Development of an Aerosol Mass Spectrometer for Size and Composition Analysis of Submicron Particles

The importance of atmospheric aerosols in regulating the Earth's climate and their potential detrimental impact on air quality and human health has stimulated the need for instrumentation which can provide real-time analysis of size resolved aerosol, mass, and chemical composition. We describe here an aerosol mass spectrometer (AMS) which has been developed in response to these aerosol sampling needs and present results which demonstrate quantitative mea surement capability for a laboratory-generated pure component NH4 NO3 aerosol. The instrument combines standard vacuum and mass spectrometric technologies with recently developed aerosol sampling techniques. A unique aerodynamic aerosol inlet (developed at the University of Minnesota) focuses particles into a narrow beam and efficiently transports them into vacuum where aerodynamic particle size is determined via a particle time-of-flight (TOF) measurement. Time-resolved particle mass detection is performed mass spectrometrically following particle flash vaporization on a resistively heated surface. Calibration data are presented for aerodynamic particle velocity and particle collection efficiency measurements. The capability to measure aerosol size and mass distributions is compared to simultaneous measurements using a differential mobility analyzer (DMA) and condensation particle counter (CPC). Quantitative size classification is demonstrated for pure component NH4 NO3 aerosols having mass concentrations 0.25mu g m -3. Results of fluid dynamics calculations illustrating the performance of the aerodynamic lens are also presented and compared to the measured performance. The utility of this AMS as both a laboratory and field portable instrument is discussed.

[1]  W. H. Walton.  The Mechanics of Aerosols , 1966 .

[2]  David Y. H. Pui,et al.  Equilibrium bipolar charge distribution of aerosols , 1974 .

[3]  K. T. Whitby,et al.  Aerosol classification by electric mobility: apparatus, theory, and applications , 1975 .

[4]  R. Gould,et al.  Mass spectrometric analyzer for individual aerosol particles , 1981 .

[5]  M. P. Sinha,et al.  Particle analysis by mass spectrometry , 1982 .

[6]  Anthony S. Wexler,et al.  On-line chemical analysis of aerosols by rapid single-particle mass spectrometry , 1995 .

[7]  P. Ziemann,et al.  Particle beam mass spectrometry of submicron particles charged to saturation in an electron beam , 1995 .

[8]  Peng Liu,et al.  Generating Particle Beams of Controlled Dimensions and Divergence: II. Experimental Evaluation of Particle Motion in Aerodynamic Lenses and Nozzle Expansions , 1995 .

[9]  David B. Kittelson,et al.  Generating Particle Beams of Controlled Dimensions and Divergence: I. Theory of Particle Motion in Aerodynamic Lenses and Nozzle Expansions , 1995 .

[10]  Daniel M. Murphy,et al.  Laser Ionization Mass Spectroscopy of Single Aerosol Particles , 1995 .

[11]  Bernhard Spengler,et al.  Simultaneous Detection of Positive and Negative Ions From Single Airborne Particles by Real-time Laser Mass Spectrometry , 1996 .

[12]  K. Prather,et al.  Aerodynamic Particle Sizing versus Light Scattering Intensity Measurement as Methods for Real-Time Particle Sizing Coupled with Time-of-Flight Mass Spectrometry. , 1996, Analytical chemistry.

[13]  K. Prather,et al.  Real-Time Measurement of Correlated Size and Composition Profiles of Individual Atmospheric Aerosol Particles , 1996 .

[14]  D. Murphy,et al.  Chemical composition of single aerosol particles at Idaho Hill: Positive ion measurements , 1997 .

[15]  K. Prather,et al.  On-Line Characterization of Individual Particles from Automobile Emissions , 1997 .

[16]  K. Prather,et al.  Real-time monitoring of pyrotechnically derived aerosol particles in the troposphere , 1997 .

[17]  K. Prather,et al.  Real‐time single particle monitoring of a relative increase in marine aerosol concentration during winter rainstorms , 1997 .

[18]  B. Morrical,et al.  Real-Time Analysis of Individual Atmospheric Aerosol Particles: Design and Performance of a Portable ATOFMS , 1997 .

[19]  P. Ziemann,et al.  Aerodynamic Lens System for Producing Particle Beams at Stratospheric Pressures , 1998 .

[20]  J. Seinfeld.  Clouds, contrails and climate , 1998, Nature.

[21]  Mahoney,et al.  In situ measurements of organics, meteoritic material, mercury, and other elements in aerosols at 5 to 19 kilometers , 1998, Science.

[22]  Tandem mass spectrometry of uranium and uranium oxides in airborne particulates. , 1998, Analytical chemistry.

[23]  L. D. Juan,et al.  Improvement of the Resolution of TSI's 3071 DMA via Redesigned Sheath Air and Aerosol Inlets , 1998 .

[24]  W. Whitten,et al.  Real-Time Characterization of the Organic Composition and Size of Individual Diesel Engine Smoke Particles , 1998 .

[25]  Dust in the wind. , 1998, Analytical chemistry.