Publication details
LOW-COST “GREEN” SENSORS BASED ON GRAPHITE NANOMATERIALS PREPARED FROM PENCIL LEADS WITH THE AID OF A 3D POSITIONING SPARKING DEVICE FOR THE SENSITIVE DETECTION OF NITROAROMATIC EXPLOSIVES
| Authors | |
|---|---|
| Year of publication | 2019 |
| Type | Article in Proceedings |
| Conference | XX Euroanalysis |
| MU Faculty or unit | |
| Citation | |
| Keywords | low-cost green sensors; graphite nanomaterials; raman spectroscopy,; scanning electron microscopy; cyclic voltammetry; electrochemical impedance spectroscopy; nitroaromatic explosives |
| Description | We report on the straightforward preparation of graphite nanomaterials (GNMs) through a direct graphite-to-substrate electric discharge at ambient conditions at 1.2 kV between pencil leads and low-cost graphite screen-printed electrodes (SPEs). The so-modified sparked GNM-SPE was characterized by Raman spectroscopy, scanning electron microscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. GNM-SPE sparked electrodes endowed sensitivity to plain SPEs to the cathodic voltammetric detection of various nitroaromatic explosives. Different commercially available pencil leads including “graphite pencil” (Faber-Castell, Castell 9000) of different degrees of hardness (4H, 2H, HB, 2B and 4B), “high-purity graphite leads” (Pilot, ENO-G, HB), “needle-crystal leads” (Uni-ball, Uni, HB) and “nanodiamonds leads” (Uni-ball, Nano-Dia, HB) were examined. Taking as criterion the highest response to the electro reduction of 2,4,6-trinitrotoluene (TNT), Castell 9000 (2B) pencil was selected as optimum. SPEs that have been modified with 200 sparking cycles showed an excellent repeatability (RSD50ppb = 1.8%, n=5), reproducibility (RSD10ppb = 3.0% and RSD50ppb = 2.8%, n=5) and linear response over the concentration range 1-100 ppb TNT. Data fit the equation I (µA) = (0.0137 ± 0.0002) [TNT(ppb)] - (0.0043 ± 0.0020), R2 = 0.9989, while the limit of detection based on the 3?/m criterion was calculated 0.44 ppb. The interference effect of other nitroaromatic explosives and masking compounds, which are used to hinder the detection of TNT, was extensively investigated. Moreover, GNM-SPE sparked electrodes were successfully applied to the determination of TNT in drinking water samples fortified with 2, 5 and 10 ppb TNT. Recovery was from 101±8 to 109±7%. Results demonstrated a new type of GNM-SPE low cost electrodes lend themselves to extremely simple preparation while offering enhanced detection capabilities and a wide-scope of applicability. Remarkably, GNM-SPE sparked electrodes can be prepared on-demand, within 3-4 min, through a totally green and solution-free method that requires only a pencil lead and a power supply. |