HIGH-PRECISION ISOTOPIC DETERMINATION OF THE O-18 O-16 AND O-17/O-16 RATIOS IN NITROUS-OXIDE/

A decomposition system has been developed for the quantitative convers ion of nitrous oxide to molecular nitrogen and oxygen for high-precisi on mass spectrometric isotopic determinations. N2O is thermally decomp osed (>800 degrees C) to N-2 and O-2 in the presence of a gold catalyt ic surface. N-2 and O-2 are quantitatively separated using previously developed techniques. This system is unique in that it allows measurem ent of both the O-18/O-16 and O-17/O-16 ratios in N2O. Data are presen ted for samples of commercially obtained N2O with its corresponding ox ygen isotopic composition and decomposition yields.