Analysis of inorganic fiber concentrations in biological samples by scanning electron microscopy

Abstract

Analyzing fibers with electron microscopic techniques involves several preparation steps, especially during the analysis of fibers in human tissue. The influence of these steps on the analytical result was studied in detail. Fiber number was unaffected by the mild sonication of fiber suspensions analyzed with scanning electron microscopy. Significant fiber losses appeared during the filtration of fiber suspensions through 0.8-μm pore-size Nucleopore membranes. Shrinkage of the tissue during dry ashing broke long fibers and consequently increased the fiber concentration and affected the fiber length distribution. Dry ashing, however, removed more of the organic debris than wet ashing; thus specimens prepared with dry ashing were more suitable for scanning electron microscopic analysis. A fairly good correlation was demonstrated for the analysis of fibers with scanning and transmission electron microscopy.