Trace detection of inorganic oxidants using desorption electrospray ionization (DESI) mass spectrometry

Abstract

Abstract:© Versita Sp. z o.o. Received 9 March 2011; Accepted 24 May 2011 Keywords: Perchlorate and chlorate ions • DESI MS • Ambient ionization methods • Oxidants • ExplosivesDesorption electrospray ionization (DESI), an established ambient ionization method in mass spectrometry (MS) for the analysis of organic compounds, is applied here to trace detection of inorganic salts, including inorganic oxidants. In-situ surface analysis of targeted compounds, including nitrogen-, halogen-and sulfur-salts, down to sub-nanogram levels, was performed using DESI-MS. Successful experiments were carried out in both the negative and the positive ion modes; simple anions and cations as well as small cluster ions were observed. Various surfaces are examined and surface porosity effects were briefly explored. Absolute detection limits on porous polytetrafluoroethylene (PTFE) of 120 pg (surface concentration 0.07 ng mm ), were achieved for sodium chlorate and sodium perchlorate, respectively. The compounds of interest were examined in the presence of a hydrocarbon mixture to assess matrix effects: only a two-or three-fold decrease in the target ion intensity was observed. Commercial fireworks were analyzed to determine perchlorate salts in complex mixtures. This work demonstrates the potential applicability of ambient ionization mass spectrometry to forensic investigations involving improvised explosives.

Anions in pre‐ and post‐blast consumer fireworks by capillary electrophoresis

“…ICP, atomic fluorescence spectroscopy, and atomic emission spectroscopy were applied to analyze intact rockets and pyrotechnic fountains, in search of metallic content in the charges . Moreover, desorption ESI with MS was used for the analysis of a preblast rocket, and laser electrospray coupled with MS was utilized for the direct analysis of pre‐ and post‐blast samples from different sorts of surfaces . Additionally, CE with UV‐Vis detection was applied to analyze pre‐ and post‐blast samples of some consumer fireworks .…”

Analysis of Residual Explosives by Swab Touch Spray Ionization Mass Spectrometry

“…Explosive perchlorate compounds were also of interest in this study because of their widespread use [31]. The direct analysis of 5.0 mg of tetrabutylammonium perchlorate was analyzed in full scan negative ion mode to look for perchlorate ions, as well as in the positive ion mode to measure tetrabutylammonium (Figure 4).…”

Recent advances in ambient mass spectrometry of trace explosives

“…For example, Sokol et al demonstrated trace detection of chlorate, perchlorate, nitrate, and sulfate inorganic oxidizers from surfaces including glass, wood, metal, cotton, filter paper, and PTFE by DESI-MS. 111 Sub-nanogram sensitivities were achieved for sodium chlorate and sodium perchlorate on the majority of non-porous surfaces. 111 Similar to the implementation for peroxide-based explosive detection, Hernandes et al used EASI to detect ANFO (ammonium nitrate-fuel oil) fuel-oxidizer mixtures and rhodamine B-based antitheft device markers directly off of banknotes from simulated and actual ATM explosion thefts (Figure 8). 147 Unique markers from the ANFO were observed in negative mode, specifically, 24 Mg(NO 3 ) 3 − , and confirmed by high resolution ESI-FTMS (Fourier transform mass spectrometry).…”

“…107, 108 Similar to a number of classical MS platforms, ambient MS techniques enable the simultaneous or near-simultaneous detection of both organic and inorganic species. 89, 109–111 This aspect becomes vital in the consideration of explosives detection, specifically with homemade fuel-oxidizer mixtures and improvised explosive devices.…”