Simultaneous voltammetric determination of dopamine and uric acid using screen printed carbon electrode modified with quercetin functionalized-iron oxide nanoparticles

Due to close oxidation potential values of dopamine (Dop) and uric acid (Uric), their simultaneous electrochemical detection in biological fliuds has always been a great problem of contineous research work. To address this issue magnetic iron oxide (Fe3O4) nanoparticles are promising eletrode materials owing to their high catalytic activity, easy synthesis procedure, lower cost and non toxic nature. Therefore, in the present work, we have investigated, a novel electrochemical sensor which is based on a screen printed carbon electrode (SPCE) modified with quercetin (Qr) functionalized-iron oxide nanoparticles (Qr-Fe3O4/SPCE) for the simultaneous voltammetric detection of Dop and Uric. The SEM analysis confirmed the porous morphology with nanosize distribution and XRD revealed the cystalline strucutre. The average size of the bare Fe3O4 and Qr-Fe3O4 nanoparticles were estimated to be 11.7 and 9.1 nm, respectively. The FT-IR analysis confirmed the successful functionalization of quercetin on the surface Fe3O4 nanoparticles. The cyclic voltammetric and electrochemical impedance spectroscopic techniques were used to characterize the electrical properties of the electrodes. The Qr-Fe3O4 sensor greatly improved the peak current signals towards the oxidation of Dop and Uric which was found to be due to the synergistic electrocatalytic effect of Qr and Fe3O4 nanoparticles on the electrode surface. The fabricated sensor presented linear peak current responses as a funtion of Dop and Uric concentrations in the ranges from 0.2 – 50 µM and 0.2 – 25 µM, with detection limits of 0.07 and 0.08 µM, respectively. Moreover, the Qr-Fe2O3/SPCE based sensor showed good repeatability with RSD of 1.7% for Dop and 2.8% for Uric and displayed good discrimination ability over the common interferents. The successful application of the sensor to the spike urine samples enabled the determinations with good recoveries without matrix effect from urine sample. Thus the developed electrochemical sensor could be a suitable sensing device for Dop and Uric with a large peak potential separation ability due to its easy preparation procedure, ecofriendly nature, lower cost and good sensitivity and selectivity.