Analysis and design of a multisensory array for explosive substances based on solid electrodes

The detection of explosives and explosive related compounds is a subject of importance in several areas including environmental health, de-mining efforts (land and sea) and security and defence against terrorist activity. The use of electrochemical methods is particularly attractive as many common explosives contain suitable chemical groups to be detected using electrochemical methods. The electrochemical detection of explosives and related compounds in solution using a virtual metal electrode array and differential pulse voltammetry was achieved. The multiple sets of voltammetric data were integrated using multivariate analysis and matched with known substances present in explosives. Seven explosive substances: 2,4-initrotoluene, 2,6-dinitrotoluene, 3,4-dinitrotoluene, 2-nitrotoluene, octogen (HMX), pentaerithrytol tetranitrate (PETN), trinitrotoluene (TNT) and cyclonite (RDX) and a taggant agent 2,3â� dimethylâ� 2,3â� dinitrobutane (DMNB) were subjected to analysis using four solid electrodes, namely glassy carbon, silver, gold and platinum in saline aqueous solutions to mimic an aquatic environment. The results obtained in Differential Pulse Voltammetry (DPV) from the different experiments with each electrode were combined to produce a single voltammogram, which was subjected to chemometric analysis using Partial Least Squares (PLS) and Principle Component Analysis Non-Iterative Partial Least Squares (PCA-NIPALS). A combination of the electrochemical signals obtained together with the use of chemometric analysis made it possible to discriminate between explosives and their mixtures and also to quantitate their concentration in saline solutions. These combinations created a mathematical array, which clearly separates the explosives, even if the electrochemical information is buried or mixed with the electrode background noise. © 2012 SPIE.