Electrochemical Determination of TNT, DNT, RDX, and HMX with Gold Nanoparticles/Poly(Carbazole-Aniline) Film-Modified Glassy Carbon Sensor Electrodes Imprinted for Molecular Recognition of Nitroaromatics and Nitramines

Abstract

Since nitroaromatic- and nitramine-type energetic materials, mostly arising from military activities, are persistent pollutants in soil and groundwater, on-site sensing of these hazardous chemicals has gained importance. A novel electrochemical sensor was designed for detecting nitroaromatic- and nitramine-type energetic materials, relying on gold nanoparticles (Au-nano), modified glassy carbon (GC) electrode coated with nitro-energetic memory-poly(carbazole-aniline) copolymer (Cz-co-ANI) film (e.g., TNT memory-GC/P(Cz-co-ANI)-Au-nano modified electrode). Current was recorded against concentration to build the calibration curves that were found to be linear within the range of 100-1000 mu g L-1 for 2,4,6-trinitrotoluene (TNT) and 2,4-dinitrotoluene (DNT): 50-1000 mu g L-1 for 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX). The corresponding limits of detection were 25 mu g L-1 for TNT, 30 mu g L-1 for DNT, and 10 mu g L-1 for both RDX and HMX, using nitro-energetic memory-GC/P(Cz-co-ANI)-Au-nano electrodes. These electrodes were used separately, and specific determinations were made in various mixtures of nitro-energetic materials. The developed method could be efficiently used in electroanalyzing nitroaromatics and nitramines in military explosives (i.e., comp B, octol, and comp AS). The sensor electrodes were specific for the tested nitro-energetic compounds and did not respond to paracetamol-caffeine-based analgesic drug, acetylsalicylic acid (aspirin), sweetener, and sugar that can be used as camouflage materials in passenger belongings. The developed method was statistically validated against the standard LC-MS reference method in contaminated clay soil samples containing TNT and RDX explosives.