Measurements by gas chromatography/pyrolysis/mass spectrometry:: fundamental conditions in 2H/1H isotope ratio analysis

Gas chromatography/pyrolysis/isotope ratio mass spectrometry (GC/P/IRMS) is a relatively new method for on-line determination of H-2/H-1 isotope ratios. The influence of different parameters on the H-2/H-1 isotope ratios obtained in GC/P/IRMS has been thoroughly studied using several flavor compounds, such as 5-nonanone, linalool, menthol, linalyl acetate and 4-decanolide. The requirement of 'conditioning' the pyrolysis reactor to obtain reliable delta(2)H(V-SMOW) values is discussed. Furthermore, the influence of the carrier gas flow of the gas chromatograph on the completeness of pyrolysis and subsequently on the delta(2)H(V-SMOW) values is investigated in detail. The linear range of the compounds investigated is determined. The results show that calibrating the GC/P/IRMS system with secondary standard substances is absolutely necessary in order to obtain reliable delta(2)H(V-SMOW) values. In view of interlaboratory comparability, validation procedures are recommended. Copyright (C) 2002 John Wiley Sons, Ltd.