Abstract: The invention relates to an appliance for the oxidation of components in organic samples, in particular for the oxidation of components emerging from a gas chromatograph and for preparation for an analysis of isotope ratios by mass spectrometry, having a chamber with a gas inlet and a gas outlet, having an oxidizer inside the chamber and, in particular, having a heating appliance for the chamber. It is known to use copper oxide as oxidizer. The latter requires continual reoxidation to achieve sufficiently good results of measurement. In addition, at high temperatures, coagulation of the copper occurs. An oxidizer composed of nickel oxide is provided according to the present invention. This is extremely stable to temperature. The chamber receiving the oxidizer is advantageously lined with Al.sub.2 O.sub.3.

Abstract: Background of the invention is the isotope ratio analysis of carbon and nitrogen as components of hydrocarbon compounds. The separation into individual components takes place in a gas chromatograph and oxydation in a downstream combustion oven, into, inter alia CO.sub.2 and N.sub.2. In general CO.sub.2 is present in a much larger quantity than N.sub.2. The measurement values on the mass spectrometer have accordingly different dimensions. In order to approximate the peak values, a dilution with additional helium as a carrier gas takes place in the analysis of CO.sub.2. This has the additional advantage that the helium as a carrier gas, which is present anyway, as a result is present in approximately equal quantities relative to the CO.sub.2 and N.sub.2 in the ion source of the mass spectrometer. The dilution takes place in the region of a so-called open split (18).