Single Particle Characterization by Time-of-Flight Mass Spectrometry

Reents, W. D.; Downey, S. W.; Emerson, A. B.; Mujsce, A. M.; Muller, A. J.; Siconolfi, D. J.; Sinclair, J. D.; Swanson, Alistair G.

doi:10.1080/02786829508965311

Cited by 61 publications

(54 citation statements)

References 16 publications

(7 reference statements)

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“…These properties are crucial to model the climate effects of particles. Further, by collecting characteristic mass spectra for a variety of primary (i.e., directly emitted) aerosol sources, both of anthropogenic and biogenic origin, the technique can be applied for source-apportionment studies (Bhave et al 2001).In recent years, a number of instruments for on-line singleparticle analysis have been developed (Johnston and Wexler 1995;Weiss et al 1996;Reents et al 1995;Hinz et al 1996;Murphy et al 1997;Gard et al 1997;Reilly et al 1997;Hunt and Petrucci 2002;Thomson et al 2000). These instruments are similar in their concept, combining an aerosol inlet, a particlesizing technique, a particle-desorption/ionization technique, and subsequent mass spectrometric detection of the ions produced.…”

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confidence: 99%

Instrument Characterization and First Application of the Single Particle Analysis and Sizing System (SPASS) for Atmospheric Aerosols

Erdmann

Alessandro

Cavalli

et al. 2005

Aerosol Science and Technology

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We describe here the instrumental setup and first experiments with the mobile single particle analysis and sizing system (SPASS) for the on-line characterization of single atmospheric aerosol particles. Aerosols are introduced into the SPASS via a differentially pumped particle inlet system using an aerodynamic lens that forms a narrow particle beam. The particles are sized with a two-laser velocimeter and subsequently desorbed and ionized with a highpower pulsed Nd:YAG laser operating at 266 nm. Positive and negative ions formed are simultaneously detected in a bipolar time-offlight mass spectrometer. Thus, the size and chemical composition of single aerosol particles can be characterized simultaneously in real time. The SPASS system has been installed inside a truck, creating a mobile unit. The performance of the SPASS in terms of mass resolution and sizing capabilities of the laser velocimeter has been evaluated. Positive and negative mass spectra from different types of particles have been obtained to identify "typical" peak patterns. The relative detection sensitivity depending on particle size and chemical composition was studied. Significant differences in detection sensitivities for different compounds were observed, demonstrating that the results obtained from ambient single particle measurements are strongly biased and dominated by "easy-to-detect" particles. The instrument performance is illustrated with results from a 24 h measurement period during winter in Milan, Italy. The period encompasses two meteorologically different episodes, a period of stagnant conditions, where regional background pollutants contribute significantly and the aerosol is dominated by ammonium nitrate and sulfate, and a North-Foehn event, where accumulation mode particles are scavenged and the urban aerosol population is dominated by organic matter due to local emissions. INTRODUCTIONThe importance of aerosols in chemical and physical processes involved in, for example, air pollution (human health, acid deposition, and global warming), combustion (soot and soot precursors), materials synthesis and processing (nanoparticles and coatings), and clean-room technology has increased dramatically in the past years. Their physical and chemical characterization and the study of their composition and reaction mechanisms represent an area in which basic information is still needed (Andreae and Crutzen 1997). It has become important not only to perform bulk analysis of aerosol particles but also to be able to analyze single aerosol particles, on-line in real time (Peter 1996). This capability will allow us in particular to investigate the mixing state of the particles. In an internally mixed aerosol, all particles have roughly the same chemical composition, which can be a mixture of inorganic and organic components. Externally mixed particles show chemically different subpopulations, e.g., with a fraction of the particles dominated by organic compounds and another fraction dominated by inorganic compounds. The mixing state is of relevan...

