Patent ID: 6078049
Filing Date: 2000-06-20
Classification: G01N

Abstract:
A method for concentration calibration of a stable isotope analyzer employed for isotope proportion measurements in a measurement gas, wherein the measurement gas is a component of a gas mixture which consists of the measurement gas and an additional gas, the additional gas being devoid of the measurement gas and the gas mixture, the method including:preparing the gas mixture by mixing the measuring gas and the additional gas, which gas mixture has a relatively high measurement gas concentration and known isotope proportions;determining a first point on a calibration curve of isotope proportions versus concentration measurement values, the determining of the point including:determining a first concentration of the measurement gas in the gas mixture, andmeasuring a first isotope proportion in the gas mixture;determining another point on the calibration curve by:reducing the concentration of the measurement gas in the gas mixture by supplying a gas devoid of the measurement gas and the gas mixture,determining another concentration of the measurement gas in the gas mixture, andmeasuring another isotope proportion in the gas mixture;repeating the steps of reducing the concentration of the measurement gas in the gas mixture, determining another concentration of the measurement gas, and measuring another isotope proportion a plurality of times to produce a calibration curve.