AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Aerosol Mass Spectrometer for On-Line Detection of Polycyclic Hydrocarbons as Well as Inorganic Cations and Anions from Single Particles
RALF ZIMMERMANN, Julian Schade, Robert Irsig, Martin Sklorz, Johannes Passig, Helmholtz Zentrum München and University of Rostock
Abstract Number: 411 Working Group: Instrumentation and Methods
Abstract Inhalation of Polycyclic Aromatic Hydrocarbons (PAHs) is a well-known cause of morbidity and mortality. Furthermore, PAHs play an important role in the climate system because of their specific optical properties and effects on the formation of secondary organic aerosols. However, data on their distribution in aerosols are limited. This is of particular concern since details about their mixing state are crucial to assess health effects. For example, PAHs may be equally distributed over the ensemble or could be concentrated within a specific sub-population, inducing local effects upon particle-in-lung deposition and potential cancer development. Consequently, novel on-line techniques addressing PAHs on a single-particle scale while providing source information are desired.
Our approach is based on Single Particle Mass Spectrometry. Herein, particles are introduced into vacuum and sized via laser velocimetry. Prior to ionization, organics are desorbed by an IR-pulse. Key idea of our method is a spatially formed ionization laser profile that facilitates simultaneous Resonance-Enhanced Multi-Photon Ionization (REMPI) of the desorbed plume and Laser Desorption/Ionization (LDI) of the residual with one single UV-pulse. Thus, we introduce a route to obtain the full LDI-information of both positive and negative inorganic ions for source apportionment combined with health-relevant PAHs via REMPI.
In contrast to previously reported methods, cations and anions from LDI can now be detected, together with fully-fledged PAH-spectra from REMPI. Because all ions are formed within one combined ionization step, no further laser beyond the two sources for conventional two-step approaches is required. The method allows detailed insight into the mixing state of PAHs on different particle types. First on-line experiments on combustion aerosols demonstrate the methods capabilities to unravel the distribution of health-critical PAHs in the particle phase in real time.