In recent years, more improvised explosive devices made with chlorate salts are reported. Indeed chlorate salts are easier to use and buy, as they are submitted to less regulations than other common oxidizing agents such as ammonium nitrate. For crime scene investigation and debris analyses, in-field sensing capabilities are needed. Microfluidic paper-based analytical devices are low-cost, portable, flexible, and simple to produce and to use. We are developing an electrochemical paper-based device to detect and quantify chlorate using a molybdate sensing layer. The redox reactions of the molybdate are catalyzed by chlorate and, thus, we can observe increases in current and shifts in the peaks of potential by electro-analytical techniques such as cyclic voltammetry. Our current work is focused on exploring the best conditions (pH, type of acid, etc.) for the electrodeposition of the molybdate layer and the detection of chlorate. We are also optimizing the preparation (priming and washing/drying steps of the stencil painted electrodes) and utilization procedure. After optimization of the devices we will test how the prototypes react in the presence of chlorate in different form (liquid, solid) pure and in mixture.<br/>Those paper-based devices can also be used for sample collection, storage and transport to laboratory for further confirmatory tests. The residues should be recoverable after the in-field presumptive test as the analyte plays the role of catalytic agent in the redox assay. Furthermore, the electrochemical detection is less sensitive to interference than commonly used colorimetric detection, and due to the catalytic action of the residues, a low limit of detection will be expected.

In-field electrochemical detection of chlorate for explosives assessment

256th National Meeting (2018)

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