Electrochemical sensors for simultaneous detection of dopamine and uric acid based on a composite of electrochemically reduced graphene oxide and PEDOT:PSS-modified glassy carbon electrode

Herein, we report the development of a successful electrochemical sensor based on a composite of electrochemically reduced graphene oxide (ErGO) and poly(3,4-ethylenedioxythiophene):poly(styrene-4-sulphonate) (PEDOT:PSS) for the simultaneous detection of dopamine (DA) and uric acid (UA). A glassy carbon electrode was modified with a composite of ErGO and PEDOT:PSS and further characterized using Raman spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), and electrochemical impedance spectroscopy. The obtained composition of weight ratio between ErGO and PEDOT:PSS as 7:3 demonstrated the highest electrocatalytic activity for the simultaneous detection of DA and UA when it was investigated using differential pulse voltammetry technique under optimized experimental conditions. The developed sensor also exhibited two separate well-defined anodic peaks of both analytes with a linear response over the concentration range of 3-33 & mu;M for DA and 10-110 & mu;M for UA. The limits of detection for DA and UA were 0.4 and 0.5 & mu;M, respectively. The proposed sensor also displayed good stability and reproducibility for the simultaneous detection of DA and UA for five consecutive days of measurements. In addition, the developed sensor exhibited a good selectivity for the simultaneous detection of DA and UA against several potential interferences, such as K+, Cl-, C2O42, PO43 � , ascorbic acid, glucose, and urea, with % recovery values of 97%-101% for DA and 97%-103% for UA, which are acceptable in the analytical range. Furthermore, this sensor was successfully used in detecting DA and UA in real human samples using standard addition techniques and thus may have a potency to be further employed in practical applications.