Patent ID: 6455852
Filing Date: 2002-09-24
Classification: G01N

Abstract:
A stable isotope measurement method for spectrometrically analyzing an isotopic gas, which comprises the steps of introducing a test gas sample containing carbon dioxide 12CO2 and carbon dioxide 13CO2 as component gases into a cell, determining absorbances of light transmitted therethrough at wavelengths suitable for the respective component gases, determining concentrations of the respective component gases in the test gas sample on the basis of calibration curves prepared through measurement on gas samples each containing the component gases in known concentrations, whereintwo test gas samples are sampled from a single subject and, if a CO2 concentration of one of the test gas samples is higher than a CO2 concentration of the other test gas sample, the one test gas sample is diluted with air to a CO2 concentration level equivalent to that of the other test gas sample for measurement of the concentration ratios 13CO2/12CO2 in the respective test gas samples.