▎ 摘　　要

A bare glassy carbon electrode (GCE) was reformed by carboxylated graphene oxide/lanthanum, and the modified electrode, called GO-COOLa/GCE, was fabricated for simultaneously detecting dopamine (DA), uric acid (UA) and nitrite (NO2-) by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and amperometry. Several factors which affected the electrocatalytic activity of the GO-COOLa/GCE electrode, such as the effect of pH, scan rate and concentration were studied. Due to the combination of carboxylated graphene oxide and lanthanum ions, the GO-COOLa/GCE sensor showed rapid response, excellent selectivity and high catalytic performance toward the electrooxidation of DA, UA and NO2-. In optimized conditions, two linear response ranges for determining DA were obtained over ranges of 0.01-1.96 x 10(2) mu M and 1.96 x 10(2)-1.23 x 10(3) mu M with detection limit of 0.018 mu M (S/N = 3). And the responses of the GO-COOLa/GCE electrode for UA and NO2- were linear in the region of 1-1.53 x 10(3) mu M and 1-2.75 x 10(3) mu M with detection limits of 0.058 mu M and 0.070 mu M, respectively. Furthermore, this reformed electrode was successfully used to the detection of DA, UA and NO2- in real urine and serum samples, showing its promising application in the electroanalysis of real samples. (C) 2015 Elsevier Ltd. All rights reserved.