Amperometric determination of uric acid, creatinine and cholesterol on planar electrodes modified by gold particles in the flow-injection system

Abstract

© 2019 Ural Federal University. All rights reserved. A method of amperometric determination of uric acid (UA), creatinine (Cr) and cholesterol (CHO) on planar carbon electrodes (PE) modified by gold particles in a flow-injection system has been developed. PE with immobilized gold particles (Au-PE) is catalytically active with respect to UA, Cr and CHO. A multiple current increase at modifier oxidation potentials and an oxidation potential decrease of the organic compound as compared to the unmodified electrode during their electrooxidation on Au-PE was observed. The effect of the electrochemical and hydrodynamic parameters of the flow-injection system on the analytical signal was estimated for each compound. The working conditions (applied potential and flow rate) for the maximum analytical signal registration at the modified electrode for the studied biologically active compounds (BAC) were selected. With the joint presence of the considered BAC, the dependence graphs of the current on the analyte concentration in logarithmic units were linear in the range from 510-9 to 510-3 mol/l for UA, from 510-7 to 5 0-3 mol/l for Cr and from 510-8 to 510-3 mol/l for CHO. Using the two-detector flow system and double planar electrodes (DPE) modified with gold particles (Au-DPE) allowed the simultaneous determination of the considered BAC. The proposed method was used to determine UA, Cr and CHO in the urine.