Simultaneous Elemental Composition and Size Distributions of Submicron Particles in Real Time Using Laser Atomization Ionization Mass Spectrometry

Reents, W. D.; Ge, Zhaozhu

doi:10.1080/027868200410886

Cited by 47 publications

(55 citation statements)

References 2 publications

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“…Achieving quantitative chemical information on aerosols using ion intensities produced by LDI has had limited success to date (Bhave et al 2002;Fergenson et al 2001;Gross et al 2000;Lee et al 2005;Smith et al 2002;Woods et al 2001). The most promising quantitative results have been obtained for LDI processes producing atomic ions (Lee et al 2005;Reents and Ge 2000). However, more detailed information on the organic species or the source producing the species contained within a particle is lost when the particle is ablated and ionized to the atomic level.…”

Section: Introductionmentioning

confidence: 99%

Using ATOFMS to Determine OC/EC Mass Fractions in Particles

Spencer

Prather

2006

Aerosol Science and Technology

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Historically, obtaining quantitative chemical information using laser desorption ionization mass spectrometry for analyzing individual aerosol particles has been quite challenging. This is due in large part to fluctuations in the absolute ion signals resulting from inhomogeneities in the laser beam profile, as well as chemical matrix effects. Progress has been made in quantifying atomic species using high laser powers, but very few studies have been performed quantifying molecular species. In this study, promising results are obtained using a new approach to measure the fraction of organic carbon (OC) associated with elemental carbon (EC) in aerosol particles using single particle laser desorption ionization. A tandem differential mobility analyzer (TDMA) is used to generate OC/EC particles by size selecting EC particles of a given mobility diameter and then coating them with known thicknesses of OC measured using a second DMA. The mass spectra of the OC/EC particles exiting the second DMA are measured using an ultrafine aerosol timeof-flight mass spectrometer (UF-ATOFMS). A calibration curve is produced with a linear correlation (R 2 = 0.98) over the range of OC/EC ion intensity ratios observed in source and ambient studies. Importantly, the OC/EC values measured in ambient field tests with the UF-ATOFMS show a linear correlation (R 2 = 0.69) with OC/EC mass ratios obtained using semi-continuous filter based thermo-optical measurements. The calibration procedure established herein represents a significant step toward quantification of OC and EC in sub-micron ambient particles using laser desorption ionization mass spectrometry.

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Section: Introductionmentioning

confidence: 99%

Using ATOFMS to Determine OC/EC Mass Fractions in Particles

Spencer

Prather

2006

Aerosol Science and Technology

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“…The PSL sphere surface is derivatized with sodium sulfonate groups, which is equivalent to a monolayer. In addition, the suspension of PSL spheres contains among other additives SLS, used to keep the particles dispersed (Reents & Ge 2000). During evaporation of the suspension-solvent the non-volatile additives stick to the PSL particles forming a Na-containing coating.…”

Section: Psl Particles With Rounded Sodium Lauryl Sulfate (Sls) Contamentioning

confidence: 99%

A High Resolution Study of the Effect of Morphology On the Mass Spectra of Single PSL Particles with Na-containing Layers and Nodules

Cai

Zelenyuk

Imre³

2006

Aerosol Science and Technology

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The interpretation and quantification of measurements of particle composition by laser ablation based single particle mass spectrometry is complex. Among the most difficult systems to quantify are internally mixed particles containing alkali metals and organics. The alkali atoms in such particles tend to suppress the formation of other ions sometimes to below the detection limit. Here we present a study of the behavior of single particle mass spectral peak intensities as a function of the amount of the sodium containing compounds deposited on the surface of 240 nm polystyrene latex (PSL) spheres. We generate three morphologically distinct and well defined coating types: uniform layers, cubic nodules and rounded nodules, and measure the individual particle mass spectra as a function of the vacuum aerodynamic diameter with nanometer resolution. The data show that the probability of detecting the PSL spheres depends on the amount of the alkali metal on the PSL sphere surface, its morphological distribution and the ablation laser power. The data suggest that PSL spheres with localized Na-containing nodules are easier to detect than those which are completely encapsulated. We show, for example, that at low laser power, PSL particles that are completely encapsulated with Na-containing compounds, whose weight fraction is close to 50%, cannot be detected, while 35% of PSL spheres with same amount of coating can be detected if coating is localized in nodules on a fraction of the particle surface.

