Research Highlights

Technology Performance Summary: Nextteq Civil Defense 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: Nextteq Civil Defense Kit

Sample Types Evaluated for Indication of:

• Sarin and sulfur mustard in vapor using color tubes
• Nerve agents sarin and VX and sulfur mustard in liquid using M8 paper, M9 paper, and 3-way paper
• VX on surface using M8 paper, M9 paper, and 3-way paper

Conclusions:
The Nextteq Civil Defense Kit:

• Color tubes reliably detected sulfur mustard in vapor (100% accuracy), but did not reliably detect sarin in vapor.
• M8 paper gave positive responses in two out of three challenges with sulfur mustard in deionized (DI) water. It gave no positive response when the hydrocarbon mixture interferent was also present, resulting in 33% accuracy.
• M8 paper did not respond to sarin in the DI water samples; however, all three VX samples showed a light yellow color, which indicated a positive result for sarin rather than VX. Note that those responses were recorded as correct since they were indicative of a nerve agent and provided a protective response for personnel.
• M8 paper showed a light yellow, positive response in two of the three challenges when the interferent was also present in the DI water sample. Thus, the overall accuracy for the M8 paper for VX was 83%.
• M9 paper detected sarin, VX, and sulfur mustard in liquid samples prepared with isopropyl alcohol (IPA) samples, but also gave positive responses to the blank solvent. The M9 paper did not detect any of the CWAs in liquid samples prepared with DI water.
• 3-way paper did not detect any CWAs in any liquid samples (i.e., DI water or IPA).
• Was capable of detecting VX on surface samples using the M8, M9, or 3-way paper. However, the M8 and 3-way paper showed a pink color when challenged with blank test coupons spiked only with the interferent. This was clearly different from the dark green color shown when the VX was also present.
• Responded within seconds when using the 3-way paper, M8 paper, or M9 paper and responded within minutes when using the color tubes.
• Uses relatively simple procedures for screening approaches (e.g., color tubes).

Technology Description and Requirements: This technology incorporates four different CWA screening approaches. Three are color-indicating papers (M8 paper, M9 paper, 3-way paper), and the fourth (color tubes) uses an electric pump (or hand pump) to draw air through five different color-indicating tubes simultaneously, with each tube providing an indication of one vapor phase CWA, including sarin and sulfur mustard. All five tubes must be in place in the five-port sampling holder. The electric pump is preset to draw the required 3.5 L of air through the tubes within a sampling period of 3.5 minutes.

Testing Methodology and Results: Vapor Sample 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. For this evaluation, a hydrocarbon mixture interferent was added to the blank and to the TIC 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 IPA or 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, M9, and 3-way paper involved applying a drop of the liquid sample to the 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, M9, and 3-way paper was conducted by pressing the paper onto the test sample and inspecting for color change.

Table 1: Summary of Nextteq Civil Defense 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).
^dWhen the interferent was also present in the water sample with VX, the Nextteq M8 paper showed the light yellow positive response in only two of the three challenges.
^eWhen sulfur mustard was present in water, the Nextteq M8 paper gave positive responses in two out of three challenges, but gave no positive responses when the interferent was also present.
^fTechnology also gave positive responses to blank solvent.

Contact: Eric Koglin

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