赤外分光光度計およびガスクロマトグラフによる液体酸素中の不純物分析法
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概要
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Heretofore the quantitative analysis for small amounts of impurities of liquid oxygen has been carried out mostly as follows: acetylene by the Ilosvay reagent method, and hydrocarbons by the combustion method. In the latter case, the result of analysis can only be expressed as total carbon value, and in order to know the amount of each hydrocarbon separately it has been necessary to resort to some other methods, for example the mass-spectrography. The present writers have used an infrared spectrophotometer and a gas chromatograph in combination for this purpose. The liquid oxygen sample was taken into a 100m<I>l</I> Erlenmeyer flask and evaporated at a rate of 8<I>l</I> per minute into a brass trap at liquid oxygen temperature in order to condense the impurities.<BR>The collected impurities were gas-chromato graphed into fractions and accepted in separate glass traps, thereafter being introduced into infrared cells for the identification by mercury replacement.<BR>Another method they tried was to put liquid oxygen sample in a pressure vessel and after complete vaporization make an analysis using a 10m infrared cell.<BR>The results obtained were: (1) Quantitative analysis by the gas chromatograph could be performed to the minimum detectable quantities of 3.5×10<SUP>-4</SUP> ppm carbon dioxide, 7×10<SUP>-4</SUP> ppm nitrous oxide and 1.3×10<SUP>-3</SUP>2×10<SUP>-4</SUP>ppm hydrocarbons up to C<SUB>4</SUB>, and (2) by the infrared method using 10m cell they were able to detect as little as 2ppm methane, 0.1ppm nitrous oxide, 4ppm carbon dioxide, 1ppm hydrocarbons up to C<SUB>3</SUB>, 0.4ppm ethylene, 0.01ppm acetylene, 0.01ppb carbon tetrachloride, 0. 01ppb ethylene trichloride and 10ppb sulfur dioxide.
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