A comparison of calculation procedures for isotope dilution determinations using gas chromatography mass spectrometry

Several data reduction procedures have been used for converting isotope ratios, determined using gas chromatography mass spectrometry, into mole ratios for the purpose of quantitating organic compounds. In this report, these procedures are shown to be related under certain limiting approximations of original sample and internal standard isotope ratios. With the understanding that some of the procedures involve approximations, the incorporation of related systematic errors into calculated mole ratio values was investigated. The results indicate that certain data reduction procedures allow quantitation over wider mole ratio ranges and with internal standards which contain a significant quantity of unlabeled impurity.