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The citric acid modified glassy carbon electrode (CA/GC) was constructed by potentiostatic technique and used for simultaneous determinations of ascorbic acid (AA), dopamine (DA) and uric acid (UA) by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The CA/GC electrode exhibits excellent electrocatalytic activity towards AA, DA and UA. The oxidation peaks are well separated with the potential differences between AA and DA, DA and UA, and AA and UA being 170, 130 and 300 mV, respectively, which is large enough to determine AA, DA and UA simultaneously. The catalytic peak currents obtained were linearly dependent on the concentrations of AA, DA and UA in the range of 2.0×10-6~1.5×10-3 mol?L-1, 6.0×10-7~1.0×10-3 mol?L-1, and 6.0×10-7~1.0×10-3 mol?L-1, respectively. The proposed sensor shows good reproducibility and may be applied practically in the determinations of AA, DA and UA.

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ascorbic acid, dopamine, uric acid, citric acid, modified electrode

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