Aerosol particle size analysis

Particle size determines more or less the origin, the chemical and optical properties, the mechanism of removal from the atmosphere and therefore it plays an important role in the sampling strategy planning. Generally particles with diameter less than 2.5 p-m are referred to as fine, and those with greater diameter are referred to as eoarse (aerosol particle size analysis is described in Griffits et al. (1998)). 

Griffits, W., Mark, D., Marshall, I., Nichols, A., 1998. Aerosol Particle Size Analysis. Royal Society of Chemistry, Cambridge, UK, pp. 116. 

Pfafflin, J. R. and E. N. Ziegler, eds. 2006. Encyclopedia of Environmental Science and Engineering, 5th ed. Boca Raton, EL CRC Press. This work is written for the practitioner and those with a science background. After brief definitions or introductions, each chapter quickly focuses on technical details. Eor example, the chapter on aerosols includes a table of physical interpretation for characteristic diameters of various particles, provides defining equations, and methods of aerosol particle size analysis. 

D. Sinclair, A New Photometer for Aerosol Particle Size Analysis ,/. Air Pollution Control Assoc., 7 (2) (February 1967) 105—108. 

Aharonson, E. F., Karasikov, N., Roitberg, M., Shamir, J., Galai-CIS-l-A Novel Approach to Aerosol Particle Size Analysis, J. Aerosol Sci., 1986, 17, 530-536. 

The preceding sections have focused on the properties of distributions in general without considering any particular type of distribution. In this section, we describe the characteristics and applications of the lognormal distribution for aerosol particle size analysis. As discussed below, the normal distribution, although widely used elsewhere, is not suitable for most aerosol particle size distributions. 

For determination of the aerodynamic diameters of particles, the most commonly apphcable methods for particle-size analysis are those based on inertia aerosol centrifuges, cyclones, and inertial impactors (Lundgren et al.. Aerosol Measurement, University of Florida, Gainesville, 1979 and Liu, Fine Paiiicles—Aerosol Generation, Measurement, Sampling, and Analysis, Academic, New York, 1976). Impactors are the most commonly used. Nevertheless, impactor measurements are subject to numerous errors [Rao and Whitby, Am. Ind. Hyg. A.s.soc.]., 38, 174 (1977) Marple and WiUeke, "Inertial Impactors, in Lundgren et al.. Aerosol Measurement and Fuchs, "Aerosol Impactors, in Shaw, Fundamentals of Aerosol Sci-... 

Particle Size Analysis Many particle-size-analysis methods suitable for dry-dust measurement are unsuitable for liquids because of coalescence and drainage after collection. Measurement of particle sizes in the flowing aerosol stream by using a cascade impactor is one... 

During the development of the generating system, particle size analysis should be performed to establish the stability of aerosol concentrations. 

Hotham, G.A. Particle size analysis of aerosols in medicine. In Respiratory Aerosols Gale, A.E., Ed. Gordon Harris St. Agnes, South Australia, 1981 47-71. 

Laser Diffraction Methods Over the past 30 years laser diffraction has developed into a leading principle for particle-size analysis of all kinds of aerosols, suspensions, emulsions, and sprays in laboratory and process environments. 

Particle size analysis of pharmaceutical aerosols has a strong foundation based on other disciplines. Most of the analytical techniques used were in existence before the development of the modem pharmaceutical aerosol dosage form. However, some significant challenges have to be overcome in the use of these techniques for assessing pharmaceutical systems. 

Fnrthermore, for dosage consistency, there is a need for an aerosol formulation to be monodispersed [4]. The particle size distribution of an aerosol is defined by its geometric standard deviation (GSD). The GSD is the ratio of particle diameters at 84% and 50% cnmnlative mass of particles or the ratio of the particle diameters at 50% and 16% cnmnlative mass of particles when the cumulative mass of particles is plotted against the eqnivalent diameter on a log-probability scale following particle size analysis nsing either impactors or laser diffraction instruments. 

Mitchell JP, Nagel MW, Wiersema KJ, et al. Aerodynamic particle size analysis of aerosols from pressurized metered-dose inhalers comparison of Andersen 8-stage cascade impactor, next generation pharmaceutical impactor, and model 3321 aerodynamic particle sizer aerosol spectrometer. AAPS PharmSciTech 2003 4 E54. 

Allen, T., Particle Size Measurement (Powder Technology Series), 5th edn, Chapman Hall (November 1997), ISBN 0 41275 350 2 Bernhardt, 1. C., Particle Size Analysis—Classification and Sedimentation Methods, Chapman Hall (September 1994), ISBN 0 41255 880 7 Gy, P. and Royle, A. G. (translator). Sampling for Analytical Purposes, John Wiley Sons Ltd (abridged 153 pages) (July 1998), ISBN 0 47197 956 2 Kaye, B. H., Characterization of Powders and Aerosols, John Wiley Sons Ltd (January 1999), ISBN 3 52728 853 8... 

Raabe, O. G., Particle Size Analysis Utilizing Grouped Data and the Log-Normal Distribution, J. Aerosol Sci., 2, 289-303 (1971). 

Chan TL, D Arcy JB, Schreck RM. High-solid paint overspray aerosols in a spray painting booth particle size analysis and scrubber efficiency. Am Ind Hyg Assoc J 1986 47 411-417. 

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. 

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