Differential Mobility Spectrometry for Inorganic Filtration in Nuclear Forensics

Differential mobility spectrometry (DMS) is applied to the analysis of inorganic mixtures relevant to nuclear forensics. Three primary components of potential radiological dispersal devices (RDDs), cobalt, cesium, and strontium, were studied by DMS to demonstrate rapid sample cleanup when coupled to mass spectrometry. Nanosprayed salt solutions comprised of stable analogs, as proxies to these radioisotopes, and isobaric interferents were introduced to DMS. The DMS effluent was directly coupled to a mass spectrometer to confirm the elemental identity of the separated clusters. DMS dispersion plots demonstrated distinctive elemental separation from both atomic and molecular interferents. These results support the potential use of DMS as a means of rapid separation for inorganic analyses prior to analysis in a field portable mass spectrometer. The mechanism for this process is speculated to involve dynamics of solvent cluster formation under the influence of the alternating high and low electric fields of the DMS.