METHOD OF PREPARING CALIBRATION CURVE FOR ISOTOPE MEASUREMENT AND ISOTOPE MEASURING INSTRUMENT

摘要

PROBLEM TO BE SOLVED: To provide a method of preparing calibration curve which enables the measured value of the carbon dioxide concentration in a sample to be corrected without measuring the oxygen concentration in the sample, and to provide an isotope measuring instrument that can accurately measure the carbon dioxide concentration in the sample in a short time by simplifying the measuring procedure and maintenance by omitting an oxygen analyzer.;SOLUTION: In the method of preparing calibration curve for isotope measurement, two kinds of carbon dioxides ¹²CO₂ and ¹³CO₂ are measured by using a mixed gas containing the carbon dioxides ¹²CO₂ and ¹³CO₂ at various isotopic ratios in accordance with various concentration ratios and O₂ at a concentration decided from the relation between the CO₂ concentration and O₂ concentration of RQ=0.82 shown in Fig. 1 (a) as a calibrating gas and a calibration curve is prepared by correcting the influence of the O₂ concentration by interpolating the measured points. At the same time, the calibration curve and a data processing means using the curve are provided in a signal processing circuit 21 shown in Fig. 1 (b). Consequently, the measured value of the CO₂ concentration in the exhaled air of a subject can be found without measuring O₂ concentration in the air by means of an oxygen analyzer.;COPYRIGHT: (C)2003,JPO