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

Abstract

Better techniques are needed to analyze airborne fiber material in the lungs of workers. Analyzing fibers with EM 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-.mu.m pore-size nuclepore membranes. Shrinkage of the tissue during dry ashing broke long fibers and increased fiber concentration and affected fiber length distribution. Dry ashing removed more organic debris than wet ashing; 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.