Remote underwater electrochemical sensing system for detecting explosive residues in the field

A mobile remote underwater electrochemical sensing system is described in this paper for detecting the explosive 2,4,6-trinitrotoluene (TNT) in the marine environment. The detection technology relies on using a carbon fiber as the working electrode, and applying a rapid and sensitive square-wave voltammogram for scanning. This submersible, pulsed-voltammetric, 3-electrode electrochemical sensor is mounted to a remotely operated surface vehicle with vision detection capability. The use of vision enhances the sensor package by allowing detection of and placement below detection limits. A wireless communication unit provides the ability to monitor and detect in real time. The detection scheme is based upon a stepwise reduction of the nitro aromatic groups on the explosive molecule first to hydroxylamines, and then followed by the conversion of the later to amine groups. The reduction potentials provide the method selectivity for a specific explosive, and the current required per unit time determines the concentration of the targeted explosive in an aqueous media. Successful field test data have been obtained which are comparable to those measured with laboratory instruments.