Absolute measurements of isotope amount ratios on gases: Part II. Application of the measurement models developed on real gases

The power of the theoretical formalisms based on concepts from kinetic gas theory described in Part I of this series, is demonstrated in isotope measurement results obtained for three different gases: CO2, SiF4 gas highly enriched in the 28Si isotope and a high purity neon gas of natural isotopic composition. The measurement procedure as described in this paper enables to detect various (small) anomalies in the gas mass spectrometer during the ion current measurements thus creating the opportunity to correct for them.Using these concepts which govern the isotope fractionation of the gas in the mass spectrometer and performing a calibration by means of synthesized values for isotope amount ratios, SI traceable values in terms of the derived measurement unit mol/mol can be obtained.