Title: Coupling Multiple Particle Levitation with Mass Spectrometry: Simulation and Assessment of the Quadrupole Design
Members: Amy Brooke
About: Chemistry in atmospheric aerosol particles affects climate and human health. Particle levitation is a novel experimental approach in atmospheric research, enabling the study of chemistry in authentic surrogates of atmospheric aerosols. Such controlled, multi-day studies that attain a high chemical specificity can be achieved using single-particle levitation coupled to mass spectrometry. High measurement uncertainty due to slow experimental throughput is a major limitation of the technique, which could be improved with levitation of multiple particles simultaneously, but this requires evaluation. In this work, the methodology of coupling multiple particle levitation in a linear electrodynamic quadrupole to mass spectrometry is investigated through an assessment of the stable trapping and sequential retrieval of multiple particles, using the ion optics field and trajectory software SIMION. Two designs, a capped linear quadrupole and a segmented quadrupole are evaluated and compared. Using technical specifications developed with the client, optimal operation procedures are established to reduce particle deviation and instability and increase retrieval efficiency. The parameter space, which consists of electric field parameters and the purge gas rate, was evaluated and its sensitivity to mass assessed. Both designs accomplish trapping and retrieval of at least five particles simultaneously. Therefore, we find that coupling multi-particle levitation in a quadrupole with mass spectrometry is a feasible methodology, capable of enhancing the throughput of current instrumentation. Furthermore, it is especially reliable when using the novel segmented quadrupole design, over the capped linear quadrupole design, which enables a highly systematic particle retrieval mechanism with a 100% retrieval efficiency.
