Hand-portable gas-detector array (GDA) for rapid field detection and identification of chemical threat

Abstract

In the case of accidents at chemical plants, during transportation of chemicals or during terrorist attacks, hazardous compounds may be released and may harm emergency personnel and population. To prevent this a simple chemical hazard monitor is required to help locate the dangerous area, its border, and the safe area, as recently pointed out by Overton¹ in a FACT editorial.

Normally, only one or a few compounds are released, but a wide range of compounds has to be considered and must be measurable. In such cases, single-compound detectors may not provide any information or may provide misleading information. Alternative systems that determine sum parameters will give insufficient information to make a decision plan for environmental-protection activities or intervention by firefighters. However, there is always the danger of failing to detect important toxic substances if only one sensing technology is used.

In principle, all relevant compounds can be measured at low concentrations by laboratory analysis. However, techniques for task forces in the field are usually limited to simple equipment^2,3 and are useful for only a limited range of substances. Making laboratory analytical techniques available to the firefighter is the first successful step in accident analysis. However, devices such as mobile GC/MS and optical systems^4,5 need to be operated by specially trained personnel. Furthermore, because of relatively high costs only few special-purpose forces use this equipment.

Given the large amount of chemical hazardous compounds produced nowadays and the frequency of accidents reported in the past and anticipated accidents in the future, guidelines with lists of the major fraction of hazardous substances have been established in the United States (Emergency Response Planning Guidelines, ERPG2⁶) and in Germany (Einsatz Toleranz-Werte: ETW, tolerable concentration values⁷). In addition to the substances in these lists, chemical warfare agents have to be considered, for example, in the case of terrorism.

Detecting these substances in the field has been the objective of incident detection and measurement device developments. One result of our development efforts is the portable gas detector array (GDA). Its analytical task, selected sensors, signal interpretation, and measuring strategy as well as first experiences from the fire brigades using the prototype instruments are presented here. © 2000 John Wiley & Sons, Inc. Field Analyt Chem Technol 4: 195–203, 2000