Opportunity at National Institute of Standards and Technology NIST
Vapor Detection in Forensic Chemical Analysis
Material Measurement Laboratory, Applied Chemicals and Materials Division
Please note: This Agency only participates in the February and August reviews.
|Tara Marie Lovestead
|Mark O McLinden
We have recently developed a new technique for quantitative vapor sampling that provides for low uncertainty analyses for even low volatility solutes. The method is called cryoadsorption and incorporates the combination of low temperature solute transpiration and high efficiency sorbents in a capillary carrier. Unlike conventional purge and trap methods, this technique can be used with low vapor pressure liquids and solids, and the technique provides measurements that can be described thermodynamically with the vant’ Hoff equation. So far we have used the method for explosives, fire retardants, and food spoilage markers. In the near future, we will apply the method to additional problems in the forensic sciences. This work will take two primary directions, both of which are consistent with the recent National Academy of Sciences report on critical needs within forensic science analysis. First, we will apply the original cryoadsorption technique to a variety of fire debris analysis. In this respect, we will use the method to sample and analyze residual accelerant and also to sample weathered accelerants. For the analysis of residual accelerant, we will analyze controlled burn patterns on wood substrates and apply the method to find the evaporation profile of the accelerant. This is required to confirm the presence of an accelerant, since such samples are never recovered intact. For weathered accelerant, we must use the capability to detect and determine more polar constituents. This is important in the detection of fuels spilled on soil, since in this environment, the fuel is decomposed to more polar oxygen containing compounds. The second major application of the technique is in the detection and determination of vapor or gaseous markers. In this application, we use the cryoadsorber as a platform for an immobilized reagent system. Current projects include the detection of vapor phase hydrogen peroxide (for explosive and incendiary detection) and for the detection of ninhydrin fixing bacteria, to locate grave soils (of illegally buried corpses).
Cryoadsorption; Forensic analysis; Vapor analysis;
Open to U.S. citizens
Open to Postdoctoral applicants