Time-of-flight aerosol

RW Niven. Aerodynamic particle size testing using a time-of-flight aerosol beam spectrometer. Pharm Technol 17 72-78, 1993. 

Time-of-flight aerosol beam spectrometry was first described by Dahneke in 1973 [139]. A commercial instrument, the Aerosizer, [140] was developed by Amherst Process Instruments Inc. which is now a division of Thermo Systems Inc.The TSI Model 3603 replaces the Aerosizer. 

Figure 4.7 Schematic of the time-of-flight aerosol mass spectrometer (TOF-AMS). Aerosol is introduced into the instrument through an aerodynamic lens focusing the particles through a skimmer and an orifice onto the vaporizer. Particle vapor is ionized and the ions are guided into the TOF-MS, which generates mass spectra at 83.3 kHz repetition rate. For particle size measurement the particle beam is chopped with a mechanical chopper and the detection is synchronized with the chopper opening time [178], Aerosol Science Technology A New Time-of-Flight Aerosol Mass Spectrometer (TOF-AMS) - Instrument Description and First Field Deployment. 39 637-658. Copyright 2005. Reston, VA. Reprinted with permission...

Drewnick F, Kings SS, DeCarlo PF, Jayne JT, Gonin M, Fuhrer K, Weimer S, Jimenez JL, Demeqian KL, Borrmann S, Worsnop DR. A new Time-of-Flight Aerosol Mass Spectrometer (ToF-AMS)-instrument description and first field deployment. Aerosol Sci Technol. 

DeCarlo PF, Kimmel JR, Trimborn A, Northway MJ, Jayne JT, Aiken AC, Gonin M, Fuhrer K, Horvath T, Docherty KS, Worsnop DR, Jimenez JL. Field-deployable, high-resolution, time-of-flight aerosol mass spectrometer. Anal Chem. 2006 78 8281-9. 

Several sophisticated centrifugal instruments for concurrent sampling and sizing of aerosols were developed in the period from 1950 to 1980 [42—46]. These tend to have been displaced by laser diffraction studies (see Chapter 7) and time-of-flight aerosol... 

R. W. Niven, Aerodynamic Particle Size Testing Using the Time of Flight Aerosol Beam Spectrometer , Pharm. TechnoL, 17 (1993) 72—78. 

The AeroSizer, manufactured by Amherst Process Instmments Inc. (Hadley, Massachusetts), is equipped with a special device called the AeroDisperser for ensuring efficient dispersal of the powders to be inspected. The disperser and the measurement instmment are shown schematically in Figure 13. The aerosol particles to be characterized are sucked into the inspection zone which operates at a partial vacuum. As the air leaves the nozzle at near sonic velocities, the particles in the stream are accelerated across an inspection zone where they cross two laser beams. The time of flight between the two laser beams is used to deduce the size of the particles. The instmment is caUbrated with latex particles of known size. A stream of clean air confines the aerosol stream to the measurement zone. This technique is known as hydrodynamic focusing. A computer correlation estabUshes which peak in the second laser inspection matches the initiation of action from the first laser beam. The equipment can measure particles at a rate of 10,000/s. The output from the AeroSizer can either be displayed as a number count or a volume percentage count. 

Methods for analysis of the particle size distribution in the aerosol cloud include techniques such as time of flight measurement (TOE), inertial impaction and laser diffraction. Dynamic light scattering (photon correlation spectroscopy) is confined to particles (in suspension) in the submicron range. In addition to the size distribution, the particle velocity distribution can be measured with the Phase Doppler technique. 

Bentz, J. W. G J. Goschnick, J. Schuricht, H. J. Ache, J. Zehnpfen-nig, and A. Benninghoven, Analysis and Classification of Individual Outdoor Aerosol Particles with SIMS Time-of-Flight Mass Spectrometry, Fresenius J. Anal. Chem., 353, 603-608 (1995b). 

Marijnissen, J., B. Scarlett, and P. Verheijen, Proposed On-Line Aerosol Analysis Combining Size Determination, Laser-Induced Fragmentation, and Time-of-Flight Mass Spectroscopy, ./. Aerosol Sci., 19, 1307-1310(1988). 

Nordmeyer, T., and K. A. Prather, Real-Time Measurement Capabilities Using Aerosol Time-of-Flight Mass Spectrometry, Anal. Chem., 66, 3540-3542 (1994). 

Vogt, L., Groger, T. and Zimmermann, R. (2007) Automated compound classification for ambient aerosol sample separations using comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry. Journal of Chromatography A, 1150, 2 12. 

Murray, K.K., Lewis, T.M., Beeson, M.D. and Russell, D.Fl. (1994) Aerosol matrix-assisted laser desorption ionization for liquid chromatography/time-of-flight mass spectrometry. Anal. Chem. 66, 1601-1609. 

Figure A. 11 Schematic diagram of the system components for particEe analysis by mass spectrometry, (a) Interface with external aerosol. Panicles ate introduced from the exterior through an aerosol beam with associated skimmers into (b) volatilizing and Ionizing region. The arrival of each panicle at the detector location is sensed by a laser that energizes a more powerful laser which focuses on the incoming particle to generate tons that pass to the (c) mass spectrometer, which may be of various types including quadrupole or time-of-flight. (From Sinha el al. 1983.)...

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