Desorption electrospray ionization mass spectrometric analysis of organophosphorus chemical warfare agents using ion mobility and tandem mass spectrometry

Abstract

Desorption electrospray ionization mass spectrometry (DESI-MS) has been applied to the direct analysis of sample media for target chemicals, including chemical warfare agents (CWA), without the need for additional sample handling. During the present study, solid-phase microextraction (SPME) fibers were used to sample the headspace above five organophosphorus CWA, O-isopropyl methylphosphonofluoridate (sarin, GB), O-pinacolyl methylphosphonofluoridate (soman, GD), O-ethyl N,N-dimethyl phosphoramidocyanidate (tabun, GA), O-cyclohexyl methylphosphonofluoridate (cyclohexyl sarin, GF) and O-ethyl S-2-diisopropylaminoethyl methyl phosphonothiolate (VX) spiked into glass headspace sampling vials. Following sampling, the SPME fibers were introduced directly into a modified ESI source, enabling rapid and safe DESI of the toxic compounds. A SYNAPT HDMS instrument was used to acquire time-aligned parallel (TAP) fragmentation data, which provided both ion mobility and MS(n) (n = 2 or 3) data useful for the confirmation of CWA. Unique ion mobility profiles were acquired for each compound and characteristic product ions of the ion mobility separated ions were produced in the Triwave transfer collision region. Up to six full scanning MS(n) spectra, containing the [M + H](+) ion and up to seven diagnostic product ions, were acquired for each CWA during SPME fiber analysis. A rapid screening approach, based on the developed methodology, was applied to several typical forensic media, including Dacron sampling swabs spiked with 5 microg of CWA. Background interference was minimal and the spiked CWA were readily identified within one minute on the basis of the acquired ion mobility and mass spectrometric data.

Recent Advances in Solid-Phase Microextraction for Forensic Applications

“…Specifically for this study, S-(À)-N-(trifluoroacetyl)-prolyl chloride was used as the chiral derivatizing agent, which was added directly to the urine sample matrix. [72][73][74] Recently, field portable GC-MS methods have been utilized in combination with SPME for analysis of CWAs in ceiling tile material using a rapid 1-min extraction procedure and compared with actual liquid standard concentrations for proper mass identification. 64 In order to compare and classify methamphetamine (MA) samples based on geographic locations, a study was performed analyzing samples from Japan and Thailand using SPME for comparing the purity of the samples.…”

Internal Energy Deposition in Dielectric Barrier Discharge Ionization is Significantly Lower than in Direct Analysis in Real-Time Mass Spectrometry

“…[1] Methods for forming ions under ambient conditions can be classified into three primary groups that are based on liquid solution sprays, [2,3] laser desorption from surfaces, [4][5][6] and plasma ionization. [7] Such ionization methods can be used to analyse samples in the open atmosphere without the need for ion source enclosure, which facilitates high-throughput screening applications, including in the analysis of pharmaceutical tablets, [8] forensic samples, [9][10][11] explosives, [12,13] narcotics, [14] chemical warfare agents, [15][16][17] and persistent organic pollutants, [18][19][20] and bacterial profiling. [21] Plasma-based ionization methods have the advantages that (i) solvents, fluid pumps, and lasers are not required, and (ii) such ion sources tend to be significantly less susceptible to ion suppression, in which the sample matrix can detrimentally affect analyte ionization efficiency, than spray-and laser-based ion sources.…”

Enhancing performance of liquid sample desorption electrospray ionization mass spectrometry using trap and capillary columns

“…This technique is used as a rapid analytical tool to provide efficient desorption and ionization of target compounds for mass spectrometric characterization. It has become very successful in the fast analysis of a variety of analytes including pharmaceuticals(2, 3), metabolites(4, 5), drugs of abuse(6, 7), explosives(8, 9), chemical warfare agents(10), and even intact tissues(11). Traditional DESI addresses solid samples deposited onto a surface.…”