Electrochemical Tape-and-paper-based Sensors for the Detection of Inorganic Explosives

Description:
IEDs represent a global threat due to their destructive potential, easy access to raw materials, and online manufacturing instructions. Potassium chlorate, since its discovery, has been used as the principal constituent of chlorate-based explosives due to its strong oxidizing composition. The standard methods to detect chlorate are mainly designed for laboratory testing or rely on techniques that generate more complex data to interpret, such as Raman and capillary electrophoresis, and thus do not meet the requirements for in-field detection. Electroanalytical assays integrated with flexible substrates allow for user-friendly, inexpensive, portable, and disposable analytical devices. We developed an electrochemical tape-and-paper-based device for the in-field detection of chlorate. The sensing element of our device is an electrodeposited molybdate layer, as chlorate was reported to have a catalytic effect on the molybdate reduction. The sensing concept to detect chlorate relies on monitoring the change in redox activity of the molybdate sensing layer using cyclic voltammetry (CV). We have effectively demonstrated the detection and quantification of chlorate in solution with a limit of detection of 0.14 mg/mL. Additionally, we have performed an interferent study with sugar, commonly used as fuel in IEDs, and other common white household powders. We also evaluated the selectivity of the sensor by testing other oxidizers such as perchlorate, nitrate, and bromate. To prepare for the end-user, we tested combusted samples and evaluated different sample collection and handling methods, such as swiping solids. We designed encased prototypes to allow for an in-field presumptive test, storage, and transport for in-laboratory confirmatory tests. This research was made possible with the support of the National Institute of Justice (2017-DN-BX-0172).

Speaker: Carolina Vega - Indiana University-Purdue University Indianapolis