A novel electrochemical sensor based on Fe-doped MgNi2O3 nanoparticles for simultaneous determination of dopamine, uric acid, nicotine and caffeine over very wide linear ranges

In this study, we have synthesized MgNi2O3 and Fe-doped MgNi2O3 by sol-gel method and characterized the products by powder X-ray diffraction, UV-visible spectroscopy, vibrating sample magnetometer, X-ray photoelectron spectroscopy, scanning and transmission electron microscopy for confirmation of morphology, optical, structural, and magnetic properties. An electrochemical sensor based on 2.5 wt% Fe doped MgNi2O3 nanoparticles modified glassy carbon electrode (GCE) has been fabricated and used for simultaneous electrochemical sensing of Dopamine (DA), Uric Acid (UA), Nicotine (NIC), and Caffeine (CA) for the first time. The MgNi1.95Fe0.05O3 modified GCE shows four strong well-defined separate oxidation peaks of DA, UA, NIC and CA in their mixture in both cyclic and square wave voltammetry studies in phosphate buffer saline (pH 7). Under optimized experimental conditions, oxidation currents increased linearly with the increase in concentration over very wide ranges of 0.1-1000, 0.1-5000, 50-6000, and 50-4000 mu M for DA, UA, NIC and CA and the corresponding lowest detection limits (LODs) were calculated as 0.017, 0.104, 0.098 and 0.276 mu M (S/N = 3) respectively. These measurable concentration ranges and LODs are much higher than the values ever reported in the literature for the sensor made of a simple stable electrode material Fe-MgNi2O3 without requiring adhesives, enzymes or modifiers.