We demonstrate the coupling of desorption electro-flow focusing ionization (DEFFI) with in-source collision induced dissociation (CID) for the mass spectrometric (MS) detection and imaging of explosive device components, including both organic, e.g., trinitrotoluene and nitroglycerin, and inorganic components, e.g., potassium chlorate and cesium, from the ever expanding assortment of homemade explosives and energetic materials. We utilize in-source CID to enhance ion collisions with atmospheric gas, thereby reducing adducts and minimizing organic contaminants. Optimization of in-source CID for the detection of organic and inorganic explosive device components demonstrated contrasting MS response relationships. The transition from electrospray to corona discharge chemical ionization and asymptotic approach to an emitted-current limited regime was identified and unaffected by the analyte classification. DEFFI-MS and in-source CID enabled isotopic and molecular speciation of inorganic components, providing further physico-chemical information. The developed system facilitated the direct detection and chemical mapping of trace analytes collected with Nomex® swabs and spatially resolved distributions within artificial fingerprints from forensic lift tape. The incorporation of alternating acquisition methods for negative and positive mode MS, and/or at high and low in-source CID, enabled the simultaneous detection and imaging of both organic and inorganic compounds. The results presented here provide the forensic and security sectors a powerful tool for the detection, chemical imaging, and inorganic speciation of explosives device signatures.
Citation: Analytical Chemistry
Pub Type: Journals
Mass spectrometry imaging, desorption electro-flow focusing ionization, ambient ionization, explosive detection, inorganic, artificial fingerprints, forensics, chemical analysis