Application of acetonitrile modified platinum electrode for electrochemical determination of nitroaromatic compounds

Abstract

Possibility of electrochemical determination of a nitroaromatic compounds was investigated by cyclic voltammetry and galvanostatic pulse technique on a platinum electrode in aqueous sodium chloride solutions (0.5M NaCl) with acetonitrile containing different concentrations of trinitrotoluene (TNT), as an example of nitroaromatic compound. Acetonitrile chemisorption on a platinum surface took place and when the supported electrolyte contained acetonitrile in concentration as low as 0.5vol% extend of it chemisorption achieved saturation and platinum surface became effectively modified. The obtained cyclic voltammograms showed three distinct reduction peaks in the potential range of -0.45 to -0.8 V (vs. an Ag/AgCl (3M KCl) reference electrode), which refer to the multi-step process of TNT reduction. The calibration curves of the dependence of the first peak current on the TNT concentration were linear in the ranges 4.4 - 638.4 μM and 0.11 - 4.40 μM for two different scan rates, 200 mV s-1 and 20 mV s-1, respectively. The detection limit was 0.11 μM. The accuracy of the method presented in this work was tested in river water and it was confirmed that TNT could be successfully detected by acetonitrile modified Pt electrode.