Ion Mobility Spectroscopy as a means of detecting explosives in soil samples.

摘要

For a variety of reasons, including its ease of use and high sensitivity, an increased interest has been shown in the use of Ion Mobility Spectroscopy (IMS) for the qualitative analysis of explosives. We have developed techniques that allows IMS to be used for quantitative analysis as well, and have applied this capability to screening soil and water samples for the presence of explosives. The system utilizes the binding energy of the explosive molecules to the soil to produce a unique desorption profile. Combining this desorption profile with the ion mobility allows accurate, unambiguous differentiation of the explosive species and eliminates potential interferences. We have found it necessary to closely control the IMS temperatures, the desorption temperature, and, most importantly, the ion chemistry occurring in the IN4S source. We have designed and built a thermal desorption/IMS system that provides reproducible desorption and analysis of the analyte. We will demonstrate the importance of controlling the ion chemistry, and describe the construction and operation of the desorption system. Potential interferences, detection limits, selectivity, and reproducibility of the system will be described. We have utilized this system for the analysis of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), 2,4,6-trinitrotoluene (TNT), 2,3-dinitrotoluene, 2,4-dinitrotoluene, 2,6-dinitrotoluene, 3,4-dinitrotoluene (collectively referred to as DNT), ethyleneglycoldinitrate (EGDN), pentaerythritol tetranitrate (PETN), and nitroglycerine (NG) in both water and soil samples. In this paper, we will restrict our discussion to the analysis of TNT and RDX in soils. Those interested in the analysis of other explosives in soil, or the analysis of water samples, should contact the authors.