Determination of uric acid in human urine by eliminating ascorbic acid interference on copper(II)-polydopamine immobilized electrode surface

• A simple strategy for preparation of ploydopamine-Cu(II) coating on electrode.
• The sensor shows the extraordinary selectivity for electrochemical determination of UA.
• Modified electrode was characterized in detail.
• Practical application was demonstrated in urine samples.

The polydopamine (PD) coating was spontaneously formed through simple immersion of glassy carbon (GC) electrode in a dilute aqueous solution of dopamine (DA) at acidic solution (pH = 4.5) in the presence of Cu2+. Copper(II) ions were anchored on surface of GC electrode to prepare a PD-Cu(II) modified electrode. The morphology, composition and electrochemical properties of the PD-Cu(II) films were characterized by scanning electron microscopy, energy-dispersive spectrometry, X-ray photoelectron spectroscopy, powder X-ray diffraction, electrochemical impedance spectroscopy and cyclic voltammetry. This modified electrode shows the extraordinary selectivity for electrochemical determination of uric acid (UA) without interference of high concentration of ascorbic acid (AA). Under coexistence of 5 mM AA, the differential pulse voltammetry peak current of UA give linear response over the range of 0.06–1.68 mM (R2= 0.9934) with detection limit of 24.6 μM (S/N = 3). Furthermore, the proposed sensor is ideal for the analysis of UA in human urine samples providing satisfactory results.

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