岩石・鉱物中の18O/16O比の測定法-1-酸素ガスの同位体比測定用炭酸ガスへの変換法について

概要

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A method is described to obtain carbon dioxide from oxygen gas which is extracted by a fluorine decomposition technique from silicate and oxide minerals for the isotope analysis of oxygen. The method is a modification of that described by Taylor and Epstein. A small piece of spectrographic graphite is heated externally in a quartz tube and oxygen is carefully combusted to carbon dioxide, the latter being quickly condensed into a liq.-nitrogen trap near the heated graphite(Fig.1). The yield of carbon dioxide is nearly 100 per cent in the range of temperature examined(440 to 580°C)and the isotope analysis of oxygen can be performed with accuracy of less than 0.2 per mil(Table 2).<BR> It is also shown that the kinetic isotope effect of oxygen in the combustion process is as large as 2.2 per cent at 500°C (Table 3 and Fig. 2) . A preliminary discussion is made for the reaction mechanism of the process.
日本質量分析学会の論文