Real-time Analysis and Clustering of Single-particle Mass Spectrometer Data
Paul Haubenwallner, Ellen-Iva Rosewig, Robert Irsig, Johannes Passig, Sven Ehlert, Andreas Walte, RALF ZIMMERMANN,
Rostock University and Photonion GmbH Abstract Number: 242
Working Group: Source Apportionment
AbstractSingle-particle mass spectrometer (SPMS) contributed substantially to our understanding of aerosols and atmospheric processes (Pratt and Prather, 2012). They are unique for their capabilities to address the particle’s mixing state and for their chemical coverage with e.g. metals (Passig et al. 2020) and polycyclic aromatic hydrocarbons (Passig et al. 2022). SPMS are real-time instruments, however, the complex data evaluation is performed after the measurements (Sultana et al., 2017), which disables on-line screening of hazardous particles and real-time risk assessment.
We are developing a real-time software for SPMS data including data acquisation, preprocessing, screening and clustering. The toolkit is designed to fully analyse many particles per second, which requires non-standard C++ code, integrable in other environments. The analysis begins with acquisation and conversion of raw data from the two time-of-flight mass analyzers into nominal data. Of note, the laser desorption/ionization in SPMS challenges the instrument’s dynamic range with both smallest signals from trace compounds and high ion currents causing detector saturation. The resulting baseline instabilities and detector ringing need to be corrected to prevent data misinterpretation. The much smaller nominal data is ready for chemical characterization. This is typically based on clustering algorithms, creating groups of particles, that share their chemical properties. We integrate the widespread ART2a (Gross, et al. 2010), continuously extending and re-organizing the cluster results and thus featuring the first real-time ART2a clustering in SPMS. Finally, we show fast real-time screening of SPMS mass spectra for safety-relevant particles and database matching.
Reference list
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