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

Abstract

Advancement in rapid targeted chemical analysis of homemade and improvised explosive devices is critical for the identification of explosives‐based hazards and threats. Gradient elution moving boundary electrophoresis (GEMBE), a robust electrokinetic separation technique, was employed for the separation and detection of common inorganic oxidizers from frequently encountered fuel‐oxidizer mixtures. The GEMBE system incorporated sample and run buffer reservoirs, a short capillary (5 cm), an applied electric field, and a pressure‐driven counterflow. GEMBE provided a separation format that allowed for continuous injection of sample, selectivity of analytes, and no sample cleanup or filtration prior to analysis. Nitrate, chlorate, and perchlorate oxidizers were successfully detected from low explosive propellants (e.g., black powders and black powder substitutes), pyrotechnics (e.g., flash powder), and tertiary explosive mixtures (e.g., ammonium nitrate‐ and potassium chlorate‐based fuel‐oxidizer mixtures). Separation of these mixtures exhibited detection without interference from a plethora of additional organic and inorganic fuels, enabled single particle analysis, and demonstrated semiquantitative capabilities. The bulk counterflow successfully excluded difficult components from fouling the capillary, yielding estimated limits of detection down to approximately 10 μmol/L. Finally, nitrate was separated and detected from postblast debris collected and directly analyzed from two nitrate‐based charges.

In-Line Thermal Desorption and Dielectric Barrier Discharge Ionization for Rapid Mass Spectrometry Detection of Explosives

“…This corroborated previous analysis of these samples by a counter-flow capillary electrophoresis technique. 44 The Dyno AP charge debris spectrum was dominated by the nitrate dimer (Figure S9(d)), matching previous electrophoresis analysis 44 and aligning with the multiple nitrate species composing the emulsion charge.…”

“…42 40,43 The black powder substitute, Blackhorn 209, exhibited an ion distribution dominated by nitrate-species and guanidine nitrate species (Figure S9(a)). 44 Figure 4 also displays the mass spectra from swipe sampling of postblast debris from a thermoplastic polymer pipe-based explosives device. These devices were created using fused deposition modeling (FDM), packed with various charges (e.g., dynamite [i.e., RDX and TNT], black powder, and an emulsion explosive), and detonated by a heated wire.…”

In-line Thermal Desorption and Dielectric Barrier Discharge Ionization for Rapid Mass Spectrometry Detection of Explosives

“…This corroborated previous analysis of these samples by a counter-flow capillary electrophoresis technique. 44 The Dyno AP charge debris spectrum was dominated by the nitrate dimer (Figure S6), matching previous electrophoresis analysis 44 and aligning with the multiple nitrate species composing the emulsion charge.…”

“…This particular propellant has previously demonstrated two particle distributions, one based on guanidine nitrate/potassium perchlorate and the other on traditional black powderspotassium nitrate/sulfur/carbon. 44 Previous works incorporating high temperature thermal desorption have detected the potassium perchlorate component of Blackhorn 209 as well. 40 Figure 4 also displays the mass spectra from swipe sampling of post-blast debris from thermoplastic polymer pipe-based explosives devices.…”

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

“…Krauss, S.T. et al demonstrated the utility of a wipe based commercial GreyScan ETD-100 capillary electrophoresis for the detection of several inorganic oxidizers including nitrate, chlorate and perchlorate and post combustion inorganic ions [ 351 ].…”