume required for the determinations was 100μL. Under the optimized conditions, the calibration plot was linear over the range 1–100μmolL−1 Cu(II) with a limit of detection of 0.25μmolL−1. The precision was evaluated by carrying out five replicate measurements in a 1μmolL−1 Cu(II) solution and the standard deviation was found to be 1.5%. Measurements were performed by inserting the microelectrode into sweat drops and Cu(II) concentrations in the analyzed samples ranged from 0.9 to 28μmolL−1. Values obtained by the proposed voltammetric method agreed well with those found using graphite furnace atomic absorption spectroscopy (GFAAS). [ABSTRACT FROM AUTHOR]

Direct electrochemical generation of hydrogen peroxide in aqueous medium represents an attractive method for the production of the oxidizing agent. This paper describes the development of electrocatalysts comprising Printex L6 carbon black containing 0 to 10% (w/w) of copper or cobalt phthalocyanine (CuPc and CoPc, respectively) as modifier. Formation of H 2 O 2 by the ORR in acidic medium was investigated by linear voltammetry using a rotating ring-disc electrode, whose glassy carbon disc contained a microporous layer of the catalyst. Incorporation of CuPc into Printex decreased the current efficiency for H 2 O 2 formation [i(H 2 O 2 )%] from 75.4% for unmodified Printex to a minimum of 53.3% when 10% of the modifier was present. However, i(H 2 O 2 )% increased when CoPc was employed as modifier, and a maximum value of 92.3% was attained with Printex containing 1.0% CoPc. Moreover, a shift of +340 mV (relative to unmodified Printex) was observed in the overpotential required for the generation of H 2 O 2 when 10% of CoPc was present. SECM demonstrated that, at a potential of -0.2 V, Printex with 10% CoPc produced larger amounts of H 2 O 2 compared with unmodified Printex. It is concluded that the use of the CoPc modifier is promising for the electrogeneration of H 2 O 2 on a large scale. [ABSTRACT FROM AUTHOR]