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Characterization of Nanoparticles from Spark Ablation
Published in Andreas Schmidt-Ott, Spark Ablation, 2019
The sections will start by briefly describing on-line characterization using two different advanced aerosol instruments that have been used to characterize spark-ablated particles. These systems can be connected to the nanoparticle production system. The first instrument that will be described is the aerosol particle mass (APM) analyzer that measures particle mass concentration. The second one provides chemical information about aerosol-generated particles and is called the aerosol mass spectrometer (AMS).
Solvent effects on chemical composition and optical properties of extracted secondary brown carbon constituents
Published in Aerosol Science and Technology, 2022
Kunpeng Chen, Nilofar Raeofy, Michael Lum, Raphael Mayorga, Megan Woods, Roya Bahreini, Haofei Zhang, Ying-Hsuan Lin
Real-time size-resolved mass distributions and chemical composition of aerosol particles were measured by a mini-Aerosol Mass Spectrometer coupled with a compact time-of-flight mass spectrometer (mAMS, Aerodyne Research Inc.) every 20 s during all experiments (Bahreini et al. 2005). Sensitivity and sizing capability of the instrument were calibrated regularly using dry, size-selected ammonium nitrate particles or dry polystyrene latex spheres. The raw data were analyzed as described previously (Allan et al. 2004). Given the accuracy of the mass calibrations (20 ppm), high-resolution analysis of the raw mass spectra was also carried out for m/z 20–115 amu to calculate the mass concentrations of all species except ammonium (Bahreini et al. 2012). A scanning electrical mobility spectrometer (SEMS, Brechtel Manufacturing Inc.) was used to determine the number concentration and size distribution of SOA from 10 to 800 nm with 140 bins. The sampled air from the chamber passed through a 30-cm-long diffusion dryer filled with silica gel (Sigma-Aldrich) and Purafil (Thermo Scientific) before reaching mAMS, SEMS, and the photoacoustic extinctiometer (PAX, described below). Details of calculations of the organic aerosol fraction (MFOA), particulate effective density (ρeff), and the total volume concentration of particles used to estimate the SOA mass concentration (CSOA) are provided in the online supporting information (SI) Text S1. Calculated values are summarized in Table S1. The CSOA was used subsequently to calculate online MAC.
A direct-reading particle sizer with elemental composition analysis for large inhalable particles
Published in Aerosol Science and Technology, 2022
James Sipich, Christian L'Orange, Kimberly Anderson, Christopher Limbach, John Volckens, Azer Yalin
The present work details the design and testing of an instrument for sizing based on settling velocity with the simultaneous determination of composition based on LIBS oriented to particles in the 20–100 μm range. Existing instrumentation such as cascade impactors, condensation particle counters and the Aerodynamic Particle Sizer (TSI Inc. Shoreview, MN) are designed for smaller aerosol sizes and are not appropriate for particles much larger than ∼10–20 µm due to aspiration issues and transmission losses (Volckens and Peters 2005). The aerosol mass spectrometer (Jayne et al. 2000) is an advanced direct-reading instrument capable of measuring both size and composition of aerosols, but only for particles <1 µm. A common sampling methodology for characterizing large particles in occupational settings involves active sampling and collection of particles onto filter media. These samples are typically sent to an off-site lab for analysis. However, post facto analysis via inductively coupled plasma mass spectroscopy, or similar processes, is expensive and may take weeks to return the results (Su et al. 2014; Wilschefski and Baxter 2019). The delay in receiving results means that dangerous levels of contaminants may continue to be present for weeks or months after exposure assessment occurs.
On-line and off-line analysis of particles from rock, sediment, sand, snow water and atmospheric air at the Jungfraujoch site, using single-particle laser mass spectrometry
Published in Aerosol Science and Technology, 2021
Christof Barth, Klaus-Peter Hinz, Bernhard Spengler
It is particularly difficult to differentiate between externally and internally mixed particles when particle ensemble measurements are used, as in the case of MPMS. Although MPMS allows to quantitatively determine the chemical composition of particles and to identify certain particle sources by Positive Matrix Factorization (PMF), the results are based on many parameters and vary depending on the interpretation of the initially determined factors (Ulbrich et al. 2009). Another prerequisite for a reliable determination of particle sources using PMF is the availability of a sufficiently large data set. It is therefore important to be able to measure individual particles separately. Single-particle aerosol mass spectrometry offers optimal conditions for this, as individual particles are vaporized, ionized and detected one after another. Even a small number of measured particles makes it possible to draw conclusions about the origin of the particles and environment to which these particles were exposed (Hinz et al. 1999).