Graphene-Modified Electrode for Linear Sweep Voltammetric Sensing of Catechol

A graphene sample (EGr) was obtained in a single-step synthesis by electrochemical exfoliation of graphite rods. A combination of 0.05 M ammonium sulfate and 0.05 M ammonium thiocyanate was employed, leading to a graphene sample composed of few-layer, multi-layer and graphene oxide flakes. Due to the mild exfoliation conditions, large sheets with linear sizes in the range of tens to hundreds of micrometers were produced. The LSV technique gave information about the effect of catechol concentration on the electrochemical signal of bare and graphene-modified electrodes. Based on the resulting calibration plots, the corresponding analytical parameters (linear range, sensitivity, limit of quantification and limit of detection) were calculated for each electrode. In the case of the EGr/GC electrode the linear range was from 6 × 10−7 to 1 × 10−4 M catechol. The detection limit was low (1.82 × 10−7 M) while the quantification limit was 6 × 10−7 M. The sensitivity was five times higher than that corresponding to bare GC, proving the excellent electro-catalytic properties of the graphene-modified electrode. The practical applicability of the graphene-modified electrode was tested in tap water, obtaining an excellent recovery of 102%.