Offline filter sampling of aerosols is a low cost and easily deployable method for long-term measurements. The subsequent analysis can, however, be cumbersome and time consuming. Filter measurements of fine particulate matter with an aerodynamic diameter of up to 2.5 μm (PM2.5) is a staple in air pollution measurements. For example: to understand the role organic aerosols (OA) have in the atmosphere in aspect of e.g., climate or health effect, it is crucial to know the molecular composition of OA. Usually, such data is gathered by offline filter sampling and laboratory analysis.

Currently there exists several types of extraction methods for collected PM2.5 filters. What many of them have in common is the need of several stages of preparation before the analysis can begin. Smaller pieces are cut out from the used filters and then, depending on the method, sonication, rinsing, drying, dissolving, and nebulizing follows before the sample is finally analysed.

In this project, we propose a far more streamlined workflow. The whole collected filter is placed in a thermal desorption multi-scheme chemical ionization inlet coupled to an Orbitrap mass spectrometer (TD-MION-Orbitrap). The MION allows for fast switching between multiple reagents and Orbitrap provides high mass resolution. While there have been previous, fruitful studies with TD-CIMS offline analysis of PM, our work would deliver a user friendly, no preparation required, quick and affordable analysis methodology for inspecting molecular constituents of ambient PM2.5.