Published: Jan 1958
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Although it was developed primarily for the analysis of fissionable materials, the capillary trap method for oxygen in metals should have wide usefulness. As in vacuum fusion, the sample is fused in a graphite crucible with a flux, but a stream of argon at atmospheric pressure is used in place of high vacuum. Carbon monoxide is converted by Schütze's reagent to carbon dioxide, which is condensed in a capillary trap and measured with a capillary manometer. Most determinations require only 12 min. Platinum is preferred as a flux because it has a very low vapor pressure and dissolves only a moderate amount of carbon, avoiding the “solidification” which occurs with iron. Platinum is not an effective flux for the refractory metals such as tantalum and tungsten; platinum-cobalt and platinum-iron alloys dissolve these metals but give somewhat low results on known samples. The platinum bath gave a standard deviation of 7 ppm on 50-mg plutonium samples, and samples with added oxygen gave correct results within 2 per cent of the total oxygen. Twenty-two elements and numerous alloys have been analyzed. The method is especially recommended for rapid routine determinations.
Smiley, William G.
University of California, Los Alamos Scientific Laboratory, Los Alamos, N. M.