In-source collision induced dissociation of inorganic explosives for mass spectrometric signature detection and chemical imaging

• In-source CID enhanced detection of elemental inorganics up to 1000-fold.
• In-source CID optimization of polyatomic oxidizers enhanced detection up to 100-fold.
• Optimal CID identified at transition from breaking ionic salt to molecular anion bonds.
• Trace detection of inorganic explosives at nanogram levels was demonstrated.
• Oxidizer particles were chemically imaged directly from latent fingerprints.

The trace detection, bulk quantification, and chemical imaging of inorganic explosives and components was demonstrated utilizing in-source collision induced dissociation (CID) coupled with laser desorption/ionization mass spectrometry (LDI-MS). The incorporation of in-source CID provided direct control over the extent of adduct and cluster fragmentation as well as organic noise reduction for the enhanced detection of both the elemental and molecular ion signatures of fuel-oxidizer mixtures and other inorganic components of explosive devices. Investigation of oxidizer molecular anions, specifically, nitrates, chlorates, and perchlorates, identified that the optimal in-source CID existed at the transition between fragmentation of the ionic salt bonds and molecular anion bonds. The chemical imaging of oxidizer particles from latent fingerprints was demonstrated, including both cation and anion components in positive and negative mode mass spectrometry, respectively. This investigation demonstrated LDI-MS with in-source CID as a versatile tool for security fields, as well as environmental monitoring and nuclear safeguards, facilitating the detection of elemental and molecular inorganic compounds at nanogram levels.

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