Research Highlights

Technology Performance Summary: MSA Single CWA Detector 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: MSA Single CWA Detector

Sample Types Evaluated for Indication of: Sarin and sulfur mustard in vapor

Conclusions:
The MSA Single CWA Detector:

• Reliably detected sarin in vapor; however, there was a strong positive (yellow) response observed with the sarin challenge, and a weak (faint yellowish) response during the
  interferent testing at the base conditions. 
• Did not reliably detect sulfur mustard in vapor.
• Responded within minutes after completion of required pump strokes to draw sample.
• Has a relatively simple procedure.

Technology Description and Requirements: This device uses color-indicating tubes to detect sarin and sulfur mustard, with a hand pump to draw sample air through a single indicating tube at a time. Thirty compressions of the hand pump provide the required sample volume.

Testing Methodology and Results: 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 CWA gas at a ratio of 1:100 interferent mix to air flow.

Table 1: Summary of MSA Single CWA Detector 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.
^cAEGL = Acute Exposure Guide Level.
^dStrong positive (yellow) response was observed and a weak positive response was observed with the blank challenges.

Contact: Eric Koglin

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