Detection of fuel‐oxidizer explosives utilizing portable capillary electrophoresis with wipe‐based sampling

Abstract

Portable analytical instrumentation that can provide an alarm indication for the presence of explosives and related components is critical for the identification of explosives‐based hazards and threats. Many explosives incident reports involve an inorganic oxidizer‐fuel mixture which can include pyrotechnics, fireworks, flash powders, black powders, black powder substitutes, and improvised or homemade explosives. A portable CE instrument with targeted analysis of common inorganic oxidizer ions, for example, chlorate, perchlorate, and nitrate, was used here as a rapid detection platform. Unlike frequently used gas‐phase separation and detection instrumentation such as ion mobility spectrometry (IMS), an automated liquid extraction mechanism is required for CE separation using acetate paper sample collection wipes. Target inorganic oxidizers were inkjet‐printed onto sample wipes to investigate instrument response relative to the collected analyte spatial distribution. Overall, analyte signal intensities increased with off‐center sample deposition due to improved sample extraction from wipes and no change in response was observed for varied array distributions across wipes. The system demonstrated sub 200 ng detection limits for all target analytes, with further improvement when normalizing to an internal standard.

Interpol review of the analysis and detection of explosives and explosives residues

“…Krauss, S.T., Forbes, T.P., and Jobes D. reported on using gradient elution moving boundary electrophoresis (GEMBE) as a “robust electrokinetic separation technique” for the separation and detection of inorganic oxidizers frequently seen in explosives. They stated that nitrate, chlorate and perchlorate oxidizers were detected from low explosives and that many possible inorganic and organic fuels did not interfere, and even detected and separated nitrate in post-blast samples [ 352 ]. General Spectroscopy: Fluorescence, Luminescence, Spectrophotometric, UV, Chemiluminescence …”

DART-MS Spectral Similarity of Infrared Thermally Desorbed Solid Particulate and Solution Cast Propellant Samples

“…Energetic materials encompass a major class of contraband compounds targeted, though many others exist such as illicit narcotics and toxic industrial chemicals. , Homemade fuel-oxidizer explosives based on readily available inorganic oxidizers, propellants, and pyrotechnics remain among the most common charges for improvised explosive devices (IEDs) in the United States . As the global threat from homemade explosives continues, research has focused on characterizing established instrumentation as well as developing novel technologies to detect these low explosives. − A recent review provides details on the unique challenges presented by inorganic-based fuel-oxidizer mixtures and strategies for improved detection …”

Inorganic oxidizer detection from propellants, pyrotechnics, and homemade explosive powders using gradient elution moving boundary electrophoresis

“…CE has emerged as a selective orthogonal method to analytical techniques that provide structural or elemental characterization, enabling rapid and efficient separation of inorganic anions from complex mixtures. Both laboratory and portable CE systems have demonstrated separation of anions and cations relevant to explosive‐based applications, most commonly using capacitively coupled contactless conductivity detection (C 4 D) [2,18,28,32–37]. The simultaneous separation of both anions and cations using CE presents a challenge due to the opposing charges, requiring reversal of the electroosmotic flow (EOF) and applied voltage polarity for separation from a single sample injection [38,39].…”