Simultaneous Voltammetry Detection of Dopamine and Uric Acid in Pharmaceutical Products and Urine Samples Using Ferrocene Carboxylic Acid Primed Nanoclay Modified Glassy Carbon Electrode

A sensitive and selective voltammetric sensing method has been developed for simultaneous determination of dopamine (DA) and uric acid (UA) using ferrocene carboxylic acid modified halloysite nanotubes (Fc/HNT) on the surface of glassy carbon electrode (GCE). It was found that beneath optimum experimental condition, the electrocatalytic oxidation of DA and UA occurred at +0.08 V and +0.22 V at Fc/HNT/GCE. These oxidation peak potentials are less positive and ensuing peak current values are almost thrice than unmodified GCE. A well-resolved peak potential window (∼150 mV) for oxidation of DA and UA were observed in the modified electrode system. Differential pulse voltammetry (DPV) method was employed for electrochemical detection of DA and UA using Fc/HNT/GCE at trace level. The calibration curves for DA and UA were obtained within the dynamic linear range of 6.0 × 10 −7 to 60 × 10 −5 M (R 2 = 0.9959) and 1.3 × 10 −6 to 100 × 10 −5 M (R 2 = 0.9925), respectively with the detection limits of 0.02 and 0.03 μM by using DPV method. An enhanced stability with good reproducibility was obtained from amperometry studies under hydrodynamic condition. The amperometric method was applied for detection of DA and UA present in pharmaceutical products and urine samples.