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EPA Technology Performance Summary: Proengin AP2C Handheld  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 provide identification of hazardous samples

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

Technology  Evaluated: Proengin AP2C

Sample Types Evaluated  for Indication of:

• Sarin and sulfur mustard in vapor
• Sarin, VX (nerve agent), and sulfur mustard in  liquid
• VX on surface

Conclusions and/or  Recommendations:
The Proengin AP2C:

• Reliably detects sarin in vapor and liquids  (i.e., liquid samples prepared
  with deionized water [DI] water).
• Did not detect any sarin or sulfur mustard in liquid samples prepared with isopropyl alcohol (IPA). One explanation for the lack of successful detection with IPA samples may be that the instrument was not designed for application with non-aqueous solvents.
• Detected sulfur mustard in 5 out of the 6 liquid  samples prepared with DI water.
• Is capable of detecting VX in surface samples. The instrument’s response to VX in surface samples was acceptable, but false positives can occur. The instrument had no response to VX in liquid samples prepared with DI water or IPA.
• Did not reliably detect sulfur mustard in vapor samples. Information from the manufacturer indicated that instrument had a lower vapor detection limit than the concentration used in the test.
• Responds within 10 seconds for vapor testing;  within 10 seconds for liquid testing;
  and with 25 seconds for surface testing.

Technology  Description: The Proengin AP2C is a hand-held flame spectrometer that detects characteristic emissions from hazardous chemicals as they are consumed in a flame. The device burns hydrogen, supplied from a compact low-pressure cylinder inside the instrument. Sample air is continuously drawn through by an internal pump. Detection of a target chemical triggers an alarm from the AP2C, and the instrument provides identification and semi-quantitative readings for the detected chemical. Such readings take the form of series of five bars that successively turn orange depending on the intensity of response. Sulfur compounds, nitrogen compounds, phosphorus compounds, and arsenic compounds are each identified by separate sets of bars. The AP2C can also indicate the presence of hydrocarbons. An attachment device allows liquid samples (either neat samples or solutions) to be picked up by the device and vaporized into the inlet of the AP2C by means of a heating circuit.

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. An interferent was also used in this evaluation. A hydrocarbon mixture 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 added to both the blank and the CWA samples as an interferent, at 1% of the total volume. Table 1 lists the CWAs tested, the concentrations used, and the basis for those concentrations. The AP2C was tested by applying a drop of the liquid sample to one of the analyzer’s attachments and then heating the scraper while positioned in the inlet of the AP2C analyzer. All liquid sample testing was conducted at room temperature with 50% relative humidity.

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 AP2C was tested by scraping the center of a test coupon with one of the AP2C scraper attachments, and then heating the scraper while positioned in the inlet of the AP2C.

The summary of the Proengin AP2C evaluation results are  provided in Table 1.

^a A hydrocarbon mix was used as the interferent.
^b Temperature 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 isopropyl  alcohol (IPA) was used as the solvent in the liquid test.
^c AEGL = Acute Exposure Guide Level and RDT&E = Research, Development,  Test, and Evaluation Standards (Chemical Surety, Chapter 6: Army Regulation 50–6 • 26 June 2001)
^d The instrument detected the presence of sulfur mustard in only two of the three samples.
*     False positive