Description: We are part-way through the second phase of a 4-year program designed to develop a portable monitor for sensitive hazardous waste detection. The ultimate goal of the program is to develop our concept to the prototype instrument level. Our monitor will be a compact, portable instrument that will allow real-time, in situ, monitoring of hazardous wastes. This instrument will be able to provide the means for rapid field screening of hazardous waste sites to map the areas of greatest contamination. Remediation efforts can then focus on these areas. Our analysis approach is to excite atomic and molecular fluorescence by the technique of active nitrogen energy transfer (ANET). The active nitrogen is made in a dielectric-barrier (D-B) discharge in nitrogen at atmospheric pressure. Only a few emission lines or bands are excited for each hazardous species, so spectral resolution requirements are greatly simplified over those of other spectroscopic techniques. The D-B discharge is compact, 1 to 2 cm in diameter and 1 to 10 cm long. Furthermore, the discharge power requirements are quite modest, so that the unit can be powered by batteries. Thus an instrument based on ANET can readily be made portable. Our results indicate that ANET is a very sensitive technique for monitoring heavy metals and chlorinated hydrocarbons. We have demonstrated an overall detection sensitivity for most species that is at or below ppb levels. ANET alone, however, appears to be most successful in treating hazardous species that have been atomized. We are therefore developing a hybrid technique which combines a miniature, solid-state laser for sample collection and vaporization with ANET for subsequent detection. This approach requires no special sample preparation, can operate continuously, and lends itself well to compact packaging.
Date: December 31, 1996
Creator: Piper, L.G.; Hunter, A.J.R.; Fraser, M.E. & Davis, S.J.
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