detected as the oxidized sulfoxide derivative, which has a proton affinity significantly higher than that of the parent molecule. While it has been demonstrated that all three species can be detected with high sensitivity in laboratory studies using the same instrumental conditions, it is not obvious that this multiagent detection capability will be possible when this experimental methodology is deployed and used in working environments. For example, ammonia in laboratories can originate from human breath and would likely not be as abundant in Class A environments where workers are in DPE suits and might have to be added to the sampling flow. In addition, the extent of sample oxidation in ambient ionization sources is known to be dependent on source operating conditions and environmental factors such as the relative humidity.
Finding 4-8. MINICAMS are designed to monitor relatively large areas and alarm when levels exceed a specified limit. Although regarded as near-real-time detectors, they typically require 5 to 10 min for a single analysis. This is not particularly efficient when attempting to locate and define an area of agent contamination. For example, when exposure to agent is possible, MINICAMS sampling ports are moved over worker DPE suits to see if agent levels exceed 1 vapor screening level, pausing in four quadrants to take a measurement. This is a time-consuming procedure.
Recommendation 4-4. Procedures developed and optimized in laboratory environments for the real-time detection of chemical agents using ambient ionization mass spectrometry should be verified in all working environments where they are likely to be deployed, using actual sample materials (e.g., activated charcoal from filter beds and worker masks, DPE suit material, and polymer-coated concrete).
Recommendation 4-5. Procedures should be developed for using ambient ionization mass spectrometry (e.g., DART, large-area DESI) to check worker DPE suits for contamination when workers are exiting Class A work areas. This approach could greatly reduce the time required for this activity, including verification of the effectiveness of decontamination procedures carried out prior to DPE suit removal when agent is detected.
Finding 4-9. Mass spectrometric detection methodology is able to provide relative quantification of analyte species, including chemical agents, over several orders of magnitude with excellent linearity between concentration and response for both gas- and liquid-phase analytes with appropriate sampling and ionization methods. Absolute quantification can be provided with appropriate reference standards. This is true of the ambient ionization mass spectrometric methods as well. However, quantifying amounts of target species on surfaces and adsorbed in solid substrates is more problematical.
Recommendation 4-6. The Army should develop reference standards to permit calibration of mass spectrometric instruments using DART (or other deployed ambient ionization sources) for analysis of chemical agents in gases and liquids. In the case of gas-phase samples, it would be useful to develop a reference standard that reliably provides a vapor-phase concentration equal to 1 vapor screening level of the target agent,