Aerosol Mass Spectrometer for Simultaneous Detection of Polyaromatic Hydrocarbons and Inorganic Components from Individual Particles.

Online studies of single airborne particles represent a demanding challenge in aerosol chemistry. New technologies that help to unravel the role of ambient aerosols in earth climate and to assess local and specific health risks from air pollution are highly desired. Of particular relevance are polycyclic aromatic hydrocarbons (PAHs) from combustion processes that are associated with both acute and long-term health effects. Usually, online single particle analyses apply laser desorption/ionization (LDI) in a bipolar mass spectrometer, revealing elemental constituents and limited molecular information by detection of both positive and negative ions. Approaches for the detection of PAHs from single particles have been developed but the elemental information from LDI that allows particle classification and source apportionment is lost in that case. Here we present a novel laser desorption and ionization method delivering both the PAH-profile and the inorganic composition from the same, individual particle. Test measurements demonstrate the technique's capability to reveal the single-particle PAH-distribution in aerosols (mixing state) and its assignment to specific pollution sources in a new and direct way.