Abstract

The detection of gallic acid (GA) and uric acid (UA) is desirable due to their important role in various biological functions. However, their simultaneous detection is still challenging due to the mutual interference with similar oxidation potentials. Electro-grafted polymers on carbon electrode surfaces with desirable composition and structure can induce excellent selectivity towards their electrochemical detection. Herein, the present study aims at developing the electro-grafting of poly-3,5-diamino-1,2,4-triazole (DAT) on glassy carbon (GC) electrodes by controlled electro-polymerization. The presence of nitrogen-rich hydrazo bonds (–NH) in triazole can establish strong intramolecular interactions (N-H) with free- OH (gallic acid) and quinone (uric acid) groups, which facilitate good selectivity at high mass transfer rates. This phenomenon was experimentally examined using differential pulse voltammetry thus revealing a significant separation of potentials of about 110 mV, with peak potentials of E = 0.16 and 0.27 V for gallic and uric acid, respectively. Using electropolymerized triazole (p-DAT/GC) as a modified electrode, the sensing response for gallic and uric acid was found to be linear within a concentration range from 10 to 128 µM with a limit of detection (LOD) of about 2.8 and 1.5 µM. The p-DAT/GC electrode exhibited a good recovery range when used for realistic detection in human urine samples. Therefore, this work is a valuable toolkit for the detection of gallic and uric acid thus paving the way for a wide range of opportunities regarding real-time detection in electrochemical sensing applications.