Trapping charged nanoparticles in the nano aerosol mass spectrometer (NAMS)

Abstract Particle trapping in the nano aerosol mass spectrometer (NAMS) is investigated through a combination of modeling and experimental measurements to understand and optimize the trapping process. In the NAMS, charged nanoparticles pass through an aerodynamic lens, digital ion guide (DIG) and field adjusting lens (FAL) prior to entering a digital ion trap (DIT) where they are captured and subsequently analyzed. The DIT is operated with a square wave potential applied to the ring electrode. SIMION modeling was used to study particle motion from the exit aperture of the DIG into the DIT. Several parameters were characterized including particle starting position, kinetic energy, trajectory and FAL design. A new FAL assembly was designed to increase the number of trapped particles. The new design was found to increase the rate that ambient particles are analyzed by over an order of magnitude. With the new design, an ambient aerosol concentration (d N /dlog  d m ) of 1 × 10 3  cm −3 yields approximately 2–3 particles analyzed per minute.

[1]  Heewon Lee,et al.  Computer Simulation of the Operation of a Three-Dimensional Quadrupole Ion Trap , 1992 .

[2]  Da-Ren Chen,et al.  A High Efficiency, High Throughput Unipolar Aerosol Charger for Nanoparticles , 1999 .

[3]  P. Mcmurry,et al.  Aerodynamic Focusing of Nanoparticles: I. Guidelines for Designing Aerodynamic Lenses for Nanoparticles , 2005 .

[4]  S. Dobashi,et al.  On-line monitoring method of PCBs by laser ionization dynamic trapping time of flight mass spectrometry , 2004 .

[5]  M. Johnston,et al.  New particle formation and growth in the troposphere. , 2010, Analytical chemistry.

[6]  Lung-Chi Chen,et al.  In Vitro Assessment of the Inflammatory Response of Respiratory Endothelial Cells Exposed to Particulate Matter , 2010, Journal of toxicology and environmental health. Part A.

[7]  M. Johnston,et al.  Airborne nanoparticle characterization with a digital ion trap–reflectron time of flight mass spectrometer , 2006 .

[8]  S. Liu,et al.  NH4+, NO3−, and SO42− in roadside and rural size-resolved particles and transformation of NO2/SO2 to nanoparticle-bound NO3−/SO42− , 2009 .

[9]  T. Xia,et al.  Toxic Potential of Materials at the Nanolevel , 2006, Science.

[10]  Ashok Gidwani,et al.  Aerodynamic Focusing of Nanoparticles: II. Numerical Simulation of Particle Motion Through Aerodynamic Lenses , 2005 .

[11]  M. Johnston,et al.  Nanoparticle Chemical Composition During New Particle Formation , 2011 .

[12]  M. Johnston,et al.  Chemical characterization of individual, airborne sub-10-nm particles and molecules. , 2006, Analytical chemistry.

[13]  B. Brunekreef,et al.  Relationship between different size classes of particulate matter and meteorology in three European cities. , 2005, Journal of environmental monitoring : JEM.

[14]  Jorge Boczkowski,et al.  What's new in nanotoxicology? Implications for public health from a brief review of the 2008 literature , 2010, Nanotoxicology.

[15]  L. Ding,et al.  A simulation study of the digital ion trap mass spectrometer , 2002 .

[16]  J. Smith,et al.  A Thermal Desorption Chemical Ionization Ion Trap Mass Spectrometer for the Chemical Characterization of Ultrafine Aerosol Particles , 2009 .

[17]  B. Vijay Bhaskar,et al.  Atmospheric Particulate Pollutants and their Relationship with Meteorology in Ahmedabad , 2010 .

[18]  T. Masujima,et al.  Computer simulation of the gap-tripole ion trap with linear injection, 3D ion accumulation, and versatile packet ejection , 2008, Journal of the American Society for Mass Spectrometry.

[19]  M. Johnston,et al.  Time-resolved chemical composition of individual nanoparticles in urban air. , 2008, Environmental science & technology.

[20]  R. March.  An Introduction to Quadrupole Ion Trap Mass Spectrometry , 1997 .

[21]  S. Beu,et al.  SIMION modeling of ion image charge detection in Fourier transform ion cyclotron resonance mass spectrometry , 2009 .

[22]  M. Johnston,et al.  Apportionment of motor vehicle emissions from fast changes in number concentration and chemical composition of ultrafine particles near a roadway intersection. , 2011, Environmental science & technology.