Electrochemical sensor for simultaneous detection of dopamine and uric acid based on a carbon paste electrode modified with nanostructured Cu-based metal-organic frameworks

In this work, nanostructured Cu-BTC (Cu-benzene-1,3,5-tricarboxylic acid) metal organic framework (MOF) was synthesized by ultrasonic assisted hydrothermal technique. Energy-dispersive X-ray spectroscopy (EDS), fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) analysis, field emission-scanning electron microscopy (FE-SEM), as well as elemental mapping image have been employed for characterizing morphology, composition and structure of Cu-BTC MOF. Then, a simple and sensitive electrochemical sensor (Cu-BTC MOF modified carbon paste electrode (CPE)) has been fabricated and used for detection of dopamine. In addition, analytical function of electrochemical sensor has been evaluated by cyclic voltammetry (CV), differential pulse voltammetry (DPV), and chronoamperometry (CHA). Based on the optimized condition, Cu-BTC/CPE exhibited the linear dynamic ranging between 0.05 and 500.0 μM with a limit of detection (LOD) 0.03 μM to determine dopamine and 0.5–600.0 μM for uric acid with limit of detection of 0.2 μM. Also, we assessed the as-prepared electrode by simultaneously detecting dopamine and uric acid. In the course of the electro-oxidation process of the analytes, two separate peaks were observed on the modified electrode. In addition, test in the real samples (dopamine injection and urine) has been investigated for which acceptable recoveries were obtained. This method provides a simplified and sensitive method to detect dopamine and uric acid.