Investigation of the Persistence of Nerve Agent Degradation Analytes on Surfaces through Wipe Sampling and Detection with Ultrahigh Performance Liquid Chromatography-Tandem Mass Spectrometry

Abstract

The persistence of chemical warfare nerve agent degradation analytes on surfaces is important, from indicating the presence of nerve agent on a surface to guiding environmental restoration of a site after a release. Persistence was investigated for several chemical warfare nerve agent degradation analytes on indoor surfaces and presents an approach for wipe sampling of surfaces, followed by wipe extraction and liquid chromatography-tandem mass spectrometry detection. Commercially available wipe materials were investigated to determine optimal wipe recoveries. Tested surfaces included porous/permeable (vinyl tile, painted drywall, and wood) and largely nonporous/impermeable (laminate, galvanized steel, and glass) surfaces. Wipe extracts were analyzed by ultrahigh performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). UPLC provides a separation of targeted degradation analytes in addition to being nearly four times faster than high-performance liquid chromatography, allowing for greater throughput after a large-scale contamination incident and subsequent remediation events. Percent recoveries from nonporous/impermeable surfaces were 60-103% for isopropyl methylphosphonate (IMPA), GB degradate; 61-91% for ethyl methylphosphonate (EMPA), VX degradate; and 60-98% for pinacolyl methylphosphonate (PMPA), GD degradate. Recovery efficiencies for methyl phosphonate (MPA), nerve agent degradate, and ethylhydrogen dimethylphosphonate (EHDMAP), GA degradate, were lower, perhaps due to matrix effects. Diisopropyl methylphosphonate, GB impurity, was not recovered from surfaces. The resulting detection limits for wipe extracts were 0.065 ng/cm(2) for IMPA, 0.079 ng/cm(2) for MPA, 0.040 ng/cm(2) for EMPA, 0.078 ng/cm(2) for EHDMAP, and 0.013 ng/cm(2) for PMPA. The data indicate that laboratories may hold wipe samples for up to 30 days prior to analysis. Target analytes were observed to persist on surfaces for at least 6 weeks.

When Does Multiphase Chemistry Influence Indoor Chemical Fate?

“…Some studies have examined the persistence of pesticides or drug residues with transient sources on surfaces under laboratory and indoor field conditions. Many of these studies show lifetimes either longer than experimental timeframes or greater than a year following an initial period of rapid decay likely due to evaporation and equilibration if the compounds were applied directly on test surfaces at the start of the experiments. − In contrast, studies on more volatile or photolabile compounds such as nicotine and allethrin show lifetimes on the order of hours to days. , However, all of these studies are run under controlled conditions for only a few compounds and may not be generalizable to occupied indoor conditions with cleaning and realistic indoor chemistry. Many other studies have focused on detecting and quantifying a broad range of compounds in indoor dust, but because the indoor environment is approximately in a steady state in many cases, these studies are rarely able to elucidate any information about the fate or dynamics of these compounds.…”

Verification of exposure to chemical warfare agents through analysis of persistent biomarkers in plants

“…Analytical methods for the detection of chemical threat agents in matrices such as organic solvents, air samples, [11][12][13] soil, 14,15 wipe 16,17 and other solid materials have been broadly investigated. 18 However, detection of intact agents is oen not possible due to the relatively high volatility and reactivity of these chemicals.…”

Contaminated disposable rubber gloves as evidence samples after a chemical attack with nerve agents

“…The mentioned studies worked with solvents unsuitable for GC; moreover, the contaminated sample lifetime was not studied. Willison 25 demonstrated considerable resistance of G‐agent degradation products (up to 7 weeks) on various surfaces including vinyl, latex, or laminate.…”