Generation of graphite nanomaterials from pencil leads with the aid of a 3d positioning sparking device: application to the voltammetric determination of nitroaromatic explosives

We report on facile generation of graphite nanomaterials (GNMs) with advanced electro catalytic properties through a direct electric discharge process between pencil leads and graphite screen − printed electrodes (SPEs) at ambient conditions at 1.2 kV. Various commercially available pencil leads of different degrees of hardness were examined. Sparked GNM − SPEs were characterized by Raman spectroscopy, SEM, CV, and EIS. Taking as criterion the highest response to the electro-reduction of nitro group of 2,4,6−trinitrotoluene (TNT) at −0.3 V at deoxygenated solutions, Castell 9000 (2B) pencil was selected as optimum. GNM − SPEs exhibited a linear response over the concentration range 1 − 100 ppb TNT, while the limit of detection (LOD) based on the 3σ/m criterion was calculated 0.44 ppb. The interference effect of other nitro − aromatic explosives and masking compounds, which are used to hinder the detection of TNT, was extensively investigated. The determination of TNT was also achieved by measuring the oxidation of the electrochemically generated hydroxylamine groups. In this format, each measurement was conducted with a new electrode polarized at −0.275 V for 2 min. At the cost of a slightly increased time of analysis, the anodic determination of TNT offered increased selectivity, applicability in non − deoxygenated solutions, linear response over the concentration range 1 − 50 ppb TNT and an LOD of 0.25 ppb. GN...
Source: Sensors and Actuators B: Chemical - Category: Chemistry Source Type: research