Cysteamine Capped Silver Nanoparticles and Single-walled Carbon Nanotubes Composite Coated on Glassy Carbon Electrode for Simultaneous Analysis of Hydroquinone and Catechol

A stable complex of silver nanoparticles (Ag NPs) capped by cysteamine (Cst) together with single-walled carbon nanotube (CNTs) was used to modify a glassy carbon electrode (GCE) for simultaneous detection of hydroquinone (HQ) and catechol (CT). The resulting electrode (AgCst-CNTs/GCE) showed excellent electrocatalysis and reversibility towards this electroactive pair. The peak separations of their oxidation-reduction peaks decreased significantly, compared with those of the unmodified GCE. The signal responses of the AgCst-CNTs/GCE were 5-fold higher while its peak potential separation remained unchanged (ca. 130 mV), compared to the CNTs-modified GCE. The oxidation peak currents obtained for HQ and CT exhibited linearly from submicromolar to hundred micromolar concentrations without any cross-interference. The modified electrode possessed a very large active surface area with a detection limit (S/N=3) of 10 and 40 nM for HQ and CT, respectively. The sensor was demonstrated for the analysis of river water and topical cream as evinced by high accuracy and reproducibility.