An L-tyrosine (L-Tyr) covalently functionalized graphene oxide (GO) composite (Tyr-GO) has been prepared through amide bonds, which is further used to modify glassy carbon electrode (GCE) by simple dipping-drying method. The differential pulse voltammetry (DPV) peaks of dopamine (DA) and ascorbic acid (M) can be completely separated with a peak potential difference of 414 mV by using the fabricated Tyr-GO/GCE, holding promise for simultaneous determination of DA and AA. The peak currents are linearly with the concentration of DA in the range from 1.0 x 10(-6) to 5.0 x 10(-4) mol/L with a detection limit of 2.8 x 10(-7) mol/L. In addition, the modified electrode exhibits excellent reproducibility and stability. (C) 2014 Elsevier B.V. All rights reserved.