抄録
A gas chromatographic method for separating CO2 and N2O was developed to measure 13C/12C ratios of atmospheric CO2. The mixture of N2O and CO2, which was condensed out from an air sample, was separated by passing through a column packed with porous silica beads, and only CO2 was recovered for δ13C measurements. It was confirmed that the gas chromatographic separation of CO2 does not change the δ13C value of CO2. Urban air samples in Tokyo and oceanic air samples in the northwestern Pacific were analyzed by using this method. The δ13C value of separated CO2 was shown to be 0.20 ± 0.03‰ greater than the value obtained when the CO2-N2O mixture was directly introduced to the mass spectrometer.
