Research Highlights

Technology Performance Summary: Truetech M18A3 Kit for Chemical Warfare Agents

All Hazards Receipt Facilities (AHRFs) were developed to prescreen for chemical, radiochemical, and explosive hazards in samples collected during suspected terrorist attacks. The technologies used in AHRFs are intended to screen samples prior to a full analysis, helping protect responders, laboratory workers, and others from potential injury.

Evaluations of these technologies are summarized in the technology evaluation report, Testing of Screening Technologies for Detection of Chemical Warfare Agents in All Hazards Receipt Facilities. The chemical warfare agents (CWAs) included in the report were chosen because they might be used during, or develop as a by-product from, a terrorist attack.

The screening technologies are intended:

• To be rapid and qualitative
• To be simple to use and of relatively low cost
• To indicate if samples contain hazardous chemicals
  of concern.

Not all of the technologies evaluated were deemed suitable for the AHRF, although they might be useful for responders on the scene.

Technology Evaluated: Truetech M18A3 Kit

Sample Types Evaluated for Indication of:

• Sarin in vapor using color ticket
• Nerve agents sarin and VX and sulfur mustard in liquid using M8 paper
• VX on surface using M8 paper

Conclusions:
The Truetech M18A3 Kit:

• Color ticket reliably detected sarin in vapor (i.e., 100% accuracy).
• M8 paper failed to detect sarin, sulfur mustard, or VX in any liquid samples.
• Reliably detected VX on surface. Note that the M8 papers showed a pink color for blank test coupons spiked with interferent; however, when VX was present, the M8 paper showed a dark green color.
• Response time was approximately 3 minutes for vapor and liquid testing and 10 seconds for surface testing.
• Uses relatively simple procedures for both screening methods (e.g., color ticket).

Technology Description and Requirements: Colorimetric indicator and enzyme-based reagent. This kit includes two CWA screening technologies, M8 paper and a color ticket. The M8 paper is applicable to CWAs in liquid samples and on surfaces. The color ticket is based on acetycholinesterase inhibition and is intended for detection of nerve agents in the vapor phase. With this ticket, the presence of CWAs is indicated by a white color on the indicating pad.

Testing Methodology and Results: Vapor Phase Testing – Testing was conducted on one CWA at a time. The tested gases were generated by diluting a commercially obtained compressed gas standard. To evaluate the instrument, a flow of clean air passed through a clean air plenum, and an equal flow of air containing the tested gas passed through another plenum: the challenge plenum. The instrument was connected to a 4-way valve through which clean air, or the tested gas, flowed before being vented into a chemical laboratory hood. The instrument was first exposed to the clean air flow. After this, the 4-way valve was switched to the challenge plenum to deliver the tested CWA gas. The sequence of exposure to clean air, followed by exposure to the CWA gas, was carried out three times in succession for the instrument. This sequence was followed for each CWA and each test condition identified in Table 1. A hydrocarbon mixture interferent was added to the blank and to the CWA gas at a ratio of 1:100 interferent mix to air flow.

Liquid Sample Testing – Stock solutions of sarin, sulfur mustard, and VX were diluted in isopropyl alcohol (IPA) or deionized (DI) water to make the samples. The detection device was tested with three blank samples of the solvent used (IPA or DI water), and three samples of the test solution containing the CWA. If the instrument detected the CWA in at least one of the three tests with pure solvent, then the challenge was repeated with a hydrocarbon mixture interferent (1% of the total volume) added to both the blank and the CWA samples. Table 1 lists the CWAs tested, the concentrations used, and the basis for those concentrations. All liquid sample testing was conducted at room temperature with 50% relative humidity. Testing of the M8 paper involved applying a drop of the liquid sample to the test paper.

Surface Sample Testing – Glass slides served as the test surfaces. Samples were prepared by spiking 1 mg of neat VX on each glass slide to produce a surface loading of approximately 0.2 mg/cm². Test coupons were spiked in the morning of each test day and used immediately after spiking. Each test used three blank glass coupons and three glass coupons spiked with VX at room temperature and approximately 50% relative humidity. Interference tests were conducted by spiking approximately 1 mg of a hydrocarbon mixture per coupon onto both blank and VX-spiked coupons. The blank and spiked coupon tests were repeated at the same low and high temperature and relative humidity conditions used for the CWA vapor testing (defined in Table 1, footnote b). The evaluation of the M8 paper was conducted by pressing the paper onto the test sample and inspecting for a color change.

Table 1: Summary of Truetech M18A3 Kit Test Results

^aA hydrocarbon mixture was used as the interferent.
^bTemperature and relative humidity conditions for vapor tests were: Base = 20 °C and 50% relative humidity, Low = 10 °C and 20% relative humidity, and High = 30 °C and 80% relative humidity. DI water or IPA was used as the solvent in the liquid test.
^cAEGL = Acute Exposure Guide Level; LD₅₀ = Lethal dose to half the population; and RDT&E = Research, Development, Test, and Evaluation Standards (Chemical Surety, Chapter 6: Army Regulation 50-6, 26 June 2001).

Contact: Eric Koglin

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