▎ 摘　　要

In this paper, an electrochemical technique is introduced for the determination of streptomycin (STR) in the presence of oxytetracycline (OTC) in milk samples. A novel bifunctional modified screen-printed electrode (SPE) modified with oracet blue, silver nanoparticles, and graphene oxide (OB/SNPs/GO/SPE) was fabricated. The modified electrode plays a catalyzer role for electrooxidation of STR at pH = 7.0 and reveals a facile a separation between the oxidation peaks of STR and OTC. Calculation of kinetic parameters such as the electron transfer coefficient alpha and the heterogeneous rate constant k ' of STR at the OB/SNPs/GO/SPE as 8.1 +/- 0.07 cm s(-1) and 0.32 have been obtained based on the theoretical model of Andrieux and Saveant. A differential pulse voltammetric measurement demonstrates two linear dynamic ranges, 0.4 to 240.0 nM and 240.0 to 720.0 nM and a detection limit of 0.17 nM for STR. The sensitivities of the OB/SNPs/GO/SPE towards the oxidation of STR in the absence and presence of OTC were 2.625 x 10(-1) and 2.633 x 10(-1) mu A/mu M, respectively.