Adsorptive Catalytic Voltammetry of Physcion in the Presence of Dissolved Oxygen at a Carbon Paste Electrode |
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Authors: | Yonglan?Ding Email author" target="_blank">Junan?LiEmail author Junjie?Fei |
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Institution: | (1) College of Chemistry, Xiangtan University, 411105 Xiangtan, Hunan, P.R. China |
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Abstract: | A novel electroanalytical method for the determination of physcion is described for the first time. Physcion yields an adsorption catalytic voltammetric peak at –0.74V (vs. SCE) in 0.4molL–1 NH4Cl–NH3·H2O buffer solution (pH 10.5) at a carbon paste electrode (CPE). The experimental results indicated that physcion is efficiently accumulated at a CPE by adsorption. In the subsequent potential scan, physcion was reduced to a homologous anthrahydroquinone compound. The compound was then immediately oxidized to physcion by the dissolved oxygen in the solution, and then physcion was again reduced at the CPE. As a result, a cyclic catalytic reaction was established. The second-order derivative peak current is proportional to the physcion concentration in the ranges of 2.0×10–104.0×10–9molL–1 (accumulation 90s) and 4.0×10–92.0×10–8molL–1 (accumulation 60s). The limit of detection is 8×10–11molL–1 (S/N=3) for a 120s accumulation time. The method was applied to the direct determination of physcion in the medicinal plant polygonum multiflorum Thumb with satisfactory results. |
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Keywords: | : Physcion carbon paste electrode adsorptive catalytic voltammetry |
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