Senior scientistMember of ASTM, Union Carbide Corp., Metals Division, Niagara Falls, N.Y.
This paper presents the results of an evaluation of high-magnification microscopic techniques used to analyze fiber contamination in water conducted by an ASTM Task Group under Subcommittee E04.11 on Electron Metallography. These techniques offer a feasible means of measuring relatively low levels of fiber contamination in environmental water samples. Other bulk-type methods lack the needed sensitivity and selectivity. The transmission electron microscope is the best basic instrument for the analysis, particularly when it is equipped with selected area electron diffraction and energy-dispersive spectroscopy capabilities. The mean fiber concentrations by different groups agree within a factor of two. The interlaboratory reproducibility of 50% can be expected in relatively clean water samples unless the concentration is low. In samples with high concentrations of interfering solids, the precision will not be as good. Interlaboratory reproducibility of 25% is as good as the method can provide. When applied on a broad scale there are variable and significant losses associated with the condensation washing of samples containing amphibole. The losses are low and less varible when condensation washing is used to prepare samples containing chrysotile.
Paper ID: JTE10949J