Electrochemical sensor for the determination of thiourea using a glassy carbon electrode modified with a self-assembled monolayer of an oxadiazole derivative and with silver nanoparticles

This article reports on an electrochemical sensor for thiourea. It is based on a glassy carbon electrode (GCE) modified with a self-assembled monolayer of an oxadiazole derivative and with silver nanoparticles. The modified GCE demonstrated highly catalytic activity in terms of thiourea oxidation. The peak potential is shifted to negative values compared to a GCE coated with silver nanoparticles only. The electrode was characterized by linear sweep voltametry, cyclic voltammetry and chronoamperometry, and thiourea was determined by differential pulse voltammetry in aqueous buffer of pH 7.0 resulting in two linear response ranges of 0.001 − 69.4 and 69.4 − 833.3 μM and the limit of detection of 0.1 nM. The method was applied to the determination of thiourea in copper refinery electrolyte, orange juice and tap water samples. The recoveries ranged from 96.9 to 108.0 %. Graphical Abstract A glassy carbon electrode was modified with silver nanoparticles (SNP−GCE) using continuous cyclic potential in solution of nitric acid and AgNO 3 . Oxadiazole - modified SNP−GCE (OSNP−GCE) was prepared by the self-assembling technique directly onto the SNP−GCE.