Final Decision to Certify Hazardous Waste Environmental Technology
TNT RaPID Assay
(Trinitrotoluene in Water and Soil)
Certification No: 95-01-017
The Ohmicron TNT RaPID Assay System uses enzyme-linked immunosorbent assay (ELISA) technology. It differs from other systems in that polyclonal antibodies are supplied attached to magnetic particles. TNT in water is assayed directly; for soils, the system uses extraction with alkaline methanol. The immunoassay system is semi-quantitative. Provided that the materials are used properly, detection is possible at 0.25 to 5.0 ppb in water and 0.25 to 5.0 ppm in soil; ranges can be extended upward by dilution of the extracts. Quantitative readings about a selected target level are obtained in a microprocessor-equipped, hand-held, battery-operated photometer or a compact table top photometer supplied by the manufacturer, or a standard laboratory photometer. The calibration is not biased, but the user is instructed to select target levels so as to determine the degree of confidence in avoiding false negative results. The reaction with other nitroaromatics is insignificant except for 1,3,5-trinitrobenzene (a contaminant in technical grade TNT), HMX, RDX, Dinoseb, 2,4-dinitrophenol, and mononitroaromatics do not interfere. Differences in the extraction efficiency of TNT from various soils may cause positive or negative errors in the immunoassay results. Users should evaluate these factors before attempting to quantify results.
Great care is required and established safety measures must be observed in sampling and handling soil containing explosives. As with similar assays, certain temperature controls are required for reagent storage and for carrying out the assay. The assay should be used only by trained individuals to reduce operator-caused variability.
A copy of the published Certification Notice may be obtained by contacting us at:
Department of Toxic Substances Control
File last updated: October 9, 1996