Research Highlights

Technology Performance Summary: Proengin AP4C Handheld Detector for Toxic Industrial Chemicals

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 Toxic Industrial Chemicals in All Hazards Receipt Facilities. The toxic industrial chemicals (TICs) 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: Proengin AP4C

Sample Types Evaluated for Indication of:

• Hydrogen cyanide, cyanogen chloride, arsine, and hydrogen sulfide in vapor
• Cyanide in liquid

Conclusions:
The Proengin AP4C:

• Reliably detected the presence of hydrogen cyanide, arsine, and hydrogen sulfide in vapor samples but did not have reliable responses for indicating cyanogen chloride in vapor form. (The instrument gave an incorrect response to hydrogen cyanide at the low temperature and relative humidity condition; therefore, it was determined to have an overall accuracy of 75% for detecting hydrogen cyanide with false negative rates of 25%.)
• Did not have reliable responses for indicating cyanide in liquid samples.
• Typically responded within a few seconds. It took less than one minute both to install the attachment for liquid sampling and obtain instrument response.
• Would periodically require low-pressure hydrogen supply replacements, if used regularly (12-hour supply life maximized by turning instrument on and off).
• Uses a relatively simple procedure.

Technology Description and Requirements: The Proengin AP4C 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 AP4C, and the instrument provides identification and semi-quantitative readings for the detected chemical. Such readings take the form of a 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 AP4C 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 AP4C by means of a heating circuit.

Testing Methodology and Results: Vapor Sample Testing – Testing was conducted on one TIC 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 TIC gas. The sequence of exposure to clean air, followed by exposure to the TIC gas, was carried out three times in succession for the instrument. This sequence was followed for each TIC and condition identified in Table 1. For this evaluation, a hydrocarbon mixture interferent was added to the blank or TIC gas at a ratio of 1:100 interferent mix to air flow.

Liquid Sample Testing – Because cyanide is water-soluble, water was used as a solvent. To simulate potential interfering sample types that might be encountered, samples were prepared using deionized water (DI), municipal tap water, and DI water containing 3.0% by weight sodium chloride. Each screening technology was tested with three blank samples and with three samples containing the cyanide. If the instrument failed to detect a TIC in all three challenge samples with the DI water matrix, then no tests were conducted with that TIC in tap or salt water.

Table 1: Summary of Proengin AP4C Test Results

^a A hydrocarbon mixture 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 was used as the solvent in the liquid test.
c AEGL = Acute Exposure Guide Level, TEEL = Temporary Emergency Exposure Limit, and 0.1 x Oral LD₅₀ = one-tenth of the oral dose that would be lethal to half the population (LD₅₀ ).
^d The instrument did not correctly identify hydrogen cyanide at low temperature and relative humidity conditions.
^e The instrument correctly responded to 3 of 6 samples.

Contact: Eric Koglin

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