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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 108, NO. D7, 8424, doi:10.1029/2001JD000660, 2003

A comparison of particle mass spectrometers during the 1999 Atlanta Supersite Project

Ann M. Middlebrook

NOAA Aeronomy Laboratory, Boulder, Colorado, USA


Daniel M. Murphy

NOAA Aeronomy Laboratory, Boulder, Colorado, USA


Shan-Hu Lee

NOAA Aeronomy Laboratory, Boulder, Colorado, USA


David S. Thomson

NOAA Aeronomy Laboratory, Boulder, Colorado, USA


Kimberly A. Prather

Department of Chemistry, University of California, Riverside, California, USA


Ryan J. Wenzel

Department of Chemistry, University of California, Riverside, California, USA


Don-Yuan Liu

Department of Chemistry, University of California, Riverside, California, USA


Denis J. Phares

Departments of Mechanical Engineering and Chemistry and Biochemistry, University of Delaware, Newark, Delaware, USA


Kevin P. Rhoads

Departments of Mechanical Engineering and Chemistry and Biochemistry, University of Delaware, Newark, Delaware, USA


Anthony S. Wexler

Departments of Mechanical Engineering and Chemistry and Biochemistry, University of Delaware, Newark, Delaware, USA


Murray V. Johnston

Departments of Mechanical Engineering and Chemistry and Biochemistry, University of Delaware, Newark, Delaware, USA


José L. Jimenez

Aerodyne Research Incorporated, Billerica, Massachusetts, USA


John T. Jayne

Aerodyne Research Incorporated, Billerica, Massachusetts, USA


Douglas R. Worsnop

Aerodyne Research Incorporated, Billerica, Massachusetts, USA


Ivan Yourshaw

Departments of Environmental Engineering Science and Chemical Engineering, California Institute of Technology, Pasadena, California, USA


John H. Seinfeld

Departments of Environmental Engineering Science and Chemical Engineering, California Institute of Technology, Pasadena, California, USA


Richard C. Flagan

Departments of Environmental Engineering Science and Chemical Engineering, California Institute of Technology, Pasadena, California, USA


Abstract

During the Atlanta Supersite Project, four particle mass spectrometers were operated together for the first time: NOAA's Particle Analysis by Laser Mass Spectrometer (PALMS), University of California at Riverside's Aerosol Time-of-Flight Mass Spectrometer (ATOFMS), University of Delaware's Rapid Single-Particle Mass Spectrometer II (RSMS-II), and Aerodyne's Aerosol Mass Spectrometer (AMS). Although these mass spectrometers are generally classified as similar instruments, they clearly have different characteristics due to their unique designs. One primary difference is related to the volatilization/ionization method: PALMS, ATOFMS, and RSMS-II utilize laser desorption/ionization, whereas particles in the AMS instrument are volatilized by impaction onto a heated surface with the resulting components ionized by electron impact. Thus mass spectral data from the AMS are representative of the ensemble of particles sampled, and those from the laser-based instruments are representative of individual particles. In addition, the AMS instrument cannot analyze refractory material such as soot, sodium chloride, and crustal elements, and some sulfate or water-rich particles may not always be analyzed with every laser-based instrument. A main difference among the laser-based mass spectrometers is that the RSMS-II instrument can obtain size-resolved single particle composition information for particles with aerodynamic diameters as small as 15 nm. The minimum sizes analyzed by ATOFMS and PALMS are 0.2 and about 0.35 μm, respectively, in aerodynamic diameter. Furthermore, PALMS, ATOFMS, and RSMS-II use different laser ionization conditions. Despite these differences the laser-based instruments found similar individual particle classifications, and their relative fractions among comparable sized particles from Atlanta were broadly consistent. Finally, the AMS measurements of the nitrate/sulfate mole ratio were highly correlated with composite measurements (r2 = 0.93). In contrast, the PALMS nitrate/sulfate ion ratios were only moderately correlated (r2 ∼ 0.7).

Published 10 April 2003.

Index Terms: 0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 4801); 0345 Atmospheric Composition and Structure: Pollution—urban and regional (0305); 0394 Atmospheric Composition and Structure: Instruments and techniques.


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Citation: Middlebrook, A. M., et al. (2003), A comparison of particle mass spectrometers during the 1999 Atlanta Supersite Project, J. Geophys. Res., 108(D7), 8424, doi:10.1029/2001JD000660.