A Gold Nanoparticles-Modified Carbon Paste Electrode for Uric Acid Determination in Human Urine without Pretreatment Steps

Uric acid (UA) is a water soluble compound which is produced from purine metabolism in human body. High or low levels of UA are symptoms of some deficiencies in human body, so finding a simple and sensitive method for determination of UA is important. A new chemically modified electrode was fabricated by gold nanoparticles (GNPs) and carbon paste electrode (CPE) for determination of UA in human urine. Gold nanoparticles-modified carbon paste electrode (GNPs/CPE) was characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Some important experimental parameters such as amount of modifier, pH and scan rate (?) effects were studied by cyclic voltammetry and the best values for analysis were chosen. To propose a mechanism for oxidation of UA on the surface of modified electrode, the number of involved electrons and protons and diffusion coefficient of UA (DUA) was calculated. Square wave voltammetry (SWV) was used as an accurate technique for quantitative measurements. A good linear relation was observed between anodic peak current (ipa) and UA concentration (CUA) in the range of 2×10–7 to 2×10–4 mol L–1, and the detection limit (DL) was obtained to be 3.9×10–8 mol L–1, that is comparable to recent studies. This paper demonstrates a novel, simple, selective and rapid sensor for determination of UA in the analytical real samples.