Desorption Electrospray Ionization Mass Spectrometry (DESI-MS) Analysis of Organophosphorus Chemical Warfare Agents: Rapid Acquisition of Time-Aligned Parallel (TAP) Fragmentation Data

摘要

Desorption electrospray ionization-mass spectrometric (DESI-MS) analysis has been applied to the direct analysis of chemical warfare agents spiked on a variety of sample media including soils, water, food products and indoor samples that could be collected during a forensic investigation following a chemical incident. Solid phase microextration (SPME) fibers were used in this investigation to sample the headspace above five organophosphorus chemical warfare agents, O-isopropyl methylphosphonofluoridate (sarin, GB), O- pinacolyl methylphosphonofluoridate (soman, GD), O-ethyl N,N- dimethylphosphoramidocyanidate (tabun, GA), O-cyclohexyl methylphosphonofluoridate (cyclohexyl sarin, GF) and O-ethyl S-2- diisopropylaminoethyl methylphosphonothiolate (VX). The exposed SPME fibers were introduced directly into a modified Z-spray electrospray (ESI) source, enabling rapid and safe DESI-MS analysis of the toxic chemical warfare agents. Time-aligned parallel (TAP) fragmentation data, which provides both ion mobility spectrometry (IMS) and tandem mass spectrometry (MSn, where n=2 or 3) data for an individual compound, was acquired for the first time for organophosphorus chemical warfare agents. Unique ion mobility profiles and up to six full scanning MSn spectra, containing the (M+H)+ ion and up to seven diagnostic product ions, were acquired for each chemical warfare agent during DESI-IMS-MSn analysis of the exposed SPME fiber analysis. A rapid screening approach, based on the developed methodology, was applied to several typical forensic media (Dacron sampling swabs, office furniture fabric and cardboard) spiked with 5 mug of chemical warfare agent. Background interference was minimal and the spiked chemical warfare agents were readily identified within a minute on the basis of the acquired ion mobility and mass spectrometric data.