Sizing of Particulates for Environmental Health Studies

1978:128: Millette

Scanning Electron Microscopy I: 253-258

Abstract:

In studying the health effects of particulates ingested through drinking water it is important to have accurate methodologies for determining particle size distributions. While transmission electron microscope (TEM) analysis procedures have been developed to characterize fibrous particulates by morphology, electron diffraction, and x-ray energy dispersive analysis, measurement of fiber lengths by scanning electron microscopy (SEM) may be useful in some cases. A sample preparation technique for particle sizing purposes should provide a randomly distributed sample which allows for both scanning electron microscope (SEM) imaging of the particles directly on the filter and preparation of TEM grids.
Two methods, one using 0.1 ?m Nuclepore and the other using 0.1 ?m Millipore type filters, were studied closely by counting and sizing standard suspensions of short chrysotile fibers on TEM and SEM preparations. No difference was seen in the size distribution results of the two filter methods. Concentration values determined from SEM photomicrographs were very close to the values determined using TEM analysis. The fiber distributions on the filters were found to be random distributions as tested by the Chi-Square goodness of fit to the Poisson distribution.

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