This work describes the first exploration of a uniquely engineered, ordered host framework utilized for promoting thermal ionization for mass spectrometry (TIMS). This aluminum-based scaffold has known affinities for rare earth metals such as neodymium (Nd) and can incorporate the high work function metal, rhenium (Re). In contrast to other approaches for increasing ionization, such as resin beads and Pt-Re porous ion emitters (PIES), sample preparation is simplified, accelerated, and made more reliable by loading the sample in a suspension that is absorbed to the activator. After thermal ionization, we hypothesized that the well-dispersed, sponge-like network of Re in the thermally activated host structure would enhance Nd ionization more than in traditional agglomerations used for TIMS sample loading. Compared with standardized filaments loaded with phosphoric acid that require an additional benzene carburization step, the Nd ionization efficiencies (atoms detected relative to atoms loaded) for heated filaments containing our Re-bearing framework were similar. Electron microscopy demonstrated that not only was the scaffold material still present on the filament after TIMS analysis but, as hypothesized, it also retained some porosity. While these results are preliminary, they demonstrate similar engineered host structures can be modified to enhance ionization and meet the performance of traditional loading techniques with potential to expand across the periodic table. Thus, further experimentation using this tunable scaffold is likely to exceed ionization performance through more specific synthetic control over porosity and the incorporation of high work function metal(s).

Exploring an engineered rhenium-containing ordered framework as a porous ion emitter for thermal ionization mass spectrometry

ACS Spring Meeting 2021

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