A combination of gas chromatography, combustion, and C-13/C-12 isotope dilution mass spectrometry (GC/C/IDMS)

A new method is presented for amount-of-substance measurements in organic chemistry using isotope dilution mass spectrometry in combination with gas chromatography. Its main feature is the conversion of analyte and spike, after the chromatographic separation, into carbon dioxide which is subjected to the isotope ratio measurement. This modification is used because the techniques of n(C-13)/n(C-12) ratio measurements in CO2 are very well developed so that high accuracy in results is achieved. As carbon dioxide is used for the isotope ratio measurement, it is necessary to use C-13-labelled organic compounds as spikes. From the results of a model analysis it is reasonable to expect that the new GC/C/IDMS method is capable of providing measurement results with a higher accuracy than has been possible up to now.