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“…An instrument arrangement such as multilaser ablations whereby a surface pre-ablation occurs upstream of the ion source could more clearly distinguish between the surface and core portions of particles. Another instrument setup could fully ablate the entire particle by a laser atomization/ionization approach, 36 if possible for supermicrometer particles, and thereby eliminate concerns about the extent to which the spectrum reflects the overall composition rather than mostly that of the surface. Either instrumentation changes or experimental evidence to show that the current mixed surface/core analysis is adequate for source apportionment are required to address concerns regarding the first two receptor modeling assumptions.…”

Section: Aerosol Lams Requirements Formentioning

confidence: 99%

Aerosol Laser Ablation Mass Spectrometry of Suspended Powders from PM Sources and Its Implications to Receptor Modeling

Tan

Fila

Evans

et al. 2002

Journal of the Air & Waste Management Association

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Primary sources of particulate matter (PM) were analyzed by suspending powdered samples into an aerosol laser ablation mass spectrometer (LAMS). PM sources studied included vehicle exhaust particulates, dust from a nonferrous smelter, cement powder, incinerator fly ash, two coal fly ash samples, and two soils. Marker peaks signified certain PM source sectors: construction particles could be distinguished by abundant Ca and Ca compounds, fuel combustion was marked by elemental carbon clusters, and nonferrous industrial particles showed inorganic As, Cu, Pb, Zn, and SO x . In addition to the distinction between particles from these different source sectors, mass spectral results also showed that for a single source, different particle types existed, and among different sources within a sector, similar spectra were present. The aerosol LAMS results show the difficulty in differentiating among separate fly ash sources as well as among different soil samples. A particle class balance receptor model that measures the amount of specific particle types rather than the amount of a chemical component is suggested as a means of source apportionment when particle spectra with overlapping source possibilities occur. The assumptions and limitations of receptor modeling aerosol LAMS data are also described. In particular, methods need to be developed to account for the contribution of secondary sources. INTRODUCTIONIn Ontario, Canada, ~1900 premature deaths, 9800 hospitalizations, and many more minor illnesses each year are attributed to air pollution.1 The Ontario Medical Association estimates that these burdens combine to cost, conservatively, more than $10 billion every year, both in direct (e.g., increased hospitalizations and employee absenteeism) and indirect (e.g., premature deaths and mental suffering) costs.1 A better characterization of air pollution, which includes a significant particulate matter (PM) component of acid aerosols, SO 4 2-particles, and PM from primary emission sources, would improve the understanding of its adverse health effects.2 Also, apportionment of the PM among its identified sources would help in determining targeted regulatory paths to remediate the PM component of air pollution problems.Single particle laser mass spectrometry is an advanced technique recently applied to the characterization of ambient PM.3 Aerosol laser ablation or laser desorption/ ionization mass spectrometers typically sample PM directly from the environment into the vacuum source region of a time-of-flight mass spectrometer. Individual particles are then ablated allowing particle-to-particle chemistries to be monitored online. In contrast to conventional bulk filter collection of PM that requires subsequent offline sample preparation and analysis, aerosol laser ablation mass spectrometry (LAMS) provides rapid, real-time information on separate particles. A recent literature review of the technique was conducted by Suess and Prather.

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Simultaneous Elemental Composition and Size Distributions of Submicron Particles in Real Time Using Laser Atomization Ionization Mass Spectrometry

Cited by 47 publications

References 2 publications

Using ATOFMS to Determine OC/EC Mass Fractions in Particles

Using ATOFMS to Determine OC/EC Mass Fractions in Particles

A High Resolution Study of the Effect of Morphology On the Mass Spectra of Single PSL Particles with Na-containing Layers and Nodules

Aerosol Laser Ablation Mass Spectrometry of Suspended Powders from PM Sources and Its Implications to Receptor Modeling

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