Desorption electrospray ionisation mass spectrometric analysis of chemical warfare agents from solid‐phase microextraction fibers

Abstract

Desorption electrospray ionisation mass spectrometry (DESI-MS) was recently reported for the direct analysis of sample media without the need for additional sample handling. During the present study, direct analysis of solid-phase microextraction (SPME) fibers by DESI-MS/MS was evaluated with indoor office media that might be collected during a forensic investigation, including wall surfaces, office fabrics, paper products and Dacron swabs used for liquid sampling. Media spiked at the mg/g level with purified chemical warfare agents and a complex munitions grade sample of tabun, to simulate the quality of chemical warfare agent that might be used for terrorist purposes, were successfully analysed by DESI-MS/MS. Sulfur mustard, a compound that has not been successfully analysed by electrospray mass spectrometry in the past, was also sampled using a SPME fiber and analysed for the first time by DESI-MS/MS. Finally, the overall analytical approach involving SPME headspace sampling and DESI-MS analysis was evaluated during a scenario-based training live agent exercise. A sarin sample collected by the military was analysed and confirmed by DESI-MS in a mobile laboratory under realistic field conditions. Copyright # 2007 Crown in the right of Canada. Published by John Wiley & Sons, Ltd.The ending of the Cold War and the widespread acceptance of the Chemical Weapons Convention have reduced the likelihood of battlefield chemical weapons use, but there remains a serious concern worldwide that other parties may make use of chemical warfare agents against civilian or military targets. Sarin, a well-known nerve agent, was used by the Aum Shinrikyo sect in Japan in 1995 during an attack on the Tokyo underground transit system, during which twelve people were killed and thousands more were injured. Public concern about the use of chemical or biological warfare agents reached a new peak following the al-Qaeda terrorist attacks of September 2001 and the subsequent delivery of anthrax letters in Washington DC. These events heightened security concerns within many countries and considerable resources have been expended to improve both field-and laboratory-based detection and identification methods for chemical warfare agents (CWAs).Detection and identification methods for CWAs, their degradation products and related compounds have been thoroughly reviewed with different emphases on a number of occasions. [1][2][3][4][5][6][7] Many previous method developments were driven by the requirements of the military and their need to be able to detect and identify these compounds in typical battlefield samples, including, soil, [8][9][10][11] water, 10,12-15 air, 16,17 munitions or munition blocks, 9,18 and clothing. 8,9 Newer methods based on solid-phase microextraction (SPME) sampling followed by gas chromatography/mass spectrometry (GC/MS) analysis [19][20][21][22][23] and direct analysis by secondary ion mass spectrometry 24 have been reported for environmental analyses, but most literature methods have been based on analysis of sample ...

Internal energy distributions in desorption electrospray ionization (DESI)

“…Analytes present at the surface are extracted and carried by the offspring droplets into the atmospheric pressure interface of the mass spectrometer (MS). Since its introduction in 2004 [1], DESI has found numerous areas of application, including forensics [2][3][4][5][6][7][8], imaging [2, 3, 9 -11], metabolomics [12][13][14][15], pharmaceutics [8, 14, 16 -25], characterization of natural products [1,8,19], bacteria [26], polymers [27,28], proteins [1, 24, 29 -32], and explosives detection [4,8,[33][34][35][36][37]. Investigations into the fundamentals of the droplet dynamics and ionization mechanism have also been conducted through systematic measurements of the droplet size and velocity [38], computer simulations [39], surface charging effects [40], or more simply, by evaluating the mass spectra of various types of analytes in conjunction with variations in the experimental parameters [41].…”

Transmission mode desorption electrospray ionization

“…The ion cloud is created within the sample chamber and transferred into the mass spectrometer due to the pressure differential of the vacuum. In other work, solid-phase microextraction (SPME) fibers used to extract either vapors from the headspace of samples or analytes from solution have been inserted into an electrospray plume for DESI analysis [24,39]. In these instances, the surface area was sufficiently small relative to the electrospray plume and ionization of adsorbed surface analytes occurred as the plume traveled around the fiber.…”

Observation of allicin‐cysteine complex by reactive desorption electrospray ionization mass spectrometry for garlic

“…Today, DESI and reactive DESI techniques are becoming important tools in direct detection of chemicals under ambient conditions without sample workup. [29][30][31][32][33][34][35][36] Herein, we report our findings in the direct analysis of garlic by DESI and reactive DESI methods. By the DESI method, the highly reactive allicin and allyl methyl thiosulfinate could be observed directly.…”