A chemically modified carbon paste electrode (CPE) based on SnO2/α-Fe2O3 hierarchical nanorods (SFOHNRs) were constructed as a novel simple electrochemical sensor for a sensitive simultaneous determination of dopamine (DA) and tramadol (TRA). To investigate electrochemical behaviors of DA and TRA several techniques such as differential pulse voltammetry (DPV), cyclic voltammetry (CV) and chronoamperometry (CA) methods were used. SFOHNRs were fabricated via three step process. In order to characterize SFOHNRs several techniques such as field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) technique and energy dispersive X-ray spectroscopy (EDX) were used. Application of SFOHNRs as the modifier of the CPE (SFOHNRs/CPE) showed high oxidation peak currents for determination of DA and TRA due to its catalytic effect and its high surface area. Using DPV technique, the sensor showed linear ranges of 0.1-70 µM and 0.5-65 µM and low detection limits of 40 nM and 65 nM toward DA and TRA, respectively. The fabricated sensor exposed excellent sensitivity, simplicity and high selectivity toward simultaneous determination of DA and TRA. The analytical performance of the sensor has been evaluated for analysis of DA and TRA in human blood serum and urine with satisfactory results.
