Sensitive and Fast Simultaneous Voltammetric Determination of Dopamine and Uric Acid Using Simple Screen-Printed Carbon Electrode Without Pretreatment and Modification

A simple, commercially available, unmodified screen-printed carbon electrode (SPCE) was investigated for the simultaneous voltammetric determination of dopamine (D/A) and uric acid (U/A) in a medium of very low concentration of supporting electrolyte for the first time. The ordinary, simple SPCE from DropSens (DS-SPCE) was found to be able to separate the overlapping peaks of D/A and U/A with a wide peak potential separation of 300 mV in a medium of very low concentration (0.001 M) of NaH₂PO₄ as supporting electrolyte (buffer of low capacity) at pH 8.0. Medium of low concentration of electrolyte made it possible to expose the bare electrode surface for its high catalytic activity which resulted into a high peak current signals, particularly for D/A. The DS-SPCE showed excellent electrocatalytic performance than the other SPCE. The effect of electrolyte concentration and pH on the electrocatalytic behavior of electrode were thoroughly discussed. The DS-SPCE displayed a sensitive results in good linear ranges from 0.1–5 to 6–20 µM for D/A and 0.5–41.5 µM for U/A. The disposable electrode demonstrated better discrimination ability toward the detection of D/A and U/A over ascorbic acid and other potential interfering species. Moreover, the sensor presented sensitive and highly accurate results in human urine samples without preliminary treatment. The DS-SPCE sensor was found to be simple, efficient, fast, low cost, and greener than the other reported modified sensors, while providing better sensitivities to detect D/A and U/A simultaneously. Thus, the bare, unmodified DS-SPCE can be a convenient sensing device for the routine analysis of D/A and U/A, without requiring any complex pretreatment and modification steps of the electrode.