Airborne submicron particles (<1µm, SMPs) affect air quality, weather and climate. Their size and chemical composition determine possible risks to human health or the environment. Thus, precise knowledge about the sources and the atmospheric fate of SMPs is essential for assessment and developing effective control measures, especially of ultrafine particles. In addition, a detailed chemical analysis of SMPs can aid to better understand environmental processes in the atmosphere and possible effects on human health.
Despite the need to learn about the origin, behavior, mobility, fate, and toxicity of SMPs, attempts to analyze their chemical composition in the atmosphere are still rare. Considering their low mass, partial volatility and dynamic character, it is a great challenge to separate, catch and analyze the airborne SMPs.
Impactors are useful tools to separate and collect environmental particles from the air to analyze their chemical composition. Herein, we report our evaluation of commercially available and frequently deployed cascade impactors for their applicability of sampling airborne SMPs. We tested the following criteria: (1) a precise size separation or cut-off in the submicron range to enable size-dependent chemical analysis, (2) the collection of the greatest as possible particle mass, while preventing the evaporation of the volatile and semi-volatile fractions. Therefore, different impactors were connected inline between a customizable particle generation source, a flow reactor for dilution, mixing and aging, and a mobility particle size spectrometer. Our results so far indicate a great variability among impactors of the same model and highlight the difficulty of combining all these requirements in one device. However, after careful physical characterization, we plan to optimize the particle sampling for environmental SMPs chemical composition analysis. This project is financed by the Bavarian Ministry of the Environment and Consumer Protection.