Differential Mobility Spectrometry–Mass Spectrometry for Atomic Analysis

Abstract

Analysis and separation of atomic ions within a portable setting are studied in forensic applications of radiological debris analysis. Ion mobility spectrometry (IMS) may be used to show separation of atomic ions, while the related method of differential mobility spectrometry (DMS) has focused on fractionation of primarily molecular components. We set out to investigate DMS as a means for separating atomic ions. We initially derived the differential ion mobility parameter, alpha, from classic empirical IMS data of atomic ions, cesium and potassium, each showing its own distinct form of alpha. These alpha functions were applied to DMS simulations and supported by analytical treatment that suggested a means for a rapid disambiguation of atomic ions using DMS. We validated this hypothesis through the prototype cesium-potassium system investigated experimentally by DMS coupled to mass spectrometry (MS). Such a feature would be advantageous in a field portable instrument for rapid atomic analyses especially in the case of isobaric ions that cannot be distinguished by MS. Herein, we first report this novel method for the derivation of alpha from existing field dependent drift tube ion mobility data. Further, we translate experimental DMS data into alpha parameters by expanding upon existing methods. Refining the alpha parameter in this manner helps convey the interpretation of the alpha parameter particularly for those new to the DMS field.

Differential mobility spectrometry/mass spectrometry history, theory, design optimization, simulations, and applications

“…Examples of improved separations due to chemical‐clustering will be shown in Section Improvement of peak capacity with transport gas chemical modifiers . In some instances with elemental ions, Type A behavior appeared to be occurring in the absence of clustering agents, which suggests polarization may also contribute to Type A behavior (Sinatra et al, ). However, it is unclear how pure the transport gases were during these observations as trace levels of moisture can produce significant clustering effects.…”

Differential Mobility Spectrometry-Mass Spectrometry (DMS-MS) for Uranium Ion Prefiltration to Improve Isotope Ratio Analysis

“…Usually, DMS CV scans are performed in the timescale of milliseconds to a few seconds, and has been successfully coupled to MS for several applications. [34][35][36][37][38] Previously, we have reported the implementation of DMS-MS for the separation and detection of inorganic species 39,40 and, more recently, for the separation of metal complexes. 41…”

Differential Mobility Spectrometry-Mass Spectrometry (DMS-MS) for Uranium Ion Prefiltration to Improve Isotope Ratio Analysis

“…Usually, DMS CV scans are performed in the timescale of milliseconds to a few seconds, and has been successfully coupled to MS for several applications. [34][35][36][37][38] Previously, we have reported the implementation of DMS-MS for the separation and detection of inorganic species 39,40 and, more recently, for the separation of metal complexes. 41 While DMS has demonstrated its capability for rapid ion pre-filtration, separation and elimination of chemical interference, the portability of DMS coupled to a fieldable MS system can be potentially used for field screening and characterization of radionuclides and their fission fragments.…”