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confidence: 99%

Instrument Characterization and First Application of the Single Particle Analysis and Sizing System (SPASS) for Atmospheric Aerosols

Erdmann

Alessandro

Cavalli

et al. 2005

Aerosol Science and Technology

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“…This potential is shown in on-line aerosol analysis, where laser desorption/ionization has been used to detect particles that are smaller than optical detection allows, i.e., d < 100 nm (Reents et al, 1995;Carson, Johnston, & Wexler, 1997;Reents & Ge, 2000;Kane, Oktem, & Johnston, 2001;Reents & Schabel, 2001). In contrast to the LIF as illustrated in this article, no fluorescent labeling is required and, furthermore, masses of the resulting product ions can be identified with this technique.…”

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confidence: 99%

Optical detection methods for mass spectrometry of macroions

Peng

Cai

Chang

2004

Mass Spectrometry Reviews

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I. Introduction 00 II. Macroion Detection Methods 00 A. Energy‐Sensitive Detection 00 B. Charge‐Sensitive Detection 00 C. Photon‐Sensitive Detection 00 1. ELS 00 2. LIF 00 III Applications to Micron‐Sized and Nano‐Sized Particles 00 A. Ion Sources 00 B. Mass Analyzers 00 C. Detectors 00 1. ELS/Ellipsoidal Reflector 00 2. LIF/Ion Trap 00 IV. Conclusions and Outlook 00 Acknowledgments 00 References 00 Detection of macroions has been a challenge in the field of mass spectrometry. Conventional ionization‐based detectors, relying on production and multiplication of secondary electrons, are restricted to detection for charged particles of m/z < 1 × 106. While both energy‐sensitive and charge‐sensitive detectors have been developed recently to overcome the limitation, they are not yet in common use. Photon‐sensitive detectors are suggested to be an alternative, with which detection of macroions (or charged particles) by either elastic light scattering (ELS) or laser‐induced fluorescence (LIF) has been possible. In this article, we provide a critical review on the developments of novel optical detection methods for mass spectrometry of macroions, including both micron‐sized and nano‐sized synthetic polymers as well as high‐mass biomolecules. Design and development of new spectrometers making possible observations of the mass spectra of macroions with sizes in the range of 10–103 nm or masses in the range of 1–106 MDa are illustrated. The potential and promise of this optical approach toward macroion detection with high efficiency are discussed in practical aspects. © 2004 Wiley Periodicals, Inc.,Mass Spec Rev

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“…Others measure the ight time between two laser beams (Prather et al 1994;Yang et al 1996) or between two focal points of one laser beam (Weiss et al 1997) and correlate this measured velocity to the particle's aerodynamic diameter, d a (aerodynamic particle sizing). Another quite different approach involves preselecting a certain particle size for introduction into the instrument and chemically analyzing particles of just one size at a time (Reents et al 1995;Ge et al 1998). This method has the advantage of allowing for analysis of ultra ne (<100 nm) particles as small as 2 nm but the obvious disadvantage of missing most particles in a polydisperse sample at a given time, as only one narrow size slice can be analyzed at a given time.…”

Section: Introductionmentioning

confidence: 99%

Improved Lower Particle Size Limit for Aerosol Time-of-Flight Mass Spectrometry

Gälli¹,

Guazzotti²,

Prather³

2001

Aerosol Science and Technology

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The lower detectable particle size limit for a transportable aerosol time-of-ight mass spectrometer (ATOFMS) has been improved to 0.08 ¹m. This is lower than previously reported and has been achieved through instrumental modi cations described in this paper. The uncertainty in the size measurement of particles with aerodynamic diameters less than 0.18 ¹m does not allow for determination of an exact size for unknown particles, but particles with aerodynamic diameters as low as 0.08 ¹m can still be detected and chemically analyzed. A calibration curve covering the size range 0.18 -2.1 ¹m is presented. Simultaneously acquired positive and negative ion mass spectra of an individual 0.08 ¹m polystyrene latex sphere and an ambient particle with an aerodynamic diameter of 0.18 ¹m or less obtained with a transportable ATOFMS instrument are shown. The ability to precisely size and chemically analyze particles from a polydisperse sample down to 0.18 ¹m makes ATOFMS unique from other single particle mass spectrometry instruments.

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Single Particle Characterization by Time-of-Flight Mass Spectrometry

Cited by 61 publications

References 16 publications

Instrument Characterization and First Application of the Single Particle Analysis and Sizing System (SPASS) for Atmospheric Aerosols

Instrument Characterization and First Application of the Single Particle Analysis and Sizing System (SPASS) for Atmospheric Aerosols

Optical detection methods for mass spectrometry of macroions

Improved Lower Particle Size Limit for Aerosol Time-of-Flight Mass Spectrometry

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