Electrochemical detection of uric acid and ascorbic acid using r-GO/NPs based sensors

A sensitive and selective electrochemical sensor, based on reduced graphene oxide and gold nanoparticles obtained by simple co-electrodeposition, was developed for the detection of uric acid and ascorbic acid. Because of the electrochemical oxidation of both uric and ascorbic acid depending on the pH, the sensor performances were studied at different pH values. Excellent results were obtained for uric acid detection in a linear range from 10 to 500 µmol dm⁻³ with a sensitivity of 0.31 µA cm⁻² µM⁻¹. A limit of detection and quantification of 3.6 µM and 10.95 µmol dm⁻³, respectively, was calculated. Sensors showed good selectivity toward different interfering species present in the matrix of milk, fruit juice and urine (Na⁺, NH₄⁺, Cl⁻ and glucose). A simultaneous detection of uric acid and ascorbic acid was also carried out reaching a limit of detection of 2.26 and 5.63 µmol dm⁻³, respectively. Sensors were also validated measuring both acids in real samples of foods and body fluids (commercial milk and fruit juice and urine). Excellent results were achieved in good agreement with conventional techniques.