A Mass spectrometric method for identification of N2O emission sources.

Abstract

A thermogravimeteric-gas chromatographic/mass spectrometric system (TG-GC/MS) which was coupled by a concentration interface, was developed for the identification of the emission sources based on a ratio of 14N15NO to 14N14NO signals. Such fossil fuels as coals were burnt in a thermogravimeter (TG) under the flow of a mixture gas of O2 and Ar. The evolved N2O gas was trapped in an adsorbing tube which was cooled in a dry ice bath. The adsorbed N2O gas was desorbed by heating the trapping tube, and delivered to the GC/MS system. N2O gas (MW=44) was chromatographically separated from CO2 (MW=44) and its isotopic peaks were mass spectrometrically detected at m/z=44 (14N14NO) and 45 (14N15NO). This ratio was measured for the exhaust gas from combustion of several kinds of coal, the atmospheric air and a synthesized N2O gas. The difference in the ratios among those gases suggests the possibility to discriminate the N2O emission sources.