▎ 摘　　要

Determination of levodopa and tyrosine as two important species for treatment of Parkinson's disease is described. A novel electrochemical sensor involving graphene oxide/ZnO nanorods (GR/ZnO) nano composite and the graphite screen-printed electrodes (GSPE) was developed for the simultaneous detection of levodopa and tyrosine. The screen-printed electrodes with several advantages, including low cost, versatility and miniaturization were employed. On the other hand, the graphene oxide/ZnO nanorods nano composite was casted on the surface of GSPE to obtain GR/ZnO/SPE. The proposed nano sensor has excellent performance such as high sensitivity, good selectivity and analytical application in real samples. The combination of graphene oxide/ZnO nanorods nano composite with the screen-printed electrode is favorable for amplifying electrochemical signals. Under optimized conditions square wave voltammetry (SWV) exhibited linear dynamic ranges from 1.0 X 10(-6) to 1.0 X 10(-3) M and 1.0 X 10(-6) to 8.0 X 10(-4) M with detection limits of 4.5 X 10(-7) M and 3.4 X 10(-7) M for levodopa and tyrosine respectively.