“Coupling of the LS-APGD Microplasma and Orbitrap Mass Spectrometry: Elemental and Isotope Ratio Mass Spectrometry Without Chromatography”

The Marcus group focuses on the development of mass spectrometric strategies that provide chemical and
isotopic information across a wide diversity of applications. Specifically, a novel microplasma ionization
source, the liquid sampling-atmospheric pressure glow discharge (LS-APGD) has proven valuable in
performing elemental, isotopic, and molecular species analysis. With regards to isotope ratio (IR)
measurements, the ionization source has been coupled to an ultrahigh resolution ThermoScientific Orbitrap
Mass Spectrometer, providing unprecedented mass resolution while delivering precision on-par with MCICP-
MS. Earlier eeort showed that the important geochronological pair of 87Sr and 87Rb could be separated;
a mass dieerence of one beta particle. The microplasma/Orbitrap coupling has been applied for highprecision
isotope ratio determinations of uranium in the presence of great ( >5000x) excesses of problematic
elements such as Pb and W; eliminating the need for complex separations prior to IR analysis. More
impressively, we have recently demonstrated the complete isotopic separation of the Nd and Sm isotopes;
again allowing for determinations without chemical separations. These measurements are made possible by
the implementation of the Spectroswiss FTMS Booster X2, which provides mass resolution in excess of
500,000 on an instrument that is commercially-specified to deliver 70,000 and dynamic ranges that cover up
to 7 orders of magnitude, while the base system is challenged beyond 5. Notably, recent eeorts have shown
sensitivity for Br and I determinations that are many orders of magnitude below ICP-MS, opening up new
applications for plasma source mass spectrometry. This presentation will provide experimental details of the
remarkably simple instrumentation, which holds the promise of performing challenging IR measurements WITHOUT
CHROMATOGRAPHY.