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Methods of analyzing vapors in an IMS explosives/narcotics detector that is primarily designed for particle collection were investigated, with emphasis on nitroglycerin explosive, and acetic and benzoic acid contaminants in narcotics. A preconcentration step is required because expected vapor concentrations are low. NG adsorption and retention behavior on coated teflon filters that are compatible with the IMS sample desorption system is reported, including the effects of adsorbent, and sampling flow rate, time and volume. Similar investigations were carried out for acetic and benzoic acid vapors, and a gold-plated nickel mesh was selected as the most appropriate IMS-compatible filter for these materials. Vapor sampling flow rates and volumes are much lower than those used in particle sampling. Examples of NG and benzoic acid vapor detection in real and simulated applications are discussed.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only. |
