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La(OH)3 nanoparticles were successfully prepared with the sol-gel method, and the preparation of a glassy carbon electrode modified by La(OH)3 nanoparticles was investigated. The modified electrode shows an excellent electrocatalytic activity for hydroquinone. The anodic and cathodic overpotentials are reduced by ca. 143 mV and 83 mV, respectively, compared with those obtained with a bare glassy carbon electrode. According to the electrochemistry response, we set up a new method to determinate hydroquinone. The catalytic anodic current response of differential pulse voltammogram increases linearly with hydroquinone concentrations from 2.7×10-7 to 6.5×10-4 mol L-1 with a detection limit of 6.0×10-8 mol L-1. The recovery of hydroquinone in a simulative sample is satisfactory, especially for its elimination of the interference of 1,2-benzenediol (pyrocatechol) and 1,3-benzenediol (m-dihydroxybenzene). The method is simple, quick, and sensitive. [ABSTRACT FROM AUTHOR]

Abstract: A glassy carbon electrode modified with CeO2 nanoparticles was constructed and was characterized by electrochemical impedance spectrum (EIS) and cyclic voltammetry (CV). The resulting CeO2 nanoparticles modified glassy carbon electrode (CeO2 NP/GC electrode) was used to detect uric acid (UA) and ascorbic acid (AA) simultaneously in mixture. This modified electrode exhibits potent and persistent electron-mediating behavior followed by well-separated oxidation peaks towards UA and AA with activation overpotential. For UA and AA in mixture, one can well separate from the other with a potential difference of 273mV, which was large enough to allow the determination of one in presence of the other. The DPV peak currents obtained in mixture increased linearly on the UA and AA in the range of 5.0×10−6 to 1.0×10−3 mol/L and 1.0×10−6 to 5.0×10−4 mol/L, with the detection limit (signal-to-noise ratio was 3) for UA and AA were 2.0×10−7 and 5.0×10−6 mol/L, respectively. The proposed method showed excellent selectivity and stability, and the determination of UA and AA simultaneously in serum was satisfactory. [Copyright &y& Elsevier]