Research Highlights

Technology Performance Summary: Anachemia C2 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: Anachemia C2 Kit

Sample Types Evaluated for Indication of:

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

Conclusions:
The Anachemia C2 Kit:

• Reliably detected sarin in vapor (i.e., 100% accuracy). A faint yellowish color occurred (indicative of neither positive nor negative response) in 2 of the 3 blank challenges at the low temperature and relative humidity conditions (defined in Table 1, footnote b).
• Did not reliably detect sulfur mustard in vapor. The color tubes only correctly detected sulfur mustard at base temperature and relative humidity conditions (defined in Table 1, footnote b). At the low and high conditions, the color tubes showed faint positive responses, but all blank and challenge runs produced the same color responses.
• The 3-way paper did not detect sarin, sulfur mustard, or VX in any liquid test samples.
• The 3-way paper reliably detected VX on surface. Note that the 3-way paper showed a pink color for blank test coupons spiked with interferent; however, when VX was present, the 3-way paper showed a dark green color.
• Color ticket response time was in minutes; response within 2 minutes due to reaction time needed for color change (simple procedure). Color tubes’ response time was in minutes; a few minutes needed for 40 pump strokes (relatively complex procedure). 3-way paper response time was in seconds; color change within 5 seconds (simple procedure).

Technology Description and Requirements: Colorimetric and reagent based indicators. This kit includes three distinct technologies for CWA detection. The 3-way paper indicates the presence of CWAs by means of a color change. The color ticket detects nerve agents based on acetylcholinesterase inhibition. With this technology, a reagent pad must first be moistened with clean water, and then exposed to the test atmosphere by means of a small pump. After exposure, pressing the detector body into the holder contacts a test paper with the reagent pad. A white color indicates the presence of an agent, and a blue color indicates no agent present. The color-indicating tube works by drawing sample air through a bed of solid reagent in a glass tube (a hand pump is included for drawing samples through one tube at a time); a color change in the reagent indicates the presence of the agent.

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 (1% of the total volume) 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 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 3-way paper was conducted by pressing the paper onto the test sample and inspecting for color change.

Table 1: Summary of Anachemia C2 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).
^dOnly proper responses at base temperature and relative humidity conditions.

Contact: Eric Koglin

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