Abstract
Abstract. We describe a novel inlet that allows measurement of both gas and particle molecular composition when coupled to mass spectrometric, chromatographic, or optical sensors: the Filter Inlet for Gases and AEROsols (FIGAERO). The design goals for the FIGAERO are to allow unperturbed observation of ambient air while simultaneously analyzing gases and collecting particulate matter on a Teflon® (hereafter Teflon) filter via an entirely separate sampling port. The filter is analyzed periodically by the same sensor on hourly or faster timescales using temperature-programmed thermal desorption. We assess the performance of the FIGAERO by coupling it to a high-resolution time-of-flight chemical-ionization mass spectrometer (HRToF-CIMS) in laboratory chamber studies of α-pinene oxidation and field measurements at a boreal forest location. Low instrument backgrounds give detection limits of ppt or lower for compounds in the gas-phase and in the picogram m−3 range for particle phase compounds. The FIGAERO-HRToF-CIMS provides molecular information about both gases and particle composition on the 1 Hz and hourly timescales, respectively for hundreds of compounds. The FIGAERO thermal desorptions are highly reproducible (better than 10%), allowing a calibrated assessment of the effective volatility of desorbing compounds and the role of thermal decomposition during the desorption process. We show that the often multi-modal desorption thermograms arising from secondary organic aerosol (SOA) provide additional insights into molecular composition and/or particle morphology, and exhibit changes with changes in SOA formation or aging pathways.
Highlights
Aerosol particles scatter and absorb radiation, influence cloud formation processes and properties, provide surfaces to facilitate multi-phase reactions, and affect trace gas concentrations by providing an adsorptive medium for semi-volatile gases
The FIGAERO is essentially a multi-port inlet manifold that operates in two distinct modes: (1) ambient air sampling with trace gas analysis during simultaneous particle collection on a PTFE filter via separate dedicated ports, and (2) temperature-programmed thermal desorption of the collected particles in ultrahigh purity (UHP) N2 with the detection of the desorbed vapors via a separate dedicated port
The moveable PTFE tray is compressed against the inlet face of the main manifold by a 6 mm thick stainless steel plate. This plate serves as the connection point to ambient air and UHP N2 used for the temperature-programmed thermal desorption
Summary
Aerosol particles scatter and absorb radiation, influence cloud formation processes and properties, provide surfaces to facilitate multi-phase reactions, and affect trace gas concentrations by providing an adsorptive medium for semi-volatile gases. We assess the capabilities of this inlet in terms of its particle collection efficiency, linearity, reproducibility, the magnitude of the instrumental background in the particle phase measurement and the associated minimum detectable concentration of an individual component For this purpose, we coupled the FIGAERO to a highresolution time-of-flight chemical-ionization mass spectrometer (HRToF-CIMS) (Aljawhary et al, 2013; Mohr et al, 2013; Yatavelli et al, 2012) to study α-pinene oxidation in laboratory chambers and to measure ambient air in the boreal forest of Finland. We discuss opportunities to infer information on volatility, partitioning, and thermal decomposition using the combined gas and particle thermal desorption data
